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J^arbarli College i-ttirarg
LIBRARY OF THE
DEPARTMENT OF EDUCATION
BUREAU OF VOCATIONAL GUIDANCE
TRANSFERRED
EGE
NEW YORK
THE NORMAM W. HENLEY PUBLISHING COMPANY
S WEST 45th STREET
1919
Z-r^. bxi.^r.^
^^
--r--^"f^-t5tr
NARVARD UNIVERSITY
DIVISION OF EDUCA (ION
WWtlAU or VOCATIONAL UU1»AN0&
r"
HARVARD COLLEGE LIBRARY
IRANSFEI^ED FROM THE
LIBRARY OF THE
eUADUATE SCHOOL OF EDUCATK)!!
1930
B
n
Copyrighted 1917 and 1916, by THE NORMAN W. HENLEY PUBLISHING COMPANY
All Rights Reserved
SIXTH IMPRESSION
NOTE. — AU iUustrations in this book have been specially made by the publishers, and their use without permission is strictly prohibited.
6 ' Introduction
One of the pronounced developments of the last six years has been the general adoption of various starting means for setting the engine in motion without recourse to the usual form of hand crank. Some of these motor starting systems merely re- place the usual hand crank with some means of turning the motor over without leaving the seat by purely mechanical connections. Very few, on 1912 and 1913 models of obsolete cars, depend on air pressure, while the most popular and generally applied forms to 1919 model cars depend on electricity as a source of power for a small electric starting motor. Electric starting and lighting sys- tems have been made in many forms, though the basic principles of operation are practically the same in all systems that can be grouped in several main classifications. It will not be possible to describe all in a general treatise of this nature, but if the features of the leading systems are outlined it will not be difl5cult for the repairman or student to become familiar with the principle of other systems which may be slightly different only in points of minor detail. Not only are the various parts of leading systems shown, but as a result of the co-operation of the leading automobile manufacturers, the author is enabled to show the actual applica- tion of the various ignition, generating and starting units to lead- ing power plants. While a certain amount of technical exposition is unavoidable, everything has been stated as simply as possible so readers without technical knowledge can understand the prin- ciples and method of operation, as well as location of troubles in the popular systems. The illustrations have been carefully selected and all wiring diagrams are of representative systems actually in use. The reader not versed in electrical science will find that care- ful perusal of the chapter on "Elementary Electricity and Mag- netism" will enable him to understand many of the more technical descriptions and wiring diagrams. As electricity is used for oper- ating many accessory devices besides the lighting, ignition and motor starting units, a chapter is devoted to the unusual applica- tions of the electric current.
The Author.
May, 1919.
8 Contents
PAcas Cylinder Ignition — Coils for Multiple Cylinder Ignition — ^Arrange- ment of Coil Terminals — ^High Tension Coil Ignition System — ^Timer and Distributor Forms — ^Timers for One Cylinder — ^Multiple Contact Timers — ^Roller Contact Timer — ^Arrangement of Timer Contacts — Ball Contact Timer — Atwater-Kent Timer — Secondary Distributors — ^Delco Ignition System — ^Delco Timer — ^Delco Automatic Timer Advance — Delco Ignition Coil — ^Kesistance Unit — ^Delco Condenser — Delco Circuit Breaker — ^Ammeter — Combination Switch — 1916 Delco Ignition Distributor — Timing Delco Ignition — ^Westinghouse Igni- tion Unit — Spark Plug Forms — Spark Plug Design — Construction of Spark Plugs — Spark Plug Insulation — Spark Plug Installation — Plugs for Two-Spark Ignition — Individual Coil Ignition System — Typical Battery Ignition Systems — ^Vibrator Coil — ^Distributor Sys- tems— ^Ford Magneto and Coil Ignition System — ^Master Vibrator System — Non- Vibrator Coil Distributor System — Closed Circuit Systems — Connecticut Automatic Ignition — Thermostatic Switch Belease — ^Low Tension System — Low Tension Igniter Plate- Double Ignition Systems — ^Triple Ignition Systems — ^Battery Ignition System Troubles — ^Testing Dry Cells — ^Dry Cell Defects — C!are in Dry Cell Installation — Storage Battery Faults — Charging Storage Bat- teries— Appliances for Storage Battery Maintenance — ^Remedies for Loss of Battery Capacity — "Flushing'' Undesirable — Cure for Sul- phated Plates — ^Battery Charging Apparatus — ^Rectifiers for Alter- nating Current — ^Lamp Bank Resistance for Direct Current — ^Edison Cell Features — ^Winter Care of Storage Batteries — ^Freezing Points of Electrolyte — Spark Plug Faults — Testing Spark Plugs — ^Repairing Spark Plugs — Setting Plug Gaps — ^Induction Coil Troubles and Remedies — Adjusting Coil Vibrators — ^Roller Contact Timer Troubles — ^Wiring Troubles — Electro-static Effects — "Bucking," Cause and Remedy — ^Battery Ignition System Hints — Timing Battery Ignition Systems 66 to 184
CHAPTER III
MAGNETO IGNITION SYSTEMS
Magneto Generator Construction — Single Cylinder Magneto — Multiple Cylinder Magneto — Magneto Systems — Arrangement of Distributor Contacts — Speed of Armature Rotation — Low Tension Magneto Systems — Simple Low Tension Magnetos — Oscillating Armature Type — Governed Rotating Armature Type — ^Inductor Magnetos —
10 Contents
PAcns Third Brush Begolation — TTpical Deleo Systems — Dyneto-Entz One- Unit System — Advantages of One-Unit — Installation of Dyneto— Non-Stalling Feature — Current Output of Dyneto— Cfhalmers-Entz System — ^Auto-Lite Two-Unit System — ^Auto-Lite-Overland Systems — 1914 Gray & Davis System — Functions of Parts — ^Path of Current — Current Begulation — ^Typical Gray & Davis Systems — ^1915 Gray & Davis System — ^Automatic Cut Out and Current Regulator — One* Unit Ford System — Genemotor-Ford System — ^Northeast Ldghting and Starting System — ^Dodge-Northeast System — ^Northeast-Univer- sal System — ^Bijur Starting and Lighting Systems — ^Bijur-Scripps Booth One-Unit — ^Bijur Two-Unit System — ^Bijur Output Begulating Means — ^Vibrator Type Regulator — ^Typical Bijur Systems — Simms- Huff Single Unit System — Charging Scheme in Huff System — ^How Unit is Connected to Engine — ^Tracing Simms-Huff Circuits — ^Bosch- Rushmore System — ^De-Luxe System — Standard System — ^Bosch- Rushmore System Parts — ^Remy Starting, Lighting and Ignition Systems — ^Remy System Units — ^Remy Current Regulation — ^Remy Two- Armature System — Westinghouse Systems — Kemco-Fan Genera- tor System — ^Hartford Starting and Lighting System — ^U. S. L.- Jeffery System 312 to 421
CHAPTER VI
STARTING SYSTEM FAULTS AND THEIR SYSTEMATIC
LOCATION
Locating Troubles in Gray & Davis System — Ammeter Indications a Guide — Systematic Search for Faults — ^Locating Short Circuit — Faults in Motors and Generators — ^Refitting Brushes — Care of Com- mutator— ^Faults in Wiring — Short Circuits — Open Circuits — ^Protec- tion of Wiring — Care of Lamps — ^Brief Instructions for Care of Bat- . tery — ^Hints for Locating Delco Troubles — Delco Testing Volt- Am- meter— ^Delco Test Points — ^Indications of Delco Generator Troubles — ^Testing for Defective Windings — Grounded Generator Coil — Shorted Generator CoU — Open Generator CoU — Grounded Motor Winding — ^Testing Cut-out Relay — ^Voltage Regulator Troubles — Voltmeter Test — ^Troubles in Dyneto System — Dyneto Will Not Start — Lamps Burn Dimly — ^Dyneto Starts Slowly — ^Dyneto Does Not Gen- erate— ^Bosch-Rushmore Troubles — Adjusting Automatic Relay — Adjusting Regulator — ^Remy System Troubles — Starter Will not Turn Engine — Grounds and Short Circuits — All Lights Go Dim — Generator Test — Starting Motor — Instructions for Repairing Storage Battery 422 to 466
Contents
11
CHAPTER VII
MISCELLANEOUS ELECTEICAL DEVICES
PAGES
Glaring Headlights — ^Methods of Reducing Glare — ^Dimming Headlights — ^Light Deflectors — ^Light Filters — ^Electrical Alarms — ^Buzzer Horns — ^Motor-Driven Horns — ^Direction Indicators — Electrical Bear Sig- nals— ^Vulcan Electric Gearshift — How Electric Gearshift Operates — Function of Solenoids — Selective and Master Switch — ^Hartford Electric Brake — Electric Air Heater — ^Automatic Circuit Breaker or Safety Switch — ^Lighting Gas Headlights by Electricity — ^Low Volt- age Electric iVulcanizers — Simple Rectifier — ^Entz Electric Trans- mission— Operating Principles — Practical Application — ^Typical Lighting System — Novel Electrical Lamps — New Bulb Forms — ^Dry Battery Lamps — ^Wagner Two-Unit System — Electrical Equipment of 1917 Cars ' . . 467 to 510
INDEX 611 to 519
READY REFERENCE TO ALL WIRING
DIAGRAMS
PAGB
Atwater-Kent XJnisparker System 84
Anto-Lite-ChevTolet System ^ 345
Auto-Lite Two-Unit System 34I
Battery Ignition System (Elementary) 75
1915 Bijur-Packard System (Insert B) between 302-303
Bijnr-Apperson Two-Unit System 372
Bijur-Hnpmobile System 380
Bijur-Packard Twin Six System 378
Bijur-Scripps Booth System 371
Bijur Voltage Regulation Circuits 373
Bijur-Winton Six System 382
Bosch Dual Ignition System 219
Bosch High Tension Magneto (Simplified) 190
Bosch-Honold Magnetic Plug System 223
Bosch-Marmon System De-Luxe 393
Bosch-Bushmore Type A Motor 397
Bosch-Standard System {Insert) between 388-389
Circuits of Bemy-Oakland 32 System 399
Chalmers-Entz System 340
Complete Lighting System 490
Connecticut Closed Circuit System 121
Connecticut Thermostat Wiring 123
Delco-Buick System 324
Delco-Cadlllac 1912 System 437
Delco-Cadillac 1913 System 439
1914 Delco-Cadillac System 313
1914 Delco-Olds System (Insert A ) between 302-303
1916 Delco-Cadillac System 333
Delco-Cole 1915 Eight Cylinder System 441
Delco Combination Switch Circuits 98
1916 Delco-Hudson System (Non-Technical) 330
1916 Delco-Hudson System (Technical) 331
Delco Ignition System, Elementary 93
Delco-Oakland System (Non-Technical) 434
Beady Reference to all Wiring Diagrams
PAGE
Bemy-lTational Two-Annature System 402
Bemy-Beo System {Insert) between 402-403
Bemy Two Spark Magneto 222
Bemy Type B. L. Magneto System 215
Simms-Duplez Ignition System 217
Simms-HufF-Mazwell System 387
Simms-Hnff System (Simplified) 384
Simple Battery Ignition System 68
Six Cylinder Battery-Coil-Distribntor System 116
Six Cylinder Triple System 131
Splitdorf Transformer-Coil System 213
Technical Diagram, Gray & Davis Two-Unit 351
Technical Diagram, Gray & Davis Two-Wire System 354
Testing Delco Armature Windings 449
Transformer Coil-Magneto System 192
Two Spark Magneto Ignition 221
XT. S. Xfc-Jeffery System 420
TJnisparker System 84
Use of Lamp Bank Besistance 154
Vulcan Electric Gearshift Circuits 478
WestinghQUse Ignition Generator Circuits 407
Westinghouse Ignition Unit System 101
Westinghouse Lighting System 410
Westinghouse-Pierce-Arrow System 411
Westinghouse Starting Motor Circuits 408
Wiring Qf Lamp and Test Points 445
ADDED TO 1917 EDITION
Circuits 499
Wacpier-Studebaker Circuits 500
18 Starting, Lighting and Ignition Systems
it is capable of doing work. The passage of electricity through any piece of apparatus is termed a current. If the flowing of the electrical charges is continuous it is called a direct current. If the charges are not continuous but flow always in the same direction it is termed a ** pulsating'' current. If an electrical charge flowing in one direction is followed by another charge flowing in the op- posite direction, an ** alternating" current is produced.
It will be evident that to obtain a regular flow a constant supply of electricity, such as afforded by some electrical generator is required. The simplest analogy to permit the reader to under- stand the passage of a current is the flow of a stream of water. A number of comparisons can be made between water and the electric current which tend to simplify the explanation, though it is understood that there can be little in common between such a tangible fluid as water is and electricity which is intangible and only considered a fluid for convenience. To form some conception of this force, it is well to consider that we are able to place various bodies in different electrical relations. A stick of sealing wax or a hard rubber comb, rubbed on a coat sleeve, will attract bits of paper, feathers and other light objects. The sealing wax or rubber is said to be charged with electricity which has been produced by friction against the coat sleeve. Any body charged with electricity may be considered one whose surface is supplied with either an over- charge or undercharge of electricity. The overcharged body al- ways tends to discharge to the undercharged body in order to equalize a difference in pressure existing between them. An elec- trical machine capable of producing current may distribute this current as desired, providing the current is sufficiently strong to overcome the resistance to its motion of the parts comprising the external circuit.
Why Current Flows. — The action of an electrical machine in regulating the distribution of electricity may be considered to be the same as that of a pump which takes water from one tank and supplies it to another at a higher level. If for these reservoirs we consider bodies insulated from each other, we can, with an electri- cal generator take electricity from one that has been overcharged and supply it to another which is undercharged. If we had two
20
Starting^ Lighting and Ignition Systems
emptied quicker but the water would have a greater head or pres- sure. The same condition exists on electrified bodies as the ^eater the diflference of potential or level between them the more rapid the flow and the greater the pressure of the current.
The levels of liquids in the tanks instead of being compared to each other might be referred to that of an ocean of constant level. Water might be pumped into the ocean from one or from the ocean to one or both so as to affect the level of water in the tanks with respect to the larger quantity in the ocean of constant height. Electricity can be considered in the same manner. It can be taken
Tank ni ted
Tank Empty
J^d
B
J Wire
Eleetrio Motor
Wire
Pipe
Dry Ceil
Fig. 1. — ^Diagrams Illustrating How Current Pressure Causes Electricity to Flow by Comparing It to a Flow of Water ftom One Tank to Another.
from an ocean of electricity, which may be represented by the electrical charge present at all points of the earth or the earth can be used, as it invariably is, as a receptacle for the charges obtained from electrical producers.
In Fig. 1 is shown two tanks, A and B, connected by a pipe. Let tank A, which is filled with water, represent the positive ele- ment K of the cell P, and the empty tank B the negative element L. Let pipe E connecting the two tanks represent wires J con- necting the two elements: It is evident that water will flow through the pipe from the full tank to the empty tank until both contain the same quantity and the pressures are equal. Likewise in the battery cell electricity will flow through the wire from the positive
22 Starting J Lighting and Ignition Systems
trical conductors, steel or iron is next in order, while some alloys, such as German silver, offer considerable resistance to the flow oi current.
Materials such as wood, glass, rubber, etc., and air, conduct electricity so badly as to be termed insulators. What would nor- mally be an insulator to a current of low potential may be rup- tured by a current of higher potential or pressure which can break down the resistance. From the foregoing it will be evident that a current is produced by the passage of electricity from one body to another and that current can only flow through certain ma- terials and that some substances act as a barrier to the current flow just as a valve stops the flow of water. With a valve in thp water pipe, providing that the parts were sufficiently strong, clos- ing the valve breaks the continuity of the pipe and stops the flow of water. The same is true of electricity, it must have a complete circuit or the currents cannot pass. An electrical circuit is said to be an open circuit when the current cannot flow and a closed circuit, if there is a continuous path for the electricity.
A closed circuit therefore is one made up entirely of apparatus and wires capable of conducting electricity, including some form of generator of electrical energy which acts as a pump to produce a flow. The flow of current is from the electrical generator, through wires to the piece of apparatus to be operated and from that piece of apparatus back again to its source. If we connect the terminals of the battery through the wire to the bell, after energizing the bell magnets the electricity does work by ringing the bell. It flows from the positive or carbon terminal of the battery through the wire to the bell and after energizing the bell magnets, it returns through another conductor to the zinc or negative terminal of the battery. Inside of the cells, the flow is from the negative member to the positive member. Any closed circuit may be made an open circuit by including an insulating body which resists current flow. This body is always of such a form that it can be temporarily bridged over by a conductor when it is desired that the current pass through the circuit. All electrical circuits must comprise a source of current, wires to carry it, a switch to interrupt it and apparatus to be actuated by it.
i
How Current is Produced
23
Current Production by Chemical Action. — The simplest method of current generation is by various forms of chemical current pro- ducers which may be either primary or secondary in character. A simple form of cell is shown in section at Fig. 3, A, and as the action of all devices of this character is based on the same principles it will be well to consider the method of producing electricity by the chemical action of a fluid upon a metal. The simple cell shown
Pressure Gauge
@
^
Valve
The Drop In Pressure between Pump and Motor Is due to Valve being only opened a small Amount,
Pressure Gauge
0
Rheostat
110 Volts
The Drop in Pressure between Generator and Motor is due to the Resistance of Rheostat being cut in.
Volts
B
Fig. 2. — ^Diagrams Outlining How* Current Voltage is Reduced by In- creasing Besistance in Circuit. A — Water Flow Reduced by Shut-off Valve. B — ^Electric Flow Reduced by Rheostat^ an Equivalent of tbe Valve in tbe Water System.
consists of a container which is filled with an electrolyte which may be either an alkali or acid solution. Immersed in the liquid are two plates of metal, one being of copper, the other zinc. A vire is attached to each plate by means of suitable screw terminals. tf the ends of the plates which are not immersed in the solution are joined together a chemical action will take place between the electrolyte and the zinc plate ; in fact, any form of cell consists of dissimilar elements which are capable of conducting electricity im-
24
Starting, lAghting and Ignition Systems
mersed in a liquid which will act on one of them more than the other. The chemical action of electrolyte on the zinc liberates gas bubbles which are charged with electricity and which deposit them- selves on the copper plate. The copper element serves merely as a collecting member and is termed the ' ' positive ' ' plate, while the zinc which is acted upon by the solution is termed the "negative" -mem- ber. The flow of current is from the zinc to the copper plate through
Fig. 3. — simple Frlmar? Cell Used to Produce Electric Cuirsnt. A — Form to Show Principle of Current Production by Chemical Actton. B — Dry Cell, the Type Suitable for AaUmoblle Service.
the electrolyte and it is returned from the copper plate to the zinc element by the wiring which comprises the external circuit.
While in the cell shown zinc and copper are used, any other com- bination of metals between which there exists a difference in elec- trical condition when one of them is acted upon by a salt or acid may be employed. Any salt or acid solution will act as an elec- trolyte if it will combine chemically with^one of the elements and if it does not at the same time offer too great a resistance to the passage of the electric current. The current strength will vary with the nature of the elements used, and will have a higher value
Action of Chemical Current Producer 25
when the chemical action is more pronounced between the negative member and the electrolyte.
As the vibrations which obtain when the automobile is driven over highways makes it. difficult to use cells in which there is a surplus of liquid, a form of cell has been devised in which the liquid electrolyte is replaced by a solid substance which cannot splash out of the container even if the cell is not carefully sealed. A current producer of this nature is depicted in sjpction at Fig. 3, B. This is known as a dry cell and consists of a zinc can in the center of which a carbon rod is placed. The electrolyte is held close to the zinc or negative member by an absorbent lining of blotting paper, and the carbon rod is surrounded by some de- polarizing material. The top of the cell is sealed with pitch to prevent loss of depolarizer.
' The depolarizer is needed that the cell may continue to generate current. When the circuit of a simple cell is completed the current generation is brisker than after the cell has been producing elec- tricity for a time. While the cell has been in action the positive element becomes covered with bubbles of hydrogen gas, which is a poor conductor of electricity and tends to decrease the current output of the cell. To prevent these bubbles from interfering with current generation some means must be provided for disposing of the gas. In dry cells the hydrogen gas that causes polarization is combined with oxygen gas evolved by the depolarizing medium and the combination of these two gases produces water which does not interfere with the action of the cell. Carbon is used in a dry cell instead of copper because it is a cheaper material and the electrolyte is a mixture of salammoniac and chloride of zinc which is held in intimate contact with the zinc shell which forms the negative element by the blotting paper lining.
Wiring Dry Cells. — When dry cells are used for ignition there are two practical methods of connecting these up. At least four dry cells are necessary to secure satisfactory ignition and much more energetic explosions will be obtained if five or six are used. The common method is to join the cells together in series as shown at Pig. 4, A. When connecting in this manner the carbon terminal of one battery is always coupled to the zinc binding post of its
26 Starting, Lighting and Ignition Systems
Cavers chafed -Zinc sheila In contact ^oose TermPiala
Terminals In contact
Frayed wire
Fig. 4. — ^Methods of Connecting Dry Cells and Precautions to be Observed
When Wiring.
neighbor. Connection would be made from the carbon of the first cell to the zinc of the second, from the carbon of the second to the zinc of the third, and from the carbon of the third to the zinc of the fourth, this leaving the zinc terminal on the first cell and the carbon terminal on the fourth cell free to be joined to the external circuit. When dry cells are connected in series the
Wiring Dry Cell Battery 27
voltage is augmented, that of one cell being multiplied by the number so joined. The amperage remains the same as that of one cell. If a dry cell has a potential ot 1%. volts, a battery com- posed of four cells would show 5 volts. When dry batteries are used for lighting purposes or for igniting multiple cylinder en- gines, in order to obtain better results, they are connected in series multiple, as shown at B. Three sets of cells joined in series are placed side by side with the free carbons at one end in line and the zincs at the other also in line. The three carbons are then joined together by one wire, the three zinc terminals by an- other. "When joined in this manner the battery has a voltage equal to that of four cells and an amperage equal to that of three cells. If a series connected battery as at A indicated 5 volts and 20 amperes, the series multiple connection at B will indicate 5 volts and 60 amperes. When cells are joined in multiple the drain on any one cell is reduced and it is not so likely to become ex- hausted as when four are used in series. The points to be watched out for when installing dry batteries are clearly outlined at the bottom of Fig. 4. It will be seen that it is not desirable for termi- nals to come in contact with each other or with the sides of the box or is it conducive to good ignition to have the zinc shells in contact. A loose terminal on any one of the batteries will re- sult in irregular ignition while a broken wire will interrupt it altogether. If the insulation is frayed where a wire passes through a hole in a metal battery box trouble may be experienced due to short circuiting of the current between the bare wire and the steel box, which may be grounded.
One of the disadvantages of primary cells, as those types which utilize zinc as a negative element are called, is that the chemical action produces deterioration and waste of material by oxidization. Dry cells are usually proportioned so that the electrolyte and de- polarizing materials become weaker as the zinc is used and when a dry cell is exhausted it is not profitable to attempt to recharge it because new ones can be obtained at a lower cost than the expense of renewing the worn elements would be.
The number of dry cells necessary will vary with the system of ignition employed and the size of the motor. While two or three
28 Starting, Lighting and Ignition Systems
cells will ignite small engines such as used in motorcycles, five or six will be needed on automobile engines employing high-tension ignition. When the make-and-break system, or low-tension method, is used eight or ten cells are necessary. If the engine is a multiple cylinder one, it will draw more current than a single cylinder type because of the greater frequency of sparks. On four-cylinder cars dry cells should be joined in multiple series, which is the most economical arrangement. Cells used in multiple connection are more enduring than if the same number were used independently in single-series connection. A disadvantage of a dry cell battery is that it is suited only for intermittent service and it will soon be- come exhausted if used where the current demands are severe. For this reason most automobiles in which batteries are used for igni- tion employ storage or secondary batteries to furnish the current regularly used and a set of dry cells is provided for use only in cases of emergency when the storage battery becomes exhausted.
Principles of Storage Battery Construction. — Some voltaic couples are reversible, i. e., they may be recharged when they have become exhausted by passing a current of electricity through them in a direction opposite to that in which the current flows on dis- charge.' Such batteries are known as '* accumulators" or ''storage batteries." A storage battery belies its name as it does not store current and its action is somewhat similar to that of the simpler chemical cell previously described. In its simplest form a storage cell would consist of two elements and an electrolyte, as outlined at Fig. 5, A. The storage battery differs from the primary cell in that the elements are composed of the same metal before charg- ing takes place, usually lead instead of being zinc or carbon. One of the plates is termed the ''positive" and may be distinguished from the other because it is brown, or chocolate in color after charging, while the negative plate is usually a light gray of leaden color. The active material of a charged storage battery is not metallic lead but oxides of that material.
The simple form shown at A consists of two plates of lead which are rolled together separated by insulating bands of rubber at the top and bottom to keep them from touching. This roll is immersed in an electrolyte composed of a weak solution of sul-
Principles of Storage Battery Action 29
phurie acid in water. Before such a cell can be used it must be charged, which consists of passing a current of electricity throagh it until the lead plates have changed their nature. After the charging process is complete the lead plates have become so changed in nature that they may be considered as different sub- stances and a chemical action results between the negative plate and the electrolyte and produces current just as in the simple cell
Fig. 5. — Types of Accunmlatora or Stor&ge Batteries. A — Simple Form of Oell. B — ^Battery Composed of Tliree Cells Sucb as ComraoDl; Used for Ignition Purposes,
shown at Pig. 3, A, When the ceU is exhausted the plates return to their metallic condition and are practically the same, and as there is but little difference in electrical condition existing be- tween them, they do not deliver any current until electricity has been passed through the cell so as to change the lead plates to oxides of lead instead of metallic lead.
When storage cells are to be used in automobile work they are combined in a single containing member, as shown at Fig. 5, B,
30 Starting, Lighting and Ignition Systems
which is a part sectional view of a Geiszler storage battery. The main containing member, a jar of hard rubber, is divided into three parts. Each of these compartments serves to hold the ele- ments comprising one cell. The positive and negative plates are spaced apart by wood and hard rubber separators which prevent short circuiting between the plates. After the elements have been put in place in the compartments forming the individual cells of the battery, the top of the jar is sealed by pouring a compound of pitch and rosin, or asphaltum, over plates of hard rubber, which keeps the sealing material from running into the cells and on the plates. Vents are provided over each cell through which gases produced by charging or discharging are allowed to escape. These are ^o formed that while free passage of gas is provided for, it is not possible for the electrolyte to splash out when the vehicle is in motion.
It will be evident that this method of sealing would not be practical on a cell where the members attacked by the acid had to be replaced from time to time, but in a storage battery only the electrolyte need be renewed. When the plates are discharged they are regenerated by passing a current of electricity through them. New electrolyte or distilled water can be easily inserted through holes in which the vents are screwed. The cells of which a storage battery is composed are joined together at the factory with bars of lead which are burned in place and only two free terminals are provided by which the battery is coupled to the outer circuit.
The capacity of a storage battery depends upon the size and the number of plates per cell, while the potential or voltage is determined by the number of cells joined in series to form the battery. Each cell has a difference of potential of two and two tenths volts when fully charged, therefore a two-cell battery will deliver a current of four and four tenths volts and a three-cell type, as shown in part section at Fig. 6, will give about six and six tenths volts between the terminals. In the form shown each cell is composed of a number of plates and their separators. One group of the plates is positive, the remaining negative members. The size of storage battery to be used depends upon the number qt cylinders of the engine and also if battery is to be used for
Storage Battefy Construction 31
startiog and lighting purposes as well as ignition. Four-eylinder motors usually take s six-volt, sixty-ampere-hour battery, but it is desirable to supply a six-volt battery having eighty-ampere-hour capacity for six-cylinder motors for ignition only. For lighting or starting 100 ampere hour batteries are needed.
When chemical current producers are depended upon to supply the electricity used for ignition, two distinct sets are provided,
EiiimnsloD Chamber to take care of Chansea la Volnma of S^utlon durlDB Chusa
Fig. & — Special Storage Battery Desl^d to Funilsli Ugbtlngj and Starting Cnirent,
one for regular service and the other for emergency use in event of failure of that which is depended upon regularly. The com- mon practice is to provide an accumulator or storage battery for normal use and a set of dry cells, which are cheaper in first cost and which do not deteriorate if not used for some time, for emer- gency service. When two sources of current are thus provided, a switch is included in the circuit so that either set may be used at will. The zinc terminal of the dry battery and the negative terminal of the storage battery are joined together by a suitable
82 Starting, Lighting and Ignition Systems
conductor and are grounded by running the wire attached to them to some metal part of the chassis such as the crank case or frame side member. The remaining terminals, which are the positive of the storage battery and the carbon of the dry cell, are coupled to distinct terminals on the switch block.
The fact that any battery cannot maintain a constant supply of electricity has militated against their use to a certain extent knd the modern motorist demands some form of mechanical gener- ator driven from the power plant, which will deliver an unfailing supply of electricity and keep the battery charged. The strength of batteries is reduced according to the amount of service they give. The more they are used the weaker they become. The modern multiple cylinder engines are especially severe in their requirements upon the current producer and the rapid sequence of explosions in the average six- or eight-cylinder motor produce practically a steady drain upon the battery. "When dry cells are used their discharge rate is very low and as they are designed only for intermittent work, when the conditions are such that a constant flow of current is required, they are unsuitable and will soon deteriorate. A more comprehensive discussion on the care, repair and charging of storage batteries will be found in the following chapter.
Fundamentals of Magnetism Outlined. — To properly under- stand the phenomena • and forces involved in the generation of electrical energy by mechanical means it is necessary to become familiar with some of the elementary principles of magnetism and its relation to electricity. The following matter can be read with profit by those who are not familiar with the subject. Most persons know that magnetism exists in certain substances, but many are not able to grasp the terms used in describing the operation of various electrical devices because of not possessing a knowledge of the basic facts upon which the action of such apparatus is based.
Magnetism is a property possessed by certain substances and is manifested by the ability to attract and repel otter materials sus- ceptible to its effects. When this phenomena is manifested by a conductor or wire through which a current of electricity is flowing it is termed ''electro-magnetism.'' Magnetism and electricity are
Fundamentals of Magnetism 88
closely related, each being capable of producing the other. Prac- tically all of the phenomena manifested by materials which possess magnetic qualities naturally can be easily reproduced by passing a current of electricity through a body which, when not under elec- trical influence, is not a magnetic substance. Only certain sub- stances show magnetic properties, these being iron, nickel, cobalt and their alloys.
The earliest known substance possessing magnetic properties was a stone first found in Asia Minor. It was called the lodestone or leading stone, because of its tendency, if arranged so it could 1)6 moved freely, of pointing one particular portion toward the north. The compass of the ancient Chinese mariners was a piece of this material, now known to be iron ore, suspended by a light thread or floated on a cork in some liquid so one end would point toward the north magnetic pole of the earth. The reason that this stone was magnetic was hard to define for a time, until it was learned that the earth was one huge magnet and that the iron ore, being particularly susceptible, absorbed and retained some of this magnetism.
Most of us are familiar with some of the properties of the mag- net because of the extensive sale and use of small horseshoe mag- nets as toys. As they only cost a few pennies everyone has owned one at some time or other and has experimented with various ma- terials to see if they would be attracted. Small pieces of iron or steel were quickly attracted to the magnet and adhered to the pole pieces when brought within the zone of magnetic influence. It was soon learned that brass, copper, tin or zinc were not affected by the magnet. A simple experiment that serves to illustrate magnetic attraction of several substances is shown at A, Fig. 7. In this, several balls are hung from a standard or support, one of these being of iron or steel, the other two of any other of the common materials or metals. If a magnet is brought close to the group of balls, only one will be attracted toward it, while the others will remain indifferent to the magnetic force. Experimenters soon learned that of the common metals only iron or steel were magnetic.
If the ordinary bar or horseshoe magnet be carefully examined, one end will be found to be marked N. This indicates the north
34 Starting, Lighting and Ignition Systems
Inn Attracted by UagiM,
Formt of Magnets.
I
Attractim Brtaeen llaBitta,
ritlda of Magnetic Inflmnea.
Hannliat Magnst,
Tig, 7. — Stoiia Simple Ezperlmenta to Demonstrate Tarions magnetic Pbenomena and to Oleul? OutUne Effect* of Magnotism and romu of Magnets.
36 Starting^ Lighting and Ignition Systems
The form of magnet used will materially affect the size and area of the magnetic field. It will be noted that the field will be con- centrated to a greater extent with the horseshoe form because of the proximity of the poles. It should be understood that these lines have no actual existence, but are imaginary and assumed to exist only to show the way the magnetic field is distributed. The magnetic influence is always greater at the poles than at the center, and that is why a horseshoe or U-form magnet is used in practi- cally all magnetos or dynamos. This greater attraction at the poles can be clearly demonstrated by sprinkling iron filings on bar and U magnets, as outlined at E, Fig. 7. A large mass gathers at the pole pieces, gradually tapering down toward the point where the attraction is least.
From the diagrams it will be seen that the flow of magnetism is from one pole to the other by means of curved paths between them. This circuit is completed by the magnetism flowing from one pole to the other through the magnet, and as this flow is continued as long as the body remains magnetic it constitutes a magnetic cir- cuit. If this flow were temporarily interrupted by means of a conductor of electricity moving through the field there would be a current of electricity induced in the conductor every time it cut the lines of force. There are three kinds of magnetic circuits. A non-magnetic circuit is one in which the magnetic influence com- pletes its circuit through some substance not susceptible to the force. A closed magnetic circuit is one in which the influence completes its circuit through some magnetic material which bridges the gap between the poles. A compound circuit is that in which the magnetic influence passes through magnetic substances and non-magnetic substances in order to complete its circuit.
How Iron and Steel Bars are Made Magnetic. — Magnetism may be produced in two ways, by contact or induction. If a piece of steel is rubbed on a magnet it will be found a magnet when removed, having a north and south pole and all of the properties found in the energizing magnet. This is magnetizing by contact. A piece of steel will retain the magnetism imparted to it for a considerable length of time, and the influence that remains is known as residual magnetism. This property may be increased by
Electricity and Magnetism Related 37
alloying the steel with tungsten and hardening it before it is mag- netized. Any material that will retain its magnetic influence after removal from the source of magnetism is known as a permanent magnet. If a piece of iron or steel is brought into the magnetic field of a powerful magnet it becomes a magnet without actual contact with the energizer. This is magnetizing by magnetic in- duction. If a powerful electric current flows through an insulated conductor wound around a piece of iron or steel it wall make a magnet of it. This is magnetizing by electro-magnetic induction. A magnet made in this manner is termed an electro-magnet and usually the metal is of such a nature that it will not retain its magnetism when the current ceases to flow around it. Steel is used in all cases where permanent magnets are required, while soft iron is employed in all cases where an intermittent magnetic action is desired. Magneto field magnets are always made of steel alloy, so treated that it will retain its magnetism for lengthy periods.
Electricity and Magnetism Closely Related. — There are many points in which magnetism and electricity are alike. For instance, air is a medium that offers considerable resistance to the passage of both magnetic influence and electric energy, although it offers more resistance to the passage of the latter. Minerals like iron or steel are very easily influenced by magnetism and easily penetrated by it. When one of these is present in the magnetic circuit the magnetism will flow through the metal. Any metal is a good con- ductor for 'the passage of the electric current, but few metals are good conductors of magnetic energy. A body of the proper metal will become a magnet due to induction if placed in the magnetic field, having a south pole where the lines of force enter it and a north pole where they pass out.
"We have seen that a magnet is constantly surrounded by a mag- netic field and that an electrical conductor when carrying a cur- rent is also surrounded by a field of magnetic influence. Now if the conductor carrying a current of electricity will induce mag- netism in a bar of iron or steel, by a reversal of this process, a magnetized iron or steel bar will produce a current of electricity in a conductor. It is upon this principle that the modem dynamo or magneto is constructed. If an electro-motive force is induced
88 Starting, Lighting and Ignition Systems
in a conductor by moving it across a field of magnetic influence, or by passing a magnetic field near a conductor, electricity is said to be generated by magneto-electric induction. All mechanical generators of the electric current using permanent steel magnets to produce a field of magnetic influence are of this type.
Basic Principles of Magneto Action Outlined. — The accom- panying diagram, Fig. 8, will show these principles very clearly. As stated earlier in this chapter, if the lines of force in the magnetic field are cut by a suitable conductor an electrical impulse ^11 be produced in that conductor. In this simple machine the lines of force exist between the poles of a horseshoe magnet. The con- ductor, which in this case is a loop of copper wire, is mounted upon a spindle in order that it may be rotated in the magnetic field to cut the lines of magnetic influence present between the pole pieces. Both of the ends of this loop are connected, one with the insulated drum shown upon the shaft, the other to the shaft. Two metal brushes are employed to collect the current and cause it to flow through the external circuit. It can be seen that when the shaft is turned in the direction of the arrow the loop will cut through the lines of magnetic influence and a current will be generated therein.
The pressure of the current and the amount produced vary in accordance to the rapidity with which the lines of magnetic in- fluence are cut. The armature of a practical magneto, therefore, differs materially with that shown in the diagram. A -large num- ber of loops of wire would be mounted upon this shaft in order that the lines of magnetic influence would be cut a greater numbei of times in a given period and a core of iron used as a backing f oi the wire. This would give a more rapid alternating current and a higher electro-motive force than would.be the case with a smallei number of loops of wire.
The illustrations at Fig. 9 show a conventional double wind ing armature and field magnets of a practical magneto in part sec tion and will serve to more fully emphasize the points previously made. If the armature or spindle were removed from between th( pole pieces there would exist a field of magnetic influence as showi at Fig. 7, but the introduction of this component provides a con
Magneto Action
89
duetor (the iron core) for the magnetic energy, regardless of its position, though the facility with which the influence will be trans- mitted depends entirely upon the position of the core. As shown at
Field Magnet
Mb Pieces
iM)
Insulated Ring Loop of Wire Spindle
Brushes
J
Pig. 8. — Elementary Form of Magneto Having Principal Farts Simplified to Make Method of Current Generation Clearer.
A, th« magnetic flow is through the main body in a straight line, while at B, which position the armature has attained after one- eighth revolution, or 45 degrees travel in the direction of the arrow, the magnetism must pass through in the manner indicated. At C, which position is attained every half revolution, the magnetic
40 Starting^ Lighting and Ignition Systems
energy abandons the longer path through the body of the core for the shorter passage offered by the side pieces, and the field thrown out by the cross bar disappears. On further rotation of the arma- ture, as at D, the body of the core again becomes energized as the magnetic influence resumes its flow through it. These changes in the strength of the magnetic field when distorted by the armature core, as well as the intensity of the energy existing in the field, affect the windings and the electrical energy induced therein corre- sponds in strength to the rapidity with which these changes in mag- netic flow occur. The most pronounced changes in the strength of the field will occur as the armature passes from position B. to D, because the magnetic field existing around the core will be de- stroyed and again reestablished.
During the most of the armature rotation the changes in strength will be slight and the currents induced in the wire corre- spondingly small ; but at the instant the core becomes remagnetized, as the armature leaves position C, the current produced will be at its maximum, and it is necessary to so time the rotation of the armature th9,t at this instant one of the cylinders is in condition to be fired. It is imperative that the armature be driven in such relation to the crankshaft that each production of maximum cur- rent coincides with the ignition point, this condition existing twice during each revolution of the armature, or at every 180 degrees travel. Each position shown corresponds to 45 degrees travel of the armature, or one-eighth of a turn, and it takes just one-half revolution to change the position from A to that shown at D. (See Fig. 10 also.)
Essential Parts of a Magneto and their Functions. — The mag- nets which produce the influence that in turn induces the electrical energy in the winding or loops of wire on the armature, and which may have any even number of opposed poles, are called field mag- nets. The loops of wire which are mounted upon a suitable drum and rotate in the field of magnetic influence in order to cut the lines of force is called an armature winding, while the core is the metal portion. The entire assembly is called the armature. The exposed ends of the magnets are called pole pieces and the arrange- ment used to collect the current is either a commutator or a col-
Magneto Action
pig. 9. — Showing How Strengtli of Magnetic Influence and of ttie Oui- Tent Induced in tlie Windings of Magneto Aimatuie Vary with the Bapldlty of Changes of Direction In Flow.
Starting, Lighting and Ignition Systems
46 Starting, Lighting ana Igmtion Systems
of many turns of finer wire. The arrangement of these windings can be readily ascertained by reference to the diagram B, Fig, 12, which shows the principle of operation very clearly. One end of the primary winding (coarse wire) is coupled or grounded to the armature core, and the other passes to the insulated part of the interrupter. While in some forms the interrupter or contact breaker mechanism does not revolve, the desired motion being im- parted to the contact lever to separate the points by a revolving
Tig. 12. — DiBgTamH Explaining Action of Low Tension or TranBloinier OoU Magneto Syatera at A and Trne High Tension Magneto System at B.
earn, in this the cam or tripping mechanism is stationary and the contact breaker revolves. This arrangement makes it possible to ■conduct the current from the revolving primary coil to the inter-
48 Starting, Lighting and Ignition Systems
exist. When the current reaches its maximum value, because of the armature being in the best position, the cam operates the in- terrupter and the points are separated, breaking the short circuit which has existed in the primary winding.
The secondary circuit has been open while the distributor arm has moved from one contact to another and there has been no flow of energy through this winding. While the electrical pressure will rise in this, even if the distributor arm contacted with one of the segments, there would be no spark at the plug until the contact points separated, because the current in the secondary winding would not be of sufficient strength. When the interrupter oper- ates, however, the maximum primary current will be diverted from its short circuit and can flow to the ground only through the sec- ondary winding and spark-plug circuit. The high pressure now existing in the secondary winding will be greatly increased by the sudden flow of primary current, and energy of high enough poten- tial to successfully bridge the gap at the plug is thereby produced in the winding.
Dynamo Electric Machines. — Two distinct types of mechanical generators are in common use, and while their principles of action are practically the same, they differ somewhat in construction and application. The forms first used to succeed the battery were modifications of the larger dynamo electric machines used for de- livering current for power and lighting. Later developments re- sulted in the simplification of the dynamo, by which it was made lighter and more efficient, and the modern magneto igniter is the form usually furnished on conventional power plants. A dynamo uses electro-magnets to produce a magnetic field for the armature to revolve in, and is necessarily somewhat heavier and larger than a magneto of equal capacity because the field in the latter instru- ment is produced by permanent magnets. An important advantage in using the magneto form of construction is that the weight of the windings is saved because the permanent magnets retain their magnetism and do not require the continual energizing that an electro-magnet demands.
The dynamo construction is superior where a continual drain is made upon the apparatus, because if a magneto is used continu-
60 Starting, Lighting and Ignition Systems
of simple design is shown at Fig. 14. All parts are clearly indicated and there should be no difficulty in understanding the principles of operation. The three main portions of the ds^iamo are the field magnets, which produce the magnetic field, the arma- ture, which carries the coils of wire and which is mounted between the extremities or pole pieces of the magnet, and the brushes, which bear against segments of a collecting device known as a commu- tator serving to convey the current to terminals which are joined to the outer circuit. In the form shown the field magnets are
Flfr U. — Oiajr & Davis Ooveraed Dynamo, an Appliance for Piodndng Electricity bjr Uechanical Means.
composed of a number of iron stampings which are surrounded by a coil of wire, and two such magnets are provided, one above, the other below, the armature. The armature is supported on a shaft mounted in ball bearings so that it will turn with minimum friction. The whole mechanism is protected by an outer casing.
The device shown is a constant speed dynamo, i.e., it should be operated at a certain speed to obtain the best results. If run faster than the speed for which it is designed the excess current gener- ated is liable to burn out the windings of the field magnet. For this reason a governor of the fly ball type is interposed between th©
Dynamo Generator Action 51
dynamo armature and the driving shaft coupled to the source <rf power. At all normal speeds the tension of the governor spring Iceeps the two plates of the clutch in contact and the armature is turned at the same speed as the driving shaft.
Should the driving shaft speed exceed a certain predetermS.rWj limit the governor weights will fly out by centrifugal force and the
Fig. Ifi. — How Oray b Davis Oenerator is Driven by Silent Oliain Oon- nection witli Guglne Cranksbaft.
governor spring will be compressed so the driving and driven plates of the clutch are separated and the driving shaft revolves inde- pendently of the armature. As soon as the armature speed becomes reduced sufficiently to allow the governor spring to overcome the centrifugal force and draw back the governor weights, the clutch
52 Starting, Lighting and Igmtion Systems
plates are again brought into contact and the armature is again jolaed to the driving shaft.
A current of air is kept circulating through the casing by means of the fan action of the reenforcing webs of the clutch plate, the ifcjeet being to absorb any heat which may be produced while
Tig. IS. — Diatliictive Toim of Oonent Fiodncei Used on Ford Oars is Incorporated in the Power Plant FlywliMl.
the dynamo is in action. An appliance of this nature may be driven from the engine by belt, chain, or gear connection (Pig. 15) . It will deliver low voltage current which must be transformed by means of an inducetion coil to current of higher value in order that it may be successfully utilized to produce the spark in the combustion chambers of the engine.
Flywheel Magneto Construction 53
A very ingenious application of the dynamo is shown at Figs. 16 and 17. The electrie generator is built in such a manner that it forms an integral part of the power plant. The magneto field is produced by a series of revolving magnets which are joined to and turn with the fly wheel of the motor. The armature coils are carried by a fixed plate which is attached to the engine base. This apparatus is really a magneto having a revolving field and a fixed armature, and as the magnets are driven from the fiy wheel there is no driving connection to get out of order and cause trouble.
r^g. 17. — The Ford Magneto Is Integxal wlUt Engine Bue and Revolving Magnets are Attaclied to Flywlieel Permitting Dliect Drive from CTankaliaf t without Oears.
Aa the coils in which the current is generated are stationary, no commutator or brushes are needed to collect the current because the electricity may be easily taken from the fixed eoila by direct connection. It has been advanced that this form of magneto is not as efficient as the conventional patterns, because more metal and wire are needed to produce the current required. As the magnets which form the heavier portion of the apparatus are joined to the fly wheel, which can be correspondingly lighter, this disadvantage is not one that can be considered seriously because the magnet weight is added to that of the motor fly wheel, the
54 Starting, Lighting and Ignition Systems
combined weight of the two being that of an ordinary balance member used on any other engine of equal power.
Methods of Winding Djmajnos. — The reader not versed in elec- trical science is apt to be puzzled by the designation of the various windings used on dynamos and motors. The armature windings and field coils may be connected together in a number of ways, as outlined at Pig. 18. The simple machine shown at A uses a per- manent magnet to produce the field and therefore has only one set of windings to be considered/ i. e., those on the armature. When the field magnet is an electro magnet another set of windings must be considered, i. e., those of the field magnet. When the current generated in the armature musl first pass through the field wind- ings before it reaches the external circuit the machine is said to be a series wound machine as shown at B because the armature and field windings are joined together in series. If only a portion of the current generated by the armature is directed to the field mag- net windings the machine is said to be shunt wound, as shown at C. A compound wound dynamo is shown at D. In this two sets of field windings are used, one connected in shunt, the other coils in series. The shunt winding provides an initial excitation sufficient to generate full voltage at no load. The series coils provide an excitation that increases as the load increases and thereby strengthen the field so as to prevent the falling off in voltage that would otherwise occur. If the series coils are sufficiently powerful to make the voltage rise as the load increases the machine is said to be over-compounded.
The compound wound dynamo is the type used almost univer- sally for direct current production. In stationary applications, compound wound motors are used where the load varies consider- ably under which conditions the extreme speed variation of series motors would be objectionable and where increased torque or turn- ing power would be needed that shunt motors could not give. A compound wound dynamo is, to a certain extent, self -regulating, as the two coils counteract each other and bring about a more regular action for varying currents than that of the ordinary shunt or series wound dynamo. The extent of the regulation possible depends upon the proportions of the different windings though a compound
Methods of Winding Dynamos
55
^Permanent Field Magnet
Pole Piece
N
/
External Circuit
t
^Armature Comutator
^i.M.>»»»a>__»a»J
i^a
Main
Circuit
SI
o
O
"♦«>
3 CO
N
M^
Lamps
/
Field Magnet
Armature
Comutator
B
Field Circuit
I
J{aJnJ)lrcuJt^^
^^^
Lamps
Fig. 18. — ^Diagram Showing Methods of Winding Dynamo. A — Simple Magneto Generator. B — Series Wound Machine. C — Shunt Wound Machine. D — Compound Typo.
' 56 Starting, Ldghting and Ignition Systems
"wound machine can be self -regulating at only one particular rota- tive speed. In a series wound dynamo short circuiting or lowering the resistance of ,the external circuit strengthens the field, thereby increasing the electro-motive force and the current strength. Some cut out means are usually provided to break the external circuit or to interpose added resistance to keep the current strength rela- tively constant and prevent injury to the windings by heating of the vrire and melting of the insulation. In a shunt wound dynamo the lowering of resistance on the outer circuit takes current from the field and lowers the electro motive force of the machine. Short circuiting has no heating effects. A compound wound machine combines, to a certain degree, the features of both the shunt and series wound dynamo. In a dynamo where the armature windings are grouped in coils which have independent terminals and which are not connected in series, the construction is termed * * open coil. * ' The terminals are attached to separate divisions of the commutator and are so spaced that the collecting brushes touch each pair be- longing to the same coil simultaneously. The brushes therefore take current from only one coil at a time. In a closed coil dynamo, the armature windings are connected in series and current is de- livered from all coils.
Electrical Terms Defined. — In referring to any force it is nec- essary to have some units by which its capacity may be judged. For instance, in comparing bodies of different size we can use units ' which will show the difference of mass or dimensions, such- as pounds or feet, or the fractions and multiples thereof. To gauge the ability of the electric force there are several practical units with which all motorists should be familiar. They are the volt, watt, ohm and ampere.
The VOLT is the practical unit of electro-motive force, pres- sure, or difference of potential or condition, existing between differ- ent parts of the circuit. Referring again to the reservoirs of water, we would find a foot height of liquid a very convenient ex- pression to use as a difference of height or head of water, and such is in constant use by all engineers. This is a precise analogy to the volt which is the unit that measures the tendency of an electric charge to escape to the opposite level, this being the actuating force
58 Starting, Lighting and Ignition Systems
such as a short length of a good conductor; others have so much as to form a most effectual barrier to the passage of the current, these being commonly known as insulators. As an example, con- sider a man lifting weights. The heavier the weight, the harder he must work to lift it. A little body weighing a few ounces offers so little resistance that it can be raised from the ground with a negligible amount of work. At the other hand it may have a mass
Fsed Wires
t
®OoooO<»
/\
Feed Wirea
Starting Bheostat
C
L
Field Winding-
Fig. 20. — ^Diagram Showing Electric Motor Windings. At Left — Series
Wound. At BigHt — Shunt Wound.
of several tons, in which case enough resistance would be offered to make it immovable against the efforts of one man, though a num- ber of men might easily move it without mechanical aid.
A substance that would offer considerable resistance to a current of low-tension or voltage would be easily overcome by a current having greater electro-motive force. For instance, it is impossible to pass the current obtained, from several cells of dry battery through the air gap between the points of a plug, as the current
60 Starting, Lighting and Ignition Systems
watts indicate an amount of electrical energy equal to one me- chanical horsepower.
Electrical Measuring Instruments. — As the electric force is intangible and is known only by its effects, it is necessary to have methods of measuring the amount employed to properly use the current. If the current was too strong injurious results might fol- low and if not strong enough satisfactory results could not be se- cured. The electric force can be measured by relatively simple devices. Most of the electrical measuring instruments depend upou the principle of electro-magnetism or induction and may be classi- fied as moving iron, moving coil, solenoid and plunger, magnetic vane, Jiot wire, inclined coil, etc. The four first named are the most commonly used in measuring the current employed in starting and lighting systems. These measuring instruments are made in port- able and switchboard types. The windings in an instrument de- signed to measure current quantity or amperage is usually of coarse wires, while the windings of an instrument to measure electro mo- tive force or voltage will be of finer wire. The gauge used to measure current quantity is called an ampere meter or ammeter while that used to measure current pressure is a volt meter.
The various forms of electrical measuring instruments and the method of operation may be readily understood by referring to the illustrations at Fig. 21. The instrument shown at A is known as a moving iron type. In this a permanent magnet holds a soft iron indicator to which the pointer needle is attached so that it registers with zero on the scale until a current passes through the coil and the magnetic lines of force thus produced tend to pull the needle in line with them and thereby actuate the pointer. The movement of the soft iron indicator depends entirely upon the amount of current passing through the coil. The moving coil pipe which is shown at B is the most popular form, as it gives the most reliable indication. The parts of a complete instrument of this form are clearly outlined at Fig. 22. This consists of a permanent magnet carrying a fixed pole piece about which a small solenoid capable of oscillating back and forth on jeweled bearings is mounted. On the cheap instruments ordinary pivot bearings are used instead of the jewels. A hand or pointer is pivoted at the
62 Starting, lAghUng and Ignition Systems
ceases to flow tbrough the solenoid. The function of the magnetic field is to heep the solenoid steady, thongh as soon as an electric carrent passes through its eqnilibrium is upset and the degree of movement is proportional to the amount or pressure of the cnrrent passing through it. Many small instruments which are accurate and inexpensive have been devised for testing current strength.
PFRMAUFNT
Tig. 22. — Diagram Showing OonBtniction of Moving Ooil T^pe Voltmeter.
For convenience the mechanism has been enclosed in standard watch movement cases in many instances.
The plunger type of indicator which is shown at C and D oper- ates on the principle of attraction that a solenoid exerts upon ma- terials susceptible to its influence. A curved plunger is used in that type usually intended for switch-board use. When a current is passed through the solenoid, the plunger is drawn into the in- terior of the coil, the amount of movement depending upon the current strength. This is indicated by a calibrated scale and
Electrical Measuring Instrumenta 6ft
pointer. The small battery tester which ia very simple in construc- tion works on exactly the same principle, except that the Tertical plunger which is drawn into the solenoid has the scale indicated upon it. The solenoid is kept pressed out against a stop by spring pressure which is overcome as soon as the current passes through the winding. The plunger type is not reliable for very small readings and is readily affected by any magnetic field in the vicinity.
The instrument shown at E is a magnetic vane type. In this a vane of soft iron is supported eccentrically or off center and when a current passes through the surrounding coil the vane is attracted toward the position where it will conduct the greatest number of lines of force, this movement actuates the pointer attached to the vane support and a hair spring ia used as in other instruments to re- turn the pointer to zero when the current flow
ceases and also to steady ^g 23.-Typi«Ll Dash Type Amperemeter the action of the instru- used with Modem UgbtlDg System,
meut. The small am-
peremetera are used only for testing dry cells, as the acale reads only to 30 amperes. This form of inatrument is also used as an indicator to show the rate of charge of a storage battery by the generator or current consumption of the lamps of the lighting system, ^he ordinary form of ammeter should never be used for teating storage cells and a voltmeter is necessary for tiiis pur- pose. Sometimes an amperemeter is so constructed with an in- ternal resistance that can be put in series with the solenoid coil that it will read voltage on another scale. Ah instrument thai
64 Starting, Lighting ajid Ignition Systems
+
POSmVE, SOMETIMES ABBREVIATED "/>"
NEGATIVE,SOMETIMES ABBREVIATED "N"
ARROW INDICATES DIRECTION OF CURRENT FLOW.
CLOCKWISE REVOLUTION.
PRIMARY.
COUNTER-CLOCKWISE REVOLUTION,
-VSA/-
COIL OF INSULATED WIRE. (COARSE.)
-lA/WWW-
COIL OF INSULATED WIRE. (FINE.)
®
AMMETER.
PUSH BUTTON OR LIGHTING SWITCH.
®
VOLTMETER.
STARTING SWITCH.
5
SHUNT WOUND MACHINE MOTOR OR GENERATOR.
MOTOR-GENERATOR 3-TERMINAL.
SERIES WOUND MACHINE MOTOR OR GENERATOR.
>+!
MOTOR-GENERATOR\ 4-TERMINAL.
<G>
GENERATOR.
CARBON OF DRY BATTERY.
<M>
MOTOR.
ZINC OF DRY BATTERY.
WIRES JOINED TOGETHER, SAME CIRCUIT.
WIRES CROSSING, SEPARATE CIRCUITS.
-^fmi
RHEOSTAT OR VARIABLE RESISTANCE.
— ^-
INCANDESCENT LAMP.
SECONDARY.
l|iP^
DRY CELLS OR STORAGE BATTERY. CELLS IN SERIES.
VOLT, UNIT OF POTENTIAL OR PRESSURE.
AMPERE, UNIT OF CURRENT QUANTITY.
D. C.
DIRECT CURRENT, FLOWS C0NTINUOULY AND ALWAYS IN ONE DIRECTION.
A. C.
ALTERNATING CURRENT, FLOWS FIRST IN ONE DIRECTION
THEN THE OTHER.
K.W.
KILOWATT. (1,000 WATTS).
H. P.
HORSEPOWER. (746 WATTS).
W
WA TT= ONE VOL T X ONE A MPERE.
GROUND CONNECTION.
HEA VY CABLE.
0=0
FUSE.
OCDOQCSIScD
BALLAST COIL .
®
PUSH BUTTON.
0=0
COWL LIGHT.
AUTOMATIC CUT-OUT.
Tig. 24.— Index to Signs, Symbols and Abbreviations Used in Wiring
Diagrams.
Electrical Measuring Instruments
65
will indicate 30 amperes and register up to eight volts has a range that is ample for all practical purposes. Some very low reading ammeters vrere formerly sold extensively as coil current consump- tion indicators, but with the passing of the vibrator coil ignition system they are no longer used to any extent.
I
I
CHAPTER II
BATTERY AND COIL IGNITION METHODS
How Compressed Gas May Be Ignited — ^Methods of Electric Ignition — Parts of Simple Ignition System — Induction Coil Action — Timers and Distrib- utors— Spark Plugs — ^Individual Coil System — ^Vibrator-Distributor Sys- tems— ^Master Vibrator Systems — Non- Vibrator Distributbr System — ^Lovr Tension Ignition — Double and Triple Ignition Systems — Battery Ignition System Troubles — Charging Storage Batteries — Care and Repair of Spark Plug Faults — Induction Coil — Timers — ^Wiring Troubles and Electro-static Effects — ^Timing Battery Ignition 'System.
How Compressed Gas May Be Ignited. — One of the most im- portant auxiliary groups of the gasoline engine comprising the automobile power plant and one absolutely necessary to insure en- gine action is the ignition system or the method employed of kin- dling the compressed gas in the cylinder to produce an explosion h,nd useful power. The ignition system has been fully as well de- veloped as other parts of the automobile, and at the present time practically all ignition systems follow principles which have become standard through wide acceptance.
During the early stages of development of the automobile vari- ous methods of exploding the charge of combustible gas in the cylinder were employed. On some of the earliest engines a flame burned close to the cylinder head and at the proper time for igni- tion, a slide or valve moved to provide an opening which permitted the flame to ignite the gas back of the piston. This system was practical only in the primitive form of gas engines in which the charge was not compressed before ignition. Later, when it was found desirable to compress the gas a certain degree before ex- ploding it, an incandescent platinum tube in the combustion cham- ber, which was kept in a heated condition by a flame burning in it, exploded the gas. The naked flame was not suitable in this appli
66
Methods of Electrical Ignition 67
cation because when the slide was opened to provide communica- tion between the flame and the gas the compressed charge escaped from the cylinder with enough pressure to blow out the flame at times and thus cause irregular ignition. When the flame was housed in a platinum tube it was protected from the direct action of the gas, and as long as the tube was maintained at the proper point of incandescence regular ignition was obtained.
Some engineers utilized the property of gases firing themselves if compressed to a sufficient degree, while others depended upon the heat stored in the cylinder head to fire the highly compressed gas. None of these methods were practical in their application to motor car engines because they did not permit flexible engine action which is so desirable. At the present time, electrical ignition sys- tems in which the compressed gas is exploded by the heating value of the minute electric arc or «park in the cylinder are standard, and the general practice seems to be toward the use of mechanical producers of electricity rather than chemical batteries used alone.
Methods of Electrical Ignition. — Two general forms of electri- cal ignition systems may be used, the most popular being that in which a current of electricity under high tension is made to leap a gap or air space between the points of the sparking plug screwed into the cylinder. The other form, which has been almost entirely abandoned in automobile practice, but which is still used to some extent on marine engines, is called the low-tension system because current of low voltage is used and the spark is produced by moving electrodes in the combustion chamber.
The essential elements of any electrical ignition system, either high or low tension, are : First, a simple and practical method of current production ; second, suitable timing apparatus to cause the spark to occur at the right point in the cycle of engine action; third, suitable wiring and other apparatus to convey the current produced by the generator to the sparking member in the cylinder.
The various appliances necessary to secure prompt ignition of the compressed gases should be described in some detail because of the importance of the ignition system. It is patent that the scope of a work of this character does not permit one to go fully into the theory and principles of operation of all appliances which
Starting, Lighting and Ignition Systems
Tig. 25. — simple Battery Ignition System f oi One-Oyllndei Uotor Show- ing Important Components and Tlieli Relation to Each Other.
may be used in connection with gasoline motor ignition, but at the same time it is important that the elementary principles be con- sidered to some extent in order that the reader should have a proper
70 Starting, Lighting and Ignition Systems
through the primary coil of the transformer. This magnetizes the core which draws down the trembler blade, this in turn separating the platinum contact point of the vibrator and interrupting the current. As soon as the current is interrupted at the vibrator the core ceases to be a magnet and the trembler blade flies back and once again closes the circuit between the platinum points. Every time the circuit is made and broken at the vibrator an electrical im-. pulse is induced in the secondary winding of the coil.
The vibrator may be adjusted so that it will make and break the circuit many times a minute and as a current of high potential is produced in the secondary winding with each impulse, a small spark will be produced between the points of the spark plug. The condenser is a device composed of layers of tin foil separated from each other by waxed or varnished paper insulation. It is utilized to absorb some of the excess current produced between the vibrator points, which causes sparking. This extra current is induced by the action of the primary coils of wire upon each other and by a reversed induction influence from the secondary coil.
If this current is not taken care of, it will impede the passage of the primary current and the sparks are apt to burn or pit the platinum contact points of the vibrator. When a condenser is pro- vided the extra primary current is absorbed by the sheets of tin foil which become charged with electricity. When contact is made again the condenser discharges the current in the same direction as that flowing through the primary coil from the battery and the value of the latter is increased proportionately. There is less sparking be- tween the vibrator points and a stronger current is induced in the secondary coil which in turn produces a more intense spark be- tween the points of the spark plug.
A typical induction coil such as would be used for firing a one- cylinder engine if used with a simple timer, or a multiple-cylinder engine if used in connection with a combined timer and distributor, is depicted in part section at Fig. 26. It will be observed that three terminal screws are provided on the box, one designed to be attached to the battery, the other two to the spark plug and ground, respec- tively. The terminal to which the battery wire is attached is coupled to the bridge member which carries the contact screw while
72 Starting, Lighting and Ignition Systems
PRimRY
fiommm
shown at Pig. 26, is a conventional one, though the connections will differ with the nature of the circuit of which the coil forms a part and the number of units comprising the coil assembly. When such devices are employed for igniting multiple-cylinder motors, the in- ternal wiring is very much the same as though the same number of
box coils for single-cyl- inder ignition were com- bined together by out- side conductors. The number of terminals provided will vary with the number of units.
Various forms of in- duction coils are de- picted at Fig.. 28. That at A is a simple unit form in which the coil is attached directly to the spark plug, which in turn is screwed into the cylinder. On this coil but two primary termi- nals are attached, one being connected to the insulated contact point on the timer, the other being grounded, or at- tached to the battery. Coils of this type have been very popular in marine application because of the simple and direct wiring possible, but they have not been used in connection with automobile engine ignition to any extent. The form shown at B is a simple dash coil for one- cylinder use which has three terminals, one being used for a secondary lead to the spark plug, the other two being joined to the battery and ground respectively, as shown at Fig. 26.
The form of coil shown at C is a two-unit member designed for double-cylinder ignition. As the switch is mounted on the coil box
T\%. 27. — ^Tliree Terminal Box Coil for Single Cylinder Engine Ignition.
74 Starting, Lighting and Ignition Systems
to use two sets of batteries, six terminals are provided on the bottom of the coil case. Two of these are attached directly to the insulated contact point of the timer; two others which are enclosed in hard rubber insulatiag caps are attached to the spark plugs. The two immediately under the switch are attached to the free terminals of the battery, two sets being provided, one being coupled to each side of the switch.
With a four-unit coil, as shown at D, ten terminals are provided because of the attached switch. Four go to the spark plugs, four to the insulated segments of the timer and two to the battery, or bat- tery and magneto or dynamo, as the case may be. In modern coils the units may be removed from the box without disturbing any internal connection, and a new one slipped in its place if it does not function properly. Special care is taken in insulating the high- tension terminal by means of rubber caps which surround the wire, and care is taken to have the vibrator contact points readily acces- sible for inspection, cleaning, or adjustment.
Action of High Tension Coil Ignition . System. — Another ex- planation of the action of the conventional induction coil and bat- tery system may enable the reader to obtain a clearer understanding of the action of the transformer coil system of intensifying cur- rent and can be read to advantage to supplement the explanation previously given. Another diagram. Fig. 29, shows a four terminal coil unit instead of the three terminal coil diagram outlined at Fig. 25, and differs in that the primary and secondary circuits have separate ground connections instead of having a common ter- minal on the coil. As the internal construction of the induction coil has been previously described, it will be merely necessary to review the action of the complete ignition system outlined.
In the diagram shown the action is as follows : When the switch E is closed and the rotor (f ) of the spark-timing device D comes in contact with the terminal (g), the current flows from the positive terminal (m) of the battery to the switch E. From thence to the primary terminal (h) on the coil ; and through the vibrator spring (e) across the points (o) which are in contact, to the adjusting screw (i) and into the bridge which supports the adjusting screw. The primary winding (b) is attached to this bridge at (j) and
76 • Starting J Lighting and Ignition Systems
The vibrator is composed of a piece of spring steel with a small iron button riveted to the end of it. When the circuit is complete and the core is magnetized it attracts the iron button and breaks the contact of the points at (o), thus interrupting or opening the circuit and preventing further jSow of the current. The core then loses its magnetism and the vibrator spring pulls the button back ;and again brings the points in contact to again complete the cir- cuit. This occurs about one hundred times per second and the rapid vibration produces a pronounced buzzing sound 'at the vi- brator.
When the points (o) are in contact and the core is magnetized a very strong magnetic field flows across the wire of the secondary winding (c). When the field becomes strong enough to attract the vibrator button the circuit is broken and the current sto{)s flowing. As soon as the current ceases to flow and^ the magnetic field or force becomes reduced in intensity, a strong or high voltage cur- rent is produced in the secondary winding. This current flows to the spark plug F from the secondary terminal of the coil (s) and it has sufficient power to jump the air gap at (p), causing a spark. The spark plug construction is such that after jumping the air gap the secondary current will flow back to the engine and from the ground terminal (1) to the terminal (t) and then back through the secondary winding to the terminal (s) from which it started.
The magnetic field dying down has thus produced an induced current in the secondary winding, and in addition it will also set up a self -induced current in the primary winding. As the break in the primary circuit is made at the vibrator points, a large spark would occur there and very soon bum them away. To absorb the extra current which causes this spark a condenser is connected across the points by the wires (v) and (w). When the circuit is opened at (o) the self -induced current of the primary winding flows in the same direction as the original battery current. As the condenser has less resistance than the air gap which this current would have to jump at (o) it absorbs the current, and immediately that the condenser is charged, it discharges. The. contact points (o) of the vibrator being separated at this time, the current from the condenser cannot pass through them to get to
78
Starting, Lighting and Ignition Systems
the revolving member of the timer turns at engine speed, and should be driven directly from and at the same speed as the crank shaft.
Simple timer forms suitable for one-cylinder motors are shown at Fig. 30. The simplest one, depicted at A, consists of a rocking member of fiber or other insulating material which carries a steel spring that is normally out of engagement with the surface of the cam. When the point of the cam brushes by the contact spring,
Contact ''Spring
Contact Points
Fig. 30. — Simple Forms of Contact Breakers or Timers Used on One Cylinder Engines. A — ^Wipe Contact. B — ^Touch Contact.
any circuit in which the device is incorporated will be closed and current will flow from the battery or dynamo to the transformer coils and spark plugs which are depended on to furnish a spark of sufficient intensity to insure ignition of the gas. It is desirable that the member which carries the contact spring be capable of a certain degree of movement, in order that the spark time may be advanced or retarded to suit various running conditions. In the form shown if the top of the casing is pushed in the direction of the arrow, the contact spring will come in contact with the point of the cam which is turning in the direction indicated sooner than
80 Starting, Lighting and Ignition Systems
A secondary distributor which is employed to distribute both liigh and low tension current is shown at Fig. 31, B. This consists of a primary timing arrangement in the lower portion, and a secondary current -distributing segment at the upper portion. The central revolving member carries as many rolls as there are cylin- ders to be fired, these being spaced at the proper points m the
Fig. 31. — Timers Employed on Fonr Cylinder Engines. A — Fonr Contact Device for Oomrantatltig Primary Onrrent. B — Combined Timer and DUtrllmtor, Directs Botb High and IiOw Tension Energy,
circle to insure correct timing. One primary contact member is screwed into the casing, this contacting with the rolls as they revolve. At the upper portion rf the ease a number of terminals are inserted from which wires lead to plugs in the cylinders. When a timer of the form shown at A is used, a separate induc- tion coil is needed for each cylinder and the number of units in the coil box and contact points on the timer will be the same as the number of cylinders to be fired. "When a secondary distributor
82 Starting^ Lighting and Ignition Systems
central hollow revolving member. Some timers of the form shown at Fig. 31, A, are fitted with a plain bearing which wears after the timer has been used and which produces irregular ignition due to a poor ground contact. Battery timers of the forms out- lined are seldom used at the present time, as they have been suc- ceeded by the more efficient short contact types. A notable excep-
Fig. 32. — Showing Disposition of Contact Points on Timers for Differing Numbers of Cylinders. A — One Cylinder Type. B — ^Arrangement of Two Cylinder Opposed Motor. C — Contacts Separated by 90 De- grees in One Direction and 270 Degrees in the Other when Used on a Two Cylinder Vertical Engine with Opposed Crank Pins. D— Three Cylinder Form. E — Spacing for Four Cylinder Engines. F — Type Employed on Six Cylinder Power Plant.
tion to this almost general rule is the Ford car, which is manu- factured in immense quantities and which utilizes the roller con- tact timer previously described.
One of the best known of the short contact forms of timer is the Atwater-Kent, which is usually combined with a secondary distributor as shown at Fig. 35. The method of placing this timing and distributing member in circuit is clearly shown in
84
Starting, Lighting and Ignition Systems
interrupter, the other to a grounding screw attached to the inter- rupter casing. The secondary terminal is connected to the central terminal of the distributor, while the remaining four terminals are joined to the plugs in the engine cylinders in such order as to insure proper sequence of explosions. The external view of the Atwater-Kent uni-sparker is shown at Fig. 35, A. In this a centrifugal mechanism is contained in the lower Dart of the
Co//
1
D/str/buter to Cot/
Un/spar/cer
/nterrupter to Coi/
Ground to Coi/
Tig, 34 — ^Wiling Diagram of Atwater-Kent Uni-Sparker.
casing by which the spark is automatically advanced as the speed of the engine increases.
The only points that will wear on a device of this character are the contact points which are clearly shown in the view of the contact breaker mechanism at Fig. 36. The revolving shaft in the center has a number of notches, two, three, four, six, or eight, according to the number of cylinders to be fired, cut into it. A light, hardened steel trigger, B, is held against the shaft at this point by a small spring. On turning the shaft this trigger is carried forward by the notches in the shaft, and is suddenly released as the hook end leaves the notch. In so doing the back of the trigger
Atwater-Kent Um-Sparker 85
strikes a small pivoted hammer, D, situated between the trigger and the spring carrying the contact points. This causes the contact points, K, to open and close with remarkahle rapidity, but one con- tact being made for each spark. When it is desired to adjust the platinum contact points, as when they show signs of wear, it is only necessary to remove one or more of a number of extremely thin washers under the head of the adjustment screw and to replace
Fig. 35. — Showing Oonstniction of Atwater-Kent Uni-Sparker.
the screw. The contact points should be absolutely clean and bright and have smooth contacting surfaces. The distributor por- tion of the device consists of a hard rubber block fitted to the top of the primary shaft, this carrying a brass quadrant that passes the high tension current to the spark plugs by means of the terminal points imbedded in the hemispherical cover. There is no actual contact between the rotating quadrant and the distributor points, as the high tension current is capable of jumping the very
Starting, Lighting and Ignition Systems
Fig. 36, — Diagrams Explaining Action of Atwater-Eent Conta-tA, Breakei'.
alight gap that exists between them. Owing to there being no act- ual contact, there will be no depreciation in the distributor or upper portion. The center terminal, which is in connection with the induction coil, is a combination of carbon and brass, and a
Delco Battery Ignition System 87
light, flat spring on the quadrant bears against it to maintain positive electrical connection. The distributor cover is easily re- moved without the use of tools, as it is held by spring clips. Location or dowel pins in its lower edge insure that it will be replaced in the correct position.
One of the most popular of the combined starting, lighting and ignition systems is the Delco, which is shown at Fig. 37. For the present we will concern ourselves merely with discussing the ignition functions of the system, leaving the self-starting and electric lighting features for more comprehensive -consideration later. Current is produced by a one unit type motor-generator, although the windings of the device when operated as a motor or a generator are entirely separate. The ignition current is obtained either from a storage battery which is kept in a state of charge by the generator, or from a set of dry cells which are carried for reserve ignition. The ignition system consists of a one unit non- vibrator coil, sometimes attached to the top of the motor generator, though it may be placed at any convenient part of the car and a dual automatic distributor and timer usually included as a part of the device as shown. "When ignition current is supplied frop the lighting circuit the current passes from the storage battery through a switch and out to the low tension winding of the coil, from whence it passes to the timer and from there to the frame, where it is grounded. The high tension current generated in the coil runs to the distributor, where it is switched to the spark plug in the different cylinders in turn.
When dry cells are used for ignition the operation is the same except that a device called **the ignition relay,'' and shown at the right of Fig. 38, is added to the circuit. The function of this device is to break the circuit immediately after it has been completed by the contact points of the timer, which is shown at the left. The use of the ignition relay results in a material saving of the battery current as the circuit is closed a much shorter time than is the case when the circuit is broken by the timer contacts themselves. The operation of the relay is not difficult to under- stand. The magnet A attracts the armature B when the circuit is completed through the timer. This action opens contact C and
Starting, Lighting and Igmtion Systems
Action of Delco Ignition System 89
breaks the timer circuit. A condenser D is mounted besides the magnet coil A, in order to absorb the current produced by self- inductio.i in the magnet winding, which would be apt to produce a hot spark between the contact points when they were separated if no means were taken for its disposal. The adjustment of the relay is at the pole piece E. This regulates the distance between the armature B and the mftgnet pole, and the gap between the contacts C. The adjustment is made by turning the notched head at E clockwise to increase, anti-clockwise to decrease, the gap be- tween the contacts.*. The correct distance between contacts C when the armature B is pressed down is equal to approximately the thickness of one sheet of newspaper. A very simple way in which the adjustment can be made when the engine is running on the battery is to turn the notched head of the pole piece in the counter- clockwise direction until the motor ceases to fire. Then turn it four or five notches in the opposite direction. Under no condi- tions should the adjustment screw be turned very far in either direction. If the armature vibrates feebly when the starting but- ton is pressed it indicates either weak dry cells or dirt between the relay or timer contacts.
The interior arrangement of one form of timer for both dry cells and storage battery current is shown at Fig. 38. The cam C is driven by a rotating shaft and establishes contact between the points when the cam rider rises on the point of the cam. "When the cam rider drops into the notch between the high points the contact points separate. The same instructions that have been given for the contact points of the Atwater-Kent timer apply just as well in this case. While the contact points are but one-eighth inch in diameter, it is said that many thousands of miles of service may be obtained without readjusting. It is important that the contact spring, which is the straight one carrying the platinum point, should have a good tension outward against the cam rider member below it. It is said that this spring should be capable of supporting the weight of half a pound. If the tension is not sufficiently great the contact points barely break contact which permits the spark to arc between them, tending to burn them. The contact should be so adjusted that the contact spring is
90 Starting, Lighting and Ignition Systems
forced away from the breaker member at least half the distance of the T-slot on the vertical part of the earn rider, when the latter is on the contact lobe of the cam. The contact points should open abont ten one-thousandths (.010 inch) inch when the contact arm rests upon the back stop. The contact arm should clear the cam except at the contact lobe. A short wire connects the two posts
Fig. S8. — Selco Pilmarr Timer at Left and IgnlUon Belaf at Blgbt
of the breaker arms and this connection should always be inspected when making adjustments to insure that it has not been disturbed. It is said that if this wire is disconnected the current will pass through the contact spring, impairing its tension. Whenever the contact points are cleaned care should be taken to have the sur- faces parallel.
In some of the Delco ignition Eiystems an automatic spark ad- vance mechanism is nsed. The usual method of wiring when the distributor is a separate member from the generator is shown at A, the left of Pig. 39. The construction of the automatic spark vanee mechanism is shown at B, In this the shaft which trans-
Delco Automatic Spark Advance 91
mits motion to the timer is in the foVm oi a tube T, revolved by spiral gears. An inclined slot is cut through the walls of this hol- low driving member. A smaller shaft is carried inside of the hollow member, and a vertical slot is cut through this shaft in order to permit a pin to pass through it, said pin being actuated by a collar adapted to slide up and down on the outside of the hollow driving shaft. The pin passes through both the straight
Fig. 39. — ^Parts of Delco 1911 S78t«n. A — Delco Timer, Coll and Con- denset AsaemMy. B — Oonstmction of Delco Automatic Spark Ad- vance. C — Delco Voltago Begnlator.
slot in the small shaft -ftid the incline slot in the hollow driving member. If the collar holding the pin is moved it will change its angular relation with the small shaft which will advance the tim- ing cam of the contact breaker. The collar is shifted by a spring loaded revolving ring R, which moves from the position shown in the drawing to a horizontal position as the speed increases. This ring is eonnec'.«d to the sliding collar and causes it to rise, ad- vancing the spark as the engine speeds up or to fall, retarding the spark as the engine speed decreases. If desired, the spark
92 Starting, Lighting and Ignition Systems
timing may be controlled inSependently of the automatic advance mechanism by a spark lever connected to the corresponding mem- ber on the steering wheel. The voltage regulator, which will be described when discussing the generating function of the Delco instrument, is shown at Fig. 39, C.
Condenser. — The condenser consists of two long strips of folded tinfoil insulated from each other by paraffined or oiled paper, and connected as shown in Fig. 40. The condenser has the property of bdng able to hold a certain quantity of electrical energy, and like the storage battery, will discharge this energy if there is any circuit between its terminal. As the distributor contacts open the magnetism commences to die out of the iron core, this induces a voltage in both the primary and secondary windings of the coiL This induced voltage in the primary winding amounts to from 100 to 125 volts. This charges the condenser which immediately dis- charges itself through the primary winding of the coil in the reverse direction from which the ignition current originally flows. This discharge of the condenser causes the iron core of the coil to be quickly demagnetized and remagnetized in the reverse direction, with the result that the change of magnetism within the secondary winding is very rapid, thus producing a high voltage in the second- ary winding which is necessary for ignition purposes. In addition to rapidly demagnetizing the coil the condenser prevents sparking at the breaker contacts — thus it is evident that the action of the condenser can very seriously affect the amount of the spark from the secondary winding and the amount of sparking obtained at the timer contacts.
Ignition Coil. — This is sometimes mounted on top of the inotor generator and is what is generally knowh as the ignition trans- former coil. In addition to being a plain transformer coil it has incorporated in it a condenser (which is necessary for all high tension ignition systems) and has included on the rear end an ignition resistance unit. The coil proper consists of a round core of a number of small iron wires. Wound around this and insulated from it is the primary winding. The circuit and arrangement of the different parts are shown in Fig. 41. The primary current is supplied through the combination switch and resistance on the
Delco Ignition System Parts 93
coil, through the primary winding, to the distributor contacts. This is very plainly shown on the circuit diagram. It is the inter- rupting of this primary current hy the timer contacts together ■with the action of the condenser whi^ causes a rapid demagnetiza^ tion of the iron core of the coil that induces the high tension current in the secondary winding. This secondary winding consists of sev-
OOBTAOT 18 OROOHMD
^
I
Tig. 40. — Simplified Wiring Diagram Sliowliis Action of Delco Ignition System.
eral thousand turns of very fine copper wire, the different layers of which are well insulated from each other and from the primary winding, one end of which terminates at the high tension terminal about midway on top of the coiL It is from this terminal that the high tension current is conducted to the distributor where it is dis- tributed to the proper cylinders by the rotor shown in Pig. 42.
Ignition Besistance TTnit. — The ignition resistance unit which is shown in Fig. 41 is for the purpose of obtaining a more nearly
94 Starting, Lighting and Ignition Systems
auiform current through the primary winding of the ignition coil at the time the distributor contacts open. It consists of a number of turns of iron wire, the resistance of which is consider- ably more than the resistance of the primary winding of the ignition coil. If the ignition resistance unit was not in the circuit and the coil was so constructed as to give the proper spark at high speeds, the primary current at low speeds would be several times its normal value with serious results to the timer contacts. This is evident from the fact that the primary current is limited by the resistance
^"L^TP^l^ Til^lNALS msT
Fig. 41. — Sectional View Showing ArrEiDgement of Wiring In Delco Ignition Coll.
of the coil and resistance unit by the impedence of the coil. (Im- pedence is the choking effect which opposes any alternating or pul- sating current magnetizing the iron core.) The impedence increases as the speed of the pulsations increase. At low speeds the resistance of the unit increases, due to the slight increases of current heating the resistance wire.
The Circuit Breater. — The circuit breaker is mounted on the combination switch as shown in Fig. 42, This is a protective device which takes the place of a fuse block and fuses. It prevents the discharging of the battery or damage to the switch or ■wiring
Delco Ignition System Parts
95
to the lamps, in the event of any of the wires leading to these becoming grounded. As long as the lamps are using the normal amount of current the circuit breaker is not affected. But in the event of any of the wires becoming grounded an abnormally heavy current is conducted through the circuit breaker, thus producing a strong magnetism which attracts the pole piece and opens the con-
O LIGHTING IGN. DELCO
oOOOO
h 0
CiircuiT ff/i^e^fce/r
HunaeF^ Ofloy^£/fT£R/1lNAL9
Fig. 42. — ^Delco Combination Switch with Ammeter and Circuit Breaker
Included.
tacts. This cuts off the flow of current which allows the contacts to close again and the operation is repeated, causing the circuit breaker to pass an .intermittent current and give forth a vibrating sound. It requires 25 amperes to start the circuit breaker vibrating, but once vibrating a current of three to five amperes will cause it to continue to operate. In case the circuit breaker vibrates re- peatedly, do not attempt to increase the tension of the spring, as
96 Starting^ Lighting and Ignition Systems
the vibration is an indication of a ground in the system. Remove the ground and the vibration wUl stop.
The Ammeter. — The ammeter on the right side of the combina- tion switch is to indicate the current that is going to or coming from the storage battery, with the exception of the cranking current. When the engine is not running and current is being used for Ughts, the ammeter shows the amount of current that is being used and the ammeter hand points to the discharge side, as the current is being discharged from the battery. When the engine is running above generating speeds and no current is being used for lights or horn, the ammeter will show charge. This is the amount of current that is being charged into the battery. If current is being used for lights, ignition and hor» in excess of the amount that is being gen- erated, the ammeter will show a discharge as the excess current must be discharged from the battery, but at all ordinary speeds the ammeter will read charge.
Construction of 1916 Delco Ignition Distributor. — It is well understood that a rich mixture burns quicker than a lean one. For this reason the engine will stand more advance with a half open throttle than with a wide open throttle, and in order to secure the proper timing of the ignition due to these variations and to re- tard the spark for starting, idling and carburetor adjusting, the Delco distributor also has a manual control. The automatic fea- ture of this distributor is shown in. Fig. 43. With the spark lever set at the running position on the steering wheel (which is nearly all the way down on the quadrant), the automatic feature gives the proper spark for all speeds excepting a wide open throttle at low speeds, at which time the spark lever should be slightly retarded. • When the ignition is too far ad- vanced it causes loss of power and a knocking sound within the engine. With too late a spark there is a loss of power (which is usually not noticed excepting by an experienced driver or one very familiar with the car), and heating of the engine and excessive consumption of fuel is the result. The timer contacts shown at D and C (Fig. 43) are two of the most important points of an automobile. Very little attention will keep these in perfect con- dition. These are of tungsten metjal, which is extremely hard and
Delco Ignition System Parts
97
requires a very high temperature to melt. Under normal condi- tions they wear or bum very slightly and will very seldom require attention; but in the event of abnormal voltage, such as would be obtained by run- ning with the battery removed, or with the ignition resistance unit shorted out, or with a defective condenser, these contacts bum rapidly and in a short time will cause serious ignition trouble. The ear should not be oper- ated with the battery removed.
It is a very easy matter to check the re- sistance unit by observ- ing its heating when the ignition button is out and the contacts in the distributor are closed. If it is shorted out it will not heat up, and will cause missing at low speeds. A de- fective condenser such as will cause contact trouble will cause serious missing of the ignition. Therefore, any one of these trou- bles is comparatively easy to locate and should be immediately- . remedied. These contacts should be so adjusted that when the fiber block B is on top of one of the lobes of the cam the contacts are Opened the thickness of the gauge on the distributor wrench. Ifcdjust contacts by turning contact screw C and lock with nut N. the contacts should be dressed with fine emery cloth so that tbey-
Flg. 43.— SbffwiDg Oonsttuction of 1916 Delco Distributor for Six Cylinder IgniUon. Not« Six IaIm Cam.
98 Starting, Lighting and Ignition Systems
meet squarely across the entire face. The rotor distributes the high tension current from the center of the distributor to the proper cylinder. Care must be taken to see that the distributor head is properly located, otherwise the rotor brush will not be in contact with the terminal at the time the spark occurs.
Combination Switch, — The combination switch is located on the cowl board and makes the necessary connections for ignition and
Fig. 44. — Delco Coiiitiina,tlon Switch without Amperemeter Showtng Headlight Dimmer BesiBtmice.
lishts. The " M " button controls the magneto type ignition and the " B " button, the dry battery ignition. In addition to this both the " M " and " B " buttons control the circuit between the generatoi and storage battery. When the circuit between the fcenerator and the storage battery is closed by either the " M " or " B " buttoB on the combination switch, the direction of flow of the current ii from the battery to the generator when the engine is not running
Delco Ignition System Parts
09
as well as when it is running below 300 R. P. M. But the amount of current that flowa from the battery at the lowest possible en^e speeds is so small that it is negligible. That used on Bniek 1915 cars is shown at Fig. 44, the type supplied on 1916 cars is out- lined at Fig. 42.
To Time the Igni- tion.— 1. Fully retard the spark lever, 2. Turn the engine to mark on flywheel about one inch past dead center to the "7 degree" line, with No. 1 cylinder on the fir- ing stroke. 3. Loosen screw in center of tim- ing mechanism (Pig. 45) and locate the proper lobe of the cam by turning until the
Tig. 16. — ^How Cover is Bemwed from Delco Dlstribntor.
100 Starting^ Lighting and Ignition Systems
button on the rotor comes under the high tension terminal for No, 1 cylinder. 4. Set this lobe of the cam so that when the back lash in the distributor gears is rocked forward the timing contacts will be open, and when the back lash is rocked backward the contacts WILL JUST CLOSE. Tighten screw anA-replace rotor and distributor head. The construction of the distributor head is clearly shown at Fig. 42, which shows the internal view, while Fig. 46 shows the exterior and plan of contact brushes.
Ignition Terminpis %
DisintMjfx>r * Phfe
Swiich 'bTttinat
s
Irrherrupftr Cover
Dtsiribuior ^ Plate
Inofucfhn Coiii
D&trk/ior^ dhJsh-Atm.
Distributor drush
Fiber pumper^^
Interrupfer : Contacts
Coniacts
Adjusting
Screw
ConoKosef
^^Jnterrupter
Cam
Tig, 47.— ^Parts of Westinghouse Timer-Distributor, wMch Includes the
Induction Coil.
V.
Westinghouse Vertical Ignition Unit. — The WeSfinghouse ver- tical ignition unit, shown at Fig. 47, can be used for ignition from storage batteries or plain lighting generators. This set contains, interrupter, spark coil and condenser, and distributor, all in one unit. One wire from the battery or generator to the ignitiQii unit and one wire to each spark plug are all that are required — the simplest possible connections. The interrupter, located at the lower end of the set, has the same type of circuit-breaker as that
Westinghouse Ignition Unit
101
>n the Westinghouse ignition and lighting generators, but no iutomatie spark advance feature. It can be used equally efficiently for either direction of rotation without change. The interrupter s enclosed by a spring jollar which can be readily removed for inspection or adjust- ment of the contacts. The collar makes a tight joint and is 2lamped by a screw which prevents it from slipping. The spark ;oil is embedded in seat - proof insulating material, ind the con- Jenser is well insu- lated. Both are con- tained in a tube of Bakelized M i c a r t a which forms the body if the unit. The dis- tributor is of very simple construction rt'jth a wiping brush contact of the same type as that used on the ignition generat- , ars. .It clamps to the upper end of the set. The wiring diagram of this system is shown at Fig. 48. The device is sometimes mounted in connection with a generator when that member is driven by direct gear connection from cam shaft which provides a properly timed drive for the ignition unit. This method of application is clearly shown at Fig. 49.
rig. 48. — Sbowlng iDtenuil Wiring of West- luglioase Timer-Distrlbutoi and Coll Igni- tion Unit.
102 Starting, Lighting and Ignition Systems
Spark Plug Design and Application. — With the high-tension system of ignition the spark is produced by a current of high voltage jumping between two points which break the complete circuit, which would exist otherwise in the secondary coil and its external connections. The spark plug is a simple device which consists of two terminal electrodes carried in a suitable shell mem- ber, which is screwed into the cylinder. Typical spark plugs are shown in section at Figs. 50 and 51, and the construction can be , easily understood. The
secondary wire from the coil is attached to a terminal at the top of a central electrode member, which is sup- ported in a bushing of some form of insulat- ing material. The type shown at A employs a molded porcelain as an insulator, while that depicted at D uses a bushing of mica. The insulating bu&hing and electrode are housed in a steel body, which is provided with a screw thread at the bottom, by which it is screwed into the com- bustion chamber.
When porcelain is used as an insulating material it is kept from direct contact with the metal portion by some form of yield- ing packing, usually asbestos. This is necessary because the steel and porcelain have different coefficients of expansion and some flexibility must be provided at the joints to permit the materials to expand differently when heated. The steel body of the plug which is screwed into, the cylinder is in metallic contact with it and carries sparking points which form one of the terminals of the air gap over which. the spark occurs. The current entering
Spark Plug Construction
ijaat-wirt L«op
rig. 60. — Sectional Views Shoving Conatruction of Typical Spark Plugs.
104 Starting^ Lighting and Ignition Systems
at the top of the plug cannot reach the ground, which is repre- sented by the metal portion of the engine, until it has traversed the full length of the central electrode and overcome the resistance of the gap between it and the terminal point on the shell. The porcelain bushing is firmly seated against the asbestos packing by means of a brass screw gland which sets against a flange formed on the porcelain, and which screws into a thread at the upper portion of the plug body.
The mica plug shown at D is somewhat simpler in construction than that shown at A. The mica core which keeps the central electrode separated from the steel body is composed of several layers of pure sheet mica wound around the steel rod longitu- dinally, and hundreds of stamped mica washers which are forced over this member and compacted under high pressure with some form of a binding material between, them. Porcelain insulators are usually molded from high grade clay and are approximately of the shapes desired by the designers of the plug. The central electrode may be held in place by mechanical means such as nuts, packings, and a shoulder on the rod, as shown at A. Another method sometimes used is to cement the electrode in place by means of some form of fire-clay cement. Whatever method of fastening is used, it is imperative that the joints be absolutely tight so that no gas can escape at the time of explosion. With a mica plug the electrode and the insulating bushing are really a unit construction and are assembled in permanent assembly at the time the plug is made.
Other insulating materials sometimes used are glass, steatite (which is a form of soapstone), and lava. Mica and porcelain are the two common materials used because they give the best results. Glass is liable to crack while lava or the soapstone insulating bush- ings absorb oU. The spark gap of the average plug is equal to about Vi6 of an inch for coU ignition and from i/64 to 1/32' of an inch when used in magneto circuits. A simple gauge for deter- mining the gap setting is the thickness of an ordinary visiting card for magneto plugs, or a space equal to the thickness of a worn dime for a coil plug. The insulating bushings are made in a number of different ways, and while details of construction vary,
Spark Plug Construction
106 Starting^ Lighting and Ignition Systems
spark plugs do not differ essentially in design. Pour different forms of plugs using porcelain insulation are shown in part sec- tion at Fig. 51. Porcelain is the material most widely used be- cause it can be glazed so that it will not absorb .oil, and it is subjected to such high temperature in baking that it is not liable to crack when heated.
The spark plugs may be screwed into any convenient part of the combustion chamber, the general practice being to install them in the caps over the inlet valves, or in the side of the combustion chamber, so the points will be directly in the path of the entering fresh gases from the carburetor. The methods of spark plug in- stallation commonly used are shown at Fig. 52. At A the plug is screwed into a threaded hole which passes through the valve cap in such a manner that the points are in a pocket. This is not considered to be as good as the method depicted ^t B, where the interior of the valve cap is recessed out so there is consid- erable clear space around the spark points. When the electrodes are carried in a pocket they are more liable to become short cir- cuited by oil or carbon accumulations, because it is difficult for the fresh gases to reach them and the pocket tends to retain heat. Ignition is not so certain because some of the burned gases may be retained in the pocket and prevent the fresh gas from getting in around the spark gap. With a recess, as shown at B, condi- tions are more favorable because the fresh gases can sweep the points of the spark plug and keep them clear, and also because of the larger space any burned products retained in the cylinder are not so apt to collect around the plug point. The method of installation shown at C causes the plug to heat and is not as efficient as that outlined at D, which permits ready transference of heat to the cooling water in the jacket spaces.
On some types of engines which are not provided with com- pression relief, or priming cocks, plugs are sometimes installed, as shown at Fig. 51, C. A special fitting, which carries a priming cup at one side, is screwed into the cylinder and the spark plug is fitted to its upper portion. When it is desired to relieve the compression, the valve portion is turned in such a way that a passage is provided from the interior of the fitting to the outer air.
Spark Plug Construction
Fig. 62. — Illustrations Showing Proper and Impioper Placing of Spark Plugs.
At the same time when the valve ia in the position shown in illus- tration, gasoline may be introduced into the cylinder for priming purposes. It is advanced that this method of constraction also provides a simple means of freeing the plug points from oil ot particles of carbon if the cock is opened while the engine is running. The high pressure gas which brushes by the points on
108 Starting, Lighting ajid Ignition Systems
its way out of the cylinder tends to dislodge any particle of foreign matter which may be present near the spark gap. The same objections apply to this method of mounting as to that illustrated at A.
Some spark plugs have been designed \Hth a view of per- mitting one to see if the charge is being exploded regularly in the cylinder by some form of transparent material for insulation, so that the light produced by the explosion could be seen from the outside of the cylinder. The simplest method of determining if a spark is occurring regularly between the points is to use some form of spark gap which is interposed between the source of cur- rent and the plug terminal. A device of this nature is shown at Fig. 51, G. It consists of a body of insulating material which carries in a glass tube two points, which are separated by a slight air space. The eye or hook end is attached to the plug terminal, while the other end is attached to the secondary wire. If the current is passing between the points of the plug, a spark will take placiB between the points of the auxiliary spark gap every time one occurs between the points of the plug in the cylinder.
It is claimed that there are certain advantages obtained when a spark gap is used in the circuit, in that the spark in the cylinder is more effective and less liable to be short circuited by particles of foreign matter. At the other hand, others contend that the current must be stronger to jump two gaps than would be re- quired if only the resistance of one was to^be overcome. While very popular at one time, the spark gap is of rather doubtful utility and is seldom used at the present time, except as a means of indicating if spark has taken place between the points of the spark plug. It is apt to be somewhat misleading, however, be- cause even if the points of the plug are short circuited and no spark is taking place between the plug points, and yet current is passing to the ground, a spark will continue to take place at the auxiliary spark gap. The device is useful in showing when there is a break or derangement of the wiring or coils. *'"*
A form of spark plug having glass bull's-eyes set into the plug shell or body is shown at Fig. 51, H. These simple lenses are made nf specially compounded glass, which has a high resistance to heat
110 Starting, Lighting and Ignition Systems
is not so apt to be short circuited by soot as the projecting elec- trode forms are, and that the spark tends to clear away material that might short circuit the current by burning it.
The plugs shown at D and E have mica insulators instead of porcelain. When mica is used a sheet of that iiaterial is wrapped around the central electrode several times, after which a series
111=131
I^g. 63. — CoaTsntloual Tjrpe Of Spaik Plug aX A, Showing All Gap Be- tween the Points. B — Prlmlag Plugs. C — Two-Point Spark Plug.
of mica washers is clamped tightly together and turned down to form a smooth insulator. The plug at F is the only one mar- keted using glass insulation. Other plug forms made on the same general principles as that at A use lava or steatite as an insu- lator instead of the porcelain or mica. For all-around service the porcelain insulator gives the best results, as the mica and lava insulators are apt to become oil soaked and permit the current to short circuit through the insulator and the plug body instead
Spark Plug Construction 111
of jumping the air gap. Another representative form of spark plug showing the proper space between the spark points is shown at Fig. 53, A.
The plug at Fig. 53, B, is one that combines a priming feature and is intended for use in engines of the Ford type in which no pro- vision is made for using priming cups or compression relief cocks. The plug body is formed in such a way that a needle valve fitting may be screwed into it, this being intended to close a passagieway communicatinjg from a channel around the top of the plug body to the interior of the plug body. It is said that if this needle valve is opened for a minute or so while the engine is running that there will be a tendency to clear the plug points of any loose oil or carbon. The compression may be relieved by opening the needle valve, and if it is desired to inject gasoline into the cylinder to promote easy starting this may be easily done by filling the channel or groove on top of the plug body with the fuel, then opening the needle valve to allow it to pass to the plug interior. The gasoline will run down the walls and collect around the spark points, where it will be readily ignited by the spark.
Plugs for Two-Spark Ignition. — On some forms of engines, especially those having large cylinders, it is sometimes difiicult to secure complete combustion by using a single-spark plug. If the combustion is not rapid the efiiciency of the engine will be reduced proportionately. The compressed charge in the cylinder does not ignite all at once or instantaneously, as many assume, but it is the strata of gas nearest the plug which is ignited first. This in turn sets fire to consecutive layers of the charge until the entire mass is aflame. One may compare the combustion of gas in the gas-engine cylinder to the phenomena which obtains when a heavy object is thrown into a pool of still water. First a small circle is seen at the point where the object has passed into the water, this circle in turn inducing other and larger circles until the whole surface of the pool has been agitated from the one central point. The method of igniting the gas is very similar as the spark ignites the circle of gas immediately adjacent to the sparking point, and this circle in turn ignites- a little larger one concentric with it. The second circle of flame sets flre to more
112 Starting, Lighting and Ignition Systems
of the gas, and finally the entire contents of the combiistion cham- ber are burning.
While ordinarily combustion is sufficiently rapid with a single plug so that the proper explosion is obtained at moderate engine if the engine is working fast and the cylinders are of
Fig. 51. — Doulile Pole Spark Flag and Method of Applying It to Obtain Two Sparks In Cylinder.
large capacity, more power may be obtained by setting fire to the mixture at two different points instead of but one. This may be accomplished by using two sparking plugs in the cylinder instead of one, and experiments have shown that it is possible to gain from twenty-five to thirty per cent, in motor power at high .speed with two-spark plugs, because the combustion of the gas is accelerated by igniting the gas simultaneously in two places. To
Double Pole Spark Plugs 113
fit a double-spark system successfully, one of the plugs must be a double pole member to which the high-tension current is first delivered, while the other may be one of ordinary construction.
A typical double-pole plug is shown in section at Fig. 54, A. In this member two concentric electrodes are used, these being well insulated from each other. One of these is composed of the usual form passing through the center of the insulating bushing, while the other is a 'metal tube surrounding the tube of insulating material which is wound around the center wire. The current enters ifee-^lug through the terminal at the top in the usual manner, but it does nol^ go to the ground because the sparking points are insulated from the steel body of the plug which screws into the cylinder. After the current ias jumped the gap be- tween the sparking head and the point, it flows back to the ter- minal plate at the top, from which it is conducted to the insulated terminal of the usual type plug.
Themelhod of wirii^ these plugs is shown at Fig. 54, B. The secondary wire from the coil or magneto is attached to the central terminal of the double-pole plug, and another cable is attached to the insulated terminal plate below it and to the terminal of the regular type plug. One is installed over the inlet valve, the other over the exhaust valve, if the system is fitted to a T head cylinder. Before the current can return to the source it must jump the gap between the points of the double-pole plug as well as those of the ordinary plug, which is grounded because it is screwed into the cylinder. "When a magneto of the high-tension type furnishes the current a double distributor is sometimes fitted, which will permit one to use two ordinary single-pole plugs instead of the unconventional double-pole member. Each of the plugs is joined to an individual distributor, and as but one primary contact breaker or timer is used to determine the time of sparking at both plugs, the ignition is properly synchronized and the sparks occur simultaneously.
Sometimes a spark plug of the special form shown at Fig. 53, C, is used in connection with a regular spark plug of the form shown at A, the special plug being placed first in the circuit and joined to the regular plug by a length of wire bridging the free termir
114 Starting J Lighting and Ignition Systems
of the plug at C with that on top of the insulator of the regular pattern. As the plugs are in series, the current must jump the gap of both plugs and thus two sparks occur, which is said to increase power by accelerating the rate of flame propagation* which of course results in more energeti^c ignition. The insulator is shaped to form a double V, the sides being slightly concave and
High Tension Wtrea Induction Coil—
Primarg Circuit
Dry Coils "^^ V-JJ^^^^"***^ Storage Battery
Fig. 55. — ^Assembly View of Four Cylinder Battery Ignition Group,
Showing Devices and Methods of Wiring.
#
larger than the center V, which ends in a sharp point. This con- struction is said to cause the point to be self-cleaning by the ex- plosion. Two electrodes pass through the insulating member in- stead of one, these being insulated from each other and the plug body as well. The high tension current enters one terminal and passes down one of the electrodes, jumps the air gap, and can only reach the ground if the terminal connected to the second electrode is in electrical connection with the terminal of an ordi-
Typical Battery Ignition System
115
nary form of spark plug or if it is bridged down to the plug body by the keeper B. When this keeper is in place, as indicated, the plug will act the same as a single electrode sparker. When the plug is to be used for double ignition in connection with one of the regular forms, the keeper B should be removed and a short
High Uneton WItea
Colt
Distributor
Storago Battery to Coit^^
Dry Cell Battery to Oolt^^
Tig. 56. — ^Method of Employing Single Vibrator Ooil to Fire Four Cylin- ders when Secondary Current is Distributed Instead of Battery Energy.
wire used to join the terminal to which the keeper was attached to the terminal of the regular pattern spark plug.
Typical Battery Ignition Systems. — The components of typi- cal battery ignition systems may be easily determined by studying the illustrations given at Figs. 55, 56 and 57. The four-cylinder ignition group shown at Pig. 55 depicts the conventional method of wiring two sets of batteries, a four-point timer or commutator^ and a four-unit induction coil together. It will be seen that eight dry cells are wired together in series and are used as an auxiliary
116 Starting, Lighting and Ignition Systems
to a six-volt or three-cell storage battery. The negative terminals of the storage battery and dry cell set are coupled together by a fihort length of wire and are grounded by being attached to the engine base by a suitable conductor. The positive terminals are coupled to the two binding posts under the switch or the coil. The four points of the commutator are attached to the different units of the coil while the secondary wires run from the high-
£
Switch
6 Side View
Con
Firing Order 1,2,3,6,5,4
P'^
Storage Battery
bry Cells
Hi!
^Qround"^
iiiJLjii
irV I
lijn
IHi
Cylinder Pair"
Fig. 57. — ^Distributor and Coil Ignition Group for Six GyUnder Motor, Showing Order of Firing and Wiring Connections.
tension terminals on the bottom of the coil to the spark plugs in the cylinders. If the switch lever is placed on one contact button, the current is obtained from the dry cells. If it is swung over to the other side, electricity from the storage battery is utilised! A typical high-tension distributor system is shown at Fig. 56. Two sources of primary current are provided, one being a six-cell, dry battery, the other a three-cell, or six-volt storage battery. The battery connections are similar to those previously shown and '^ut a single unit coil is needed to fire all cylinders. A single
Battery Igmtion Systems 117
primary wire is attached to the commutator section of the dis- tributor. The secondary wire from the induction coil is joined to tlie distributing terminal on the top of the distributor, from which it is delivered to the collecting terminals spaced on quar- ters around the outer periphery of the distributor casing by means
Fig. B8. — Complete Ford Uagneto Ignition System, & DisUnctlve M«tIiod
Found Only on This Cai.
of a central distributing segment. Suitable conductors connect the distributor with the spark plugs in the cylinders.
The illustration at Fig. 57 is practically the same as that at Fig. 56, except that a distributor capable of firing a six-cylinder engine is used. If individual unit coils were to be employed, as is the ease at Fig. 55, the coil box would contain six units and the
118 Starting, Lighting and Ignition Systems
primary timer would have six contact points. The wiring would be considerably more complicated than the system outlined.
Master Vibrator Ignition Systems. — Practically the only car at the present time using the individual unit system of ignition is the Ford, the complete wiring diagram of which is clearly shown at Fig. 58, in the relation the parts actually occupy in the car. It will be observed that the induction coil has ten terminals, six of these being for the primary circuit and four for the secondary wires. The upper terminals of the coil are primary and run to the timer segments. The four secondary terminals are connected to the spark plugs as indicated, while the remaining two terminals, which are at the bottom of the coil, are joined to the magneto terminal and to the battery respectively. In the system outlined each coil has a separate vibrator.
Many Ford cars have been supplied with what is known as a master vibrator, which is a magnetic circuit breaker intended to perform that function for all of the coils. It is claimed that a de- vice of this character produces synchronism of the ignition spark, which is not possible to obtain where four separate vibrators are used on account of some of these being tuned up faster than the others. It is contended that this makes a smoother-running engine and one delivering more power. A master vibrator unit that en- joys wide sale is of K-W manufacture and is designed especially for use with Ford cars. The method of wiring the vibi*ator is clearly outlined in the upper left hand corner at Fig. 59. As the vibra- tor unit carries a switch on its face, it has three terminals at the bottom, the center one of which is connected to one of the regular terminals of the spark coil, leaving the other one blank. One of the outside terminals of the master vibrator is coupled to the mag- neto, the other to a battery. The switcl; of the main coil is used only on one contact button, and may be left on that button, as the battery or magneto may be thrown in circuit at will by the switch on the master vibrator coil. It is necessary to short circuit the regular vibrators in order to put them out of commission. This is done by running a wire between the vibrator springs and the bridge carrying one of the contact points, as shown at the bottom of Fig. 59. Another method of short circuiting the vibrator is to
Master Vibrator Ignition Systems
110
keep the points in contact by wedging a piece of wood, rubber or cardboard under the vibrator spring between the core of the coil and the vibrator. Keeping the points in contact in this manner is equivalent to short circuiting them by the wire Bhunt.
When but one vibrator is used the contact points must be made larger than those on the individual vibrators, because it-does four times as much work. The construction of the K-W vibrator is
Bhowliw, boB to BhoR Oinult SftA Ooll TlbntDn
Fig. 59. — Bow Uast«r Vibratoi Is Used.
clearly shown, and in view of the instructions that will be given for the care and adjustment of these devices it is not neces- sary to describe its construction. The instructions given for adjusting the vibrator are very simple, it being merely neces- sary to observe if there is a apace of %4 inch between the plat- inum contact points when the vibrator spring is held down firmly on the iron core. A gauge made of ^4 inch thick steel may be placed between the contact points until the adjusting screw ia ■crewed down to a point where the gai^e can be pulled out with-
120 Starting, Lighting and Ignition Systems
out much trouble. This will give the proper distance for the arma- ture or bottom spring to travel.
Non-vibrator Distributor Systems. — Because of the almost uni- versal employment of electricity for lighting and starting systems, the battery ignition system has been improved materially inasmuch as the storage battery supplying the current is constantly charged by a generator. A number of systems has been devised, these operating on two different principles, the open circuit, such as the Atwater-Kent, previously described, and the closed circuit. An example of the close circuit system is shown at C, Fig. 60, and is of Connecticut design, the complete ignition system consisting of a combined timer and high tension distributor, a separate in- duction coil and a switch. The system is distinctive in that the timer is so constructed that the primary circuit of the coil is permitted to become thoroughly saturated with electricity before the points separate, with a result that a spark of maximum in- tensity is produced. The action is very much the same as that of a magneto on account of the saturation of the winding. An- other feature is the incorporation with the switch of a thermo- statically operated electro-magnetic device which automatically breaks the connection between the battery and the coil should the switch be left on with the motor idle.
Tlie contact breaker mechanism consists of an arm A carrying one contact, a stationary block B carrying the other contact, a fiber roller R which is carried by the arm A and operated by points on the cam C, which is mounted on the driving shaft. Normally the contacts are held together under the action of a light spring. As the four cams, which in touching the roller R raise the arm and separate the contacts, are 90 degrees for a four-cylinder motor, the period of saturation of the coil or the length of time the cur- rent flows through it to the battery is sufficiently long so that when the points have separated the current which has '* piled *' up induces an intensely hot spark at the plugs. This is an ad- vantage inasmuch as it insures prompt starting and regular ignition at low engine speed as well as providing positive ignition at high engine speed.
The thermostatic circuit breaking mechanism is very simple.
Battery Ignition Systems
122 Starting, Lighting and Ignition Systems
This consists of the thermostat T, which heats when the current passes through it for from thirty seconds to four minutes without interruption, and thus is bent downward, making contact with the contact L. This completes an electrical circuit which energizes the magnets M, causing the arm K to operate like the clapper in an electric bell. This arm strikes against the plate, which releases whichever of the two buttons in the switch may be depressed.
As will be observed, the transformer coil provided has five terminals. One of these is connected directly with the ground, the other leac*^ to the central secondary distributing brush of the timer-distributor. Of the three primary leads, one goes to the switch, one to the wire leading from the storage battery to the timer, and one directly to a terminal on the timer. The switch is provided with three buttons, the one marked B being depressed to start the engine, as the ignition current is then drawn from the storage battery. After the engine has been started the button marked M is pressed in, this taking the current directly from the generator. To interrupt ignition the button **off'' is pressed in, this releasing whichever of the buttons, B or M, is depressed. Four wires run from the distributor section of the igniter to the spark plug.
The 1916 Connecticut automatic ignition system, shown at Fig. Gl, is considerably simplified and more compact than earlier types. The igniter housing now has a rounded top for the reception of the leads to the spark plugs, this form being an improvement over the flat top in that it provides no lodging place for moisture and dust, etc. At the same time, the housing which carries the dis- tributor segments has been made lighter. The distributor arm also has been lightened and made more compact. Other improve- ments include the adoption of a new type of compression lock washer holding the cover plate over the breaker mechanism in place, and a new type of inclosed ball bearing at the lower end of the driving shaft. In principle, the new type of switch, which is in addition to the standard round type, is exactly like the older one except that it is mounted entirely behind the dash with noth- ing in view except a plate and four switch buttons. One of these serves to make the ignition circuit and another to break it. A
Battery Ignition Systems 123
third button switches on head and tail lamp and the fourth button dims the head lamps for city driving. Any combination of light- ing switches can be incorporated in the switch plate.
TMtBVfOSTAT
Fig. 61, — ^ninstnttloiis Sbowlng Conatructlou of 1916 Connecticut Ignition Systein Timers and TbeimostaticBlly Contrtdled Swltcli.
When the ignition switch is closed, current drawn from the storage battery is caused to pass through a tiny thermostat on its way to the coil and thence to the distributor, and finally to the
124 Starting, Lighting and Ignition Systems
plugs. If the motor is not started within a short time after the switch is closed — the length of time is easily adjustable — the ther- mostat closes a circuit through a tiny electric buzzer operating a releasing hammer which automatically opens the ignition circuit and thus prevents the battery draining itself. Obviously, if the motor is stalled and not again started, the thermostat will open the circuit in the same way. Thus, it is impos- sible for the motor to stand idle for more than a minute or so with the ignition switch closed. When the motor is run- ning the amount of cur- rent passing through the thermostat is so small that it is negligi- ble and has no effect.
The Remy system also operates on the closed circuit principle and is
Tig. 62.-EMily IgnlUon Unit Designed to Fit ^f""™ «* -*-■ ^'g- ^^' '" * Standard Magneto Base. form adapted for six-
cylinder engine igni- tion. The transformer coil is of the three terminal type, one secondary going to the central secondary distributing brush of the timer while one primary is joined to the primary contact terminal of the timer portion of the igniter. The remaining coil terminal is joined to the switch. One of the poles of the storage battery and one of the series connected dry cell batteries are grounded, while from the other two the wires run to the switch contacts. The current may thus be derived either from the dry cell batteries for emergency or from the storage battery for regular ignition purposes. The construction of the timer which incor- porates the breaker mechanism is clearly shown. The movable platinum contact point is carried by the arm A, which fulcrums on the bearing S, and which has a piece of hard steel F riveted
Battery Ignition Systems 125
to it to act as a cam rider. The earn C is of hexagonal form, having six points which separate the contacts when they ride over the shoe F attached to the arm A. The fixed platinum con- tact point B is so arranged that it may be adjusted by moving in or out as conditions demand. It is to this member that the primary terminal of the coil is connected.
A typical combined timer distributor known as the Halladay is shown at B, Fig. 60, The make and break mechanism is very
simple in design, as is the distributing mechanism. The contact between the platinum points is established by a four point cam. The secondary current is distributed from the central terminal to the four distributing terminals by a carbon brush very- mueh simi- lar in design to that employed in a high tension magneto. This operates on the open circuit principle. A complete ignition unit consisting of induction coil and timer-distributor of Remy design, so mounted that it will fit the standard magneto base and arranged so it can be driven in the same manner, is shown at Fig. 62. The wiring diagram of this igniter is outlined at Fig. 63. The indue-
126 Starting, Lighting and Ignition Systems
tion coil and eonstruetioii of distributor for six-cylinder engine igni- tion are depicted at Pig, 64. The Remy ignition system is some- times incorporated in a combined ignition-generator, as shown in wiring diagram at Fig. 65.
Features of Low-Tension Ignition STStem. — Though the low- tension ignition system is seldom used at the present time, a brief description of the method of producing a make-and-break spark is desirable so the reader may gain a thorough knowledge of the
Fig, 64.— Extenul View of R«mr Induction Coll at Iieft and Farta of TIiii«r-DIstiitmti»r at Bight.
methods of ignition in vogue. In order to obtain a spark in the cylinder of any engine, it is necessary that there be a break in the circuit and that this break or interruption be inside of the combustion chamber. The ^iter plate used is different in con- struction from the spark plug forming part of the high-tension system, as the break is made by moving contacts which serve to time the spark as well as produce it.
A typical igniter is shown at A and B, Fig. 66. It consists of
Low Tension Ignition System
127
a drop-forged plate approximately triangular in form which has a conical ground surface to fit a corresponding female member in the combustion chamber. It is secured by three bolts to a corner of the cylinder close to the inlet valve so the contact points will be traversed by the gases entering from the carburetor. As shown at B, the fixed contact point is called the anvil, while the movable
~VNAr-
jTMAcr aMTmnr
O^
MiTwi swrrcH
Fig. 65. — ^Wiring Diagram Showiiig Method of Connecting Bemy Ignition
Generator in Frimaxy Circuit.
or rocking member is called the hammer. The anvil is insulated from the igniter plate by a bushing of mica or lava, and the hammer alternately makes and breaks contact with the anvil.
The method of actuating the hammer by a rocker arm is clearly shown at ^ig. 67, B. The rocker arm H is in the form of a short lever ending in a slotted opening which is connected to the top of the vertical lifter rod T. This is actuated by a cam on. the inlet valve cam shaft C, which raises the plunger in the guide
128 Starting, Lighting and Ignition Systems
bushing. When the lifter rod movea upward the contact point on the hammer inside of the cylinder comes into contact with the platinum point on the anvil and closes the circuit. When the igniter cam reaches the proper point for igniting the charge the lifter rod T falls and as the action is quickened by a spring, S, 1, at the hottom of the lifter rod the ham- mer arm is separated from the contact point on the anvil and a spark takes place as the points are pulled apart.
The coil used when batteries are em- ployed to furnish the current is a simple form. It is a wind- ing of comparatively coarse wire around a core composed of a bundle of soft iron wire. The battery current is intensified to ft certain extent' by the self-induction of one layer of wire upon the others, and when contact is brok- en a brilliant spark occurs between the points of the igniter plate. Batteries are seldom used for regular service ,on the low-tension system because the demands are too severe. One of the advantages of this system is that the wiring is ex- tremely simple, as will be seen by consiilting the diagram of the low-tension ignition system illustrated at Fig. 67, A. In this both a low-tension magneto and set of batteries are provided, the former
rig. 66. — Coustructlon of Iiocomo^ile IiOw TeuBloa Ignltei Plate.
LiOW Tension Ignition System
129
being used for regular ignition while the latter are carried for emergency service. A simple form of magneto will serve any num- ber of cylinders because the insulated terminals of the igniters are joined together by a simple conductor or bus bar. *A wire from the magneto terminal is joined to one side of the switch, while the other side of the switch is coupled to the coil which is carried in
r
Fig. 67. — ^Diagram Showing Method of Operating Locomobile Low Tension
Igniter.
the battery box. A short wire connects the top of the switch lever with the bus bar. If the switch lever is swung to the left, the magneto produces the current for the igniters, and if the switch lever is placed on the button at the right, the current, supply is taken from the batteries. The dry cells are joined together in series connection, one pole being joined to a coil ter- minal, the other being grounded. The coil and the igniter plates are in series with the batteries and the current is returned to the
130 Starting, Lighting and Ignition Systems
ground through the rocker arm, which is a metallic contact with the igniter plate.
The disadvantage which has militated against the general use of the make-and-bVeak system of ignition is that it is very difficult to obtain synchronized spark after the mechanism has become worn, and unless the igniter plates are kept in perfect adjustment the spark time will vary and the efficiency of the engine will be lowered. As the moving electrodes operate under extremely disad- vantageous conditions it is difficult to prevent rapid wear of the rocker arm bearing at the igniter plate and consequent leakage of gas results. Owing to the multiplicity of joints in the operating mechanism it is difficult to secure regular action without backlash or lost motion.
With a high-tension system there are no moving parts inside of the cylinder and it is not difficult to maintain a tight joint between the plug body and the cylinder head. The timer mechanism which is employed when batteries and coils are utilized to furnish the cur- rent is a comparatively simple device which is not liable to wear be- cause it can be easily oiled and has a regular rotating movement which can operate without getting out of time much better than the reciprocating parts of the make-and-break mechanism. When a direct high-tension magneto is used the system is not much more ' complicated as far as wiring is concerned than a low-tension group, and as the ignition is more reliable it is not strange that jump spark or high-tension ignition is almost generally used in automo- bile practice.
Double and Triple Ignition Methods. — There are many cars in operation to-day which utilize double and triple ignition sys- tems. On some of these it is possible to have three practically in- dependent means of supplying the ignition spark. As will be ap- parent, the wiring of a triple ignition system is apt to be much more complex than that of the simpler methods now in vogue. In the ignition system outlined at Fig. 68, which has been used on a six cylinder car, it will be evident that in addition to the usual Bosch D-6 dual magneto an entirely independent individual spark coil and battery timer system is included. Two sets of plugs are used, one serving both magneto distributor systems, while the other
Double and Triple Ignition Systems 181
I
182 Starting, Lighting and Ignition Systems
Fig. 69. — ^wiring DUgrani of DonUe Ignition System at A, of Triple Ignition SfBtem At B, Botli for Foot Cylinder Englnee.
is connected to the individual coil units. The connections of the magneto system are no different than in the regular dual system previously described, while those of the battery and coil may be easily determined by a close study of the diagram. The primary timer has six contacts, one of which serves each ignition coil. As the firing order of this engine is 1-5-3-6-2-4, the wires from the timer must run to the individual unit coils in the same order so as to have the cylinders fire in proper sequence. For example, the wire from the contact No. 1 of the timer runs to coil No. 1,
Double and Triple Ignition Systems
133
next in order is contact No. 5, which is wired to coil unit No. 5. Following this comes timer contact No. 3, which supplies current to coil No. 3. While the individual spark coils are connected in order, i.e., coil No. 1 is joined to spark plug and cylinder No. 1, coil
7 4 3 2
MagajBto^
Switch
DryGelt Battery
.Storage Pattern
Fig. 70. — Practical Application of Double Ignition System to Four Cy^-
der Power Plant.
No. 2 to spark plug and cylinder No. 2, and so on the timer con- tact must be numbered according to the firing order. It will be apparent that two sources of ignition current are provided for the battery and coil systems, one being a storage battery, the other a set of dry cells.
184 Starting^ Lighting and Ignition Systems
A double ignition system in which a true high tension magneto is used and a four unit vibrator coil and four point timer is shown at A, Fig. 69. This ignition system is for a four-cylinder motor having a firing order of 1-3-4-2. At B, Fig, 69, a triple igni- tion system for a four-cylinder engine is shown, this being prac- tically the same as that outlined at Fig. 68 except that the wir- ing diagram is somewhat simpler owing to the lesser number of cylinders. The advantage of a double ignition system is that one can determine if irregular engine operation is due to the igni- tion system or not very easily by running the engine first on one system, then on the other. If the engine runs as it should on the battery system after it has been misfiring on the magneto it is reasonable to assume that some portion of the magneto system is not functioning properly. If the engine runs well on the magneto, but not on the battery, the trouble may be ascribed to failure in the chemical current producer or its auxiliary devices. On the other hand, if the engine does not run well on either ignition systems, it is fair to assume that the trouble is not due to faulty ignition. A non-technical illustration of one of the double igni- tion systems that were prominent before the general adoption of self-starters and when the high-tension magneto was not yet ac- cepted without suspicion is shown at Fig. 70.
Battery Ignition System Troubles. — Ignition troubles are usu- ally evidenced by irregular engine action. The motor will not run regularly nor will the explosions follow in even sequence. There may be one cylinder of a multiple cylinder motor that will not function at all, in which case the trouble is purely local, whereas if all the cylinders run irregularly there is some main condition outside of the engine itself that is causing the trouble. The first point to examine is the source of current. Full instructions for the care and repair of storage batteries are given in following pages so we will first consider the simple primary or dry cells. It will be observed that a dry cell is very simple in construction and that nothing is apt to occur that wiU reduce its capacity except diminu- tion in the strength of the electrolyte or eating away of the zinc can by chemical action. The elements in a dry cell are usually combined in such proportions that about the time the electrolyte
Battery Ignition System Troubles 135
is ezhausted, the zinc can will also have outlived its usefulness. It is much cheaper to replace dry cells with new ones than to attempt to repair the exhausted ones.
Evaporation of the electrolyte is the main cause of deteriora- tion of dry cells as the internal resistance of the cell increases when
Fig. 71. — View at A, Showing Internal Construction of Diy Cell Battery. B — Uethod of Testing Dry Cells wltlt Amperemeter.
the moisture evaporates. It is said that dry cells will depreciate even when not in use, so it is important for the repairman to buy these only as needed and not to keep a large stock on hand. In order to test the capacity of a dry cell an amperemeter is used as indicated at Fig. 71, B, Amperemeters are made in a variety of forms, some being combined with volt meters. The combination instrument is the best form for the repairman to use as the volts
186 Starting, Lighting and Ignition Systems
scale ean be employed for testing storage batteries -while the am- pere scale may be utilized in determining the strength of dry . cells, A fully charged, fresh dry ceU should show a current output of from twenty to twenty-five amperes. If the cell indi- cates below six or seven amperes, it should be discarded as it is apt to be exhausted to such a point that it will not furnish cur- rent enough to insure energetic or reliable ignition. Dry cells
Fig. 72. — Slurwlng Crastmctioii of Stotage Batterr Plates. Qilds at lAlt of UQatration are Not Filled wltli Actlro Material In Order to Oleuly SLOW Skeleton of Plate.
should always be stored in a cool and dry place, so that the elec- frolyte will not evaporate. If moisture is given an opportunity to collect on the top of the pitch seal it will allow a gradual loss of current due to short circuiting the cells. In applying an am- peremeter, care should be taken to always connect the positive terminal marked with a plus sign against the carbon terminal. In the indicating meter shown at B, it is necessary to use only one contact point which is pressed against the screw passing through the carbon rod. The case of the instrument is placed in contact
Storage Battery Troubles 137
with the zinc terminal to complete the circuit. A flexible wire is usually included in order to test the amperage of a group of cells should this be thought necessary. When dry cells are used for automobile ignition, they should be carefully packed in a box made of non-conducting material, such as wood, and securely cov- ered so there will be no chance for water to enter the container. If placed in a sheet metal case, care should be taken to line the box with insulating material and also to pack .the cells tightly so they cannot shake around. The best practice is to use wedges or blocks of wood which are driven in between the cells to keep them apart. In no case should a dry cell be placed directly in a steel box, as the binding posts on the zincs might come in contact with the walls of the box and tend to short circuit the cells, producing rapid depreciation. A battery box should always be placed at a point where it is not apt to be drenched with water when the car is washed or should be watertight if exposed.
Storage Battery Defects. — The subject of storage battery maintenance was thoroughly covered in a paper read by H. M. Beck before the S. A. E. and published in the transactions of the society. Some extracts from this are reproduced in connec- tion with notes made by the writer and with excerpts from in- struction books of battery manufacturers in order to enable the reader to secure a thorough grasp of this important subject with- out consulting a mass of literature. Endeavor has been made to simplify the technical points involved and to make the exposition as brief as possible without slighting any essential points. In view of the general adoption of motor starting and lighting sys- tems on all modern automobiles, the repairman or motorist must pay more attention to the electrical apparatus than formerly needed when the simple magneto ignition system was the only electrical part of the automobile. The storage battery is one of the most important parts of the modern electrical systems and all up-to-date repairmen must understand its maintenance and charging in order to care for cars of recent manufacture intelli- gently.
A storage battery, from an elementary standpoint, consists of two or more plates, positive and negative, insulated from each
138 Starting, Lighting and Ignition Systems
other and submerged in a jar of dilute sulphuric acid. The plates consist of finely divided lead, known as the active material, held in grids which serve both as supports and as conductors for the active material as at l^\g. 72. The active material being finely divided, offers an enormous surface to the eleetrolyt* and thus
Fig. 73.— Fait SecUonal View, Showing ConBtrnctioii of Exide Startlug and Lighting Battery.
electi-o-chemical action can take place easily and quickly. Tvro plat i such as described, would have no potential difference, the active material of each being the same. If, however, current from kin outside source is passed between them, one, the positive, will be- come oxidized, while the other remains as before, pure lead. This
Storage Battery Maintenance 189
combination will be found to have a potential diflferende of about two volts, and if connected through an external circuit, current will flow.
During discharge, the oxidized plate loses its oxygen and both plates will become sulphated until, if the discharge is carried far enough, both plates will again become chemically alike, the active material consisting of lead sulphate.. On again charging, the sulphate is driven out of both plates and the positive plate oxi- dized and this cycle can be repeated as often as desired until the plates are worn out. Thus charging and discharging simply re- sult in a chemical change in the active material and electrolyte, and the potential difference between the plates and capacity is due to this change.
In taking care of a storage battery, there are four points which are of the first importance:
First — The battery must be charged properly.
Second — The battery must not be overdischarged.
Third — Short circuits between the plates or from sediment under them, must be prevented.
Fourth — The plates must be kept covered with electrolyte and only water of the proper purity used for replacing evaporation.
In the event of electrical trouble which may be ascribed to weak source of current, first test the battery, using a low reading voltmeter. Small pocket voltmeters can be purchased for a few dollars and will be found , a great convenience. Cells may be tested individually and as a battery. The proper time to take a reading of a storage battery is immediately upon stopping or while the engine is running. A more definite determination can be made than after the battery has been idle for a few hours and has recuperated more or less. A single cell should register more than two volts when fully charged, and the approximate energy of a three-cell battery should be about 6.5 volts. If the voltage is below 6 volts the batteries should be recharged and the specific gravity of the electrolyte brought up to the required point. If the liquid is very low in the cell new electrolyte should be added. To make this fluid add about one part of chemically pure sul- phuric acid to about four parts of distilled water, and add more
140 Starting, Lighting and Ignition Systems
water or acid to obtain the required specific gravity, which is determined by a hydrometer. According to some authorities the hydrometer test should show the specific gravity of the electrolyte as about 1.208 or 25 degrees Baum6 when first prepared for in- troduction in the cell, and about 1.306 or 34 degrees Baum6 when the cell is charged.
The appended conversion formula and table of equivalents will be found of value in changing the reading of a hydrometer, or acidometer, from terms of specific gravity to the Baum6 scale,
or vice versa.
145
Sp. Gr. = at 60*' F.
145 — Baum6 degrees
The following table gives the corresponding specific gravities and Baume degrees:
|
BauTn6 |
Specific Gravity |
Baum6 |
Specific Gravity |
|
0 |
1.000 |
18 |
1.141 |
|
1 |
1.006 |
19 |
1.150 |
|
2 |
1.014 |
20 |
1.160 |
|
3 |
1.021 |
21 |
1.169 |
|
4 |
1.028 |
22 |
1.178 |
|
5 |
1.035 |
23 |
1.188 |
|
6 |
1.043 |
24 |
1.198 |
|
7 |
1.050 |
25 |
1.208 |
|
8 |
1.058 |
26 |
1.218 |
|
9 |
1.066 |
27 |
1.228 |
|
10 |
1.074 |
28 |
1.239 |
|
11 |
1.082 |
29 |
1.250 |
|
12 |
1.090 |
30 |
1.260 |
|
13 |
1.098 |
31 |
1.271 |
|
14 |
1.106 |
32 |
1.283 |
|
15 |
1.115 |
33 |
1.294 |
|
16 |
1.124 |
34 . |
1.306 |
|
17 |
1.132 |
35 |
1.318 |
Either voltage or gravity readings alone could be used, but ds both have advantages in certain cases, and disadvantages in others, it is advisable to use each for the purpose for which it
Charging Storage Batteries 141
is best fitted, the one serving as a check on the other. Voltage has the great disadvantage in that it is dependent upon the rate of current flowing. Open circuit readings are of no value, as'a cell reads almost the same discharged as it does charged. On the other hand, a voltmeter is a very easy instrument to read and may be located wherever desirable. Specific gravity readings are almost independent of the current flowing, but the hydrometer is diflScult to read, not very sensitive and the readings must be taken directly at the cells.
Charging the Storage Battery. — Great care should be used in charging and the charging rates given by the various manu- facturers should be followed whenever possible. It is essential that the positive wire carrying the charging current be connected with the positive plates of the battery. The positive pole of a cell is usually indicated by a plus sign or by the letter **P." In case of doubt always ascertain the proper polarity of the termi- nals before charging. This is done by immersing the ends in acidulated water, about an inch apart. The one around which the more bubbles collect is the negative, and should be connected with negative pole of the battery. If a cell is not connected prop- erly it will be ruined. A battery always should be charged, if possible, at a low charging rate, because it will overheat if ener- gized too rapidly. The normal temperature is between 70 and 90 degrees Fahrerlieit. When the battery is fully charged the solution assumes a milky white appearance and bubbles of gas are seen rising to the surface of the electrolyte. All foreign matter should be kept out of the batteries as any metallic substance find- ing its way into the cell or between the terminals will short circuit the cell and perhaps ruin it before its presence is known. The terminals, the outside of the cell and all connections, should be kept free from acid or moisture. A neglect of these essentials means corrosion and loss of capacity by leakage. There is one point in connection with the charge which should be especially emphasized, namely, that the final voltage corresponding to a full charge is not a fixed figure, but varies widely, depending upon the charging rate, the temperature, the strength of the electrolyte, and age of the battery. For this reason, charging to a fixed volt-
142 Starting, Lighting and Ignition Systems
Fig. 74. — ApplUmcBB for Charging and Testing Storage Batteries.
age is unreliable and likely to result disastrously. The charge should be continued until the voltage or gravity ceases rising, no matter what actual figures are reached. Old cells at high tempera-
Charging Storage Batteries'
143
tures may not go above 2.4 volts per cell, whereas if very cold, they have been known to run up to three volts.
The points to be especially emphasized in connection with the charge are:
First — On regular chaises keep the rates as low as practical and cut off the current promptly. It is preferable to cut off a
|
DISTILLED WATER |
AMPERE.MET |
R |
||
|
^ |
||||
|
JBER J6E B RECTIFIER ( |
=r |
3 |
||
|
S£^aa |
||||
|
^ |
\ |
|||
|
\/ |
^ BATTERY \ / |
|||
|
1 |
■^ |
r. |
||
Fig. 76.— Stand Sliown at A Facilitates Filling CeUs with DistiUed Water. Bectifler at B Cbarges Storage Batt«Ty from Alternating Cnrrent.
little too soon rather than to run too long where there is any question.
Second — Overcharges must be given at stated intervals and continued to a complete maximum. They should be cut off at the proper point, but when in doubt it is safer to run too long, rather than to cut off too soon.
Third — Do not limit the charge by fixed voltage.
144 Starting, Lighting and Ignition Systems
Fourth — Keep the temperature within safe limits.
Fifth — Keep naked flames away from cells while charging as the gas given off is inflammable. Always see that gas vents are clear before charging.
The following table will undoubtedly be of value as a guide to the proper charging rates of batteries of various ampere hour capacities, the assumption being that these are all 3 cell batteries that will show between 6.5 and 7.5 volts when fully charged. While most manufacturers of batteries furnish instruction books, these may be lost, so some compact reference is needed. The overall dimensions of the batteries are given so the capacity may be deter- mined even if the marks of identification on the name plate are obliterated
TABLE OF CHARGING RATES
Elba Lighting Batteries
|
Type. |
Normal Charging Rates. Amp. Required. |
24-Hr. Charg- ing Rate |
Volts per Cell at End of Charge at 24-Hr. Rate |
Volts of Battery at End of Charge at 24-Hr. Rate |
Size of Battery Over all |
No. |
|||
|
start |
Finish |
Length in in. |
Width in in. |
Height in m. |
of Cells |
||||
|
EI^— 60-00 |
9 |
8 |
3 |
2Ji |
H |
\m |
m |
9J4 |
3 |
|
ELB— 80-120 |
12 |
4 |
4 |
2J^ |
7H |
nH |
7H |
m |
3 |
|
ELB— 100-150 |
15 |
5 |
5 |
2}^ |
7y2 |
im |
7M |
OH |
3 |
|
ELB— 120-180 |
18 |
6 |
6 |
2J^ |
'TH |
\6% |
7H |
9H |
3 |
|
HSB— 60-90 |
9 |
3 |
3 |
2^ |
^Yl |
9% |
6 |
10 |
3 |
|
HSB— 80-120 |
12 |
4 |
4 |
m |
^Yl |
11 |
6 |
lOH |
3 |
|
HSB— 100-150 |
15 |
5 |
5 |
m |
7H |
12H |
6 |
lOH |
3 |
|
HSB— 120-180 |
18 |
6 |
6 |
2J^ |
7H |
15 |
6 |
lOJi |
3 |
|
PA B— 120-180 |
18 |
6 |
6 |
2^ |
7J^ |
w]4 |
73^ |
UH |
3 |
A battery may be charged from any source of direct current. Garages, central stations, lighting plants, etc., can do the work, vid in many instances where direct current is used for power
Storage Battery Restoration 145
purposes, a simple charging outfit is operated from the dynamo. Where alternating current only is available, a rectifier which changes alternating current to direct current may be installed and the battery charged with no inconvenience and at comparatively small cost. All of these methods will be considered in proper sequence and typical charging outfits described.
Remedies for Loss of Battery Capacity. — When a battery gives indication of lessened capacity it should be taken apart and the trouble located. If the cell is full of electrolyte it may be of too low specific gravity. The plates may be sulphated, due to lack of proper charge or too long discharge. The cells may need cleaning, a condition indicated by short capacity and a tendency to overheat when charging. Sometimes a deposit of sediment on the bottom of the cell will short circuit the plates. . If the specific gravity is low and the plates have a whitish appearance, there being little sediment in the cells, it is safe to assume that the plates are sulphated. Sediment should be removed from the cells and the plates rinsed in rain or distilled water to remove particles of dirt or other adhering matter.
The rate at which the sediment collects, depends largely upon the way a battery is handled and it is, therefore, necessary to determine this rate for each individual case. A cell should be cut out after say fifty charges, the depth of sediment measured and the rate so obtained, used to determine the time when the battery will need cleaning. As there is apt to be some variation in the amount of sediment in different cells, and as the sediment is thrown down more rapidly during the latter part of a period than at the beginning, it is always advisable to allow at least one- fourth inch clearance. If the ribs in the bottom of the jars are 1^ inches. high, figure on cleaning when the sediment reaches a depth of lJ/2 inches. Before dismantling a battery for ** washing,'' if practical, have it fully charged. Otherwise, if the plates are badly sulphated, they are likely to throw down considerable sedi- ment on the charge after the cleaning is completed
There have been many complaints of lack of capacity from batteries after washing. Almost without exception this is found to be due to lack of a complete charge following the cleaning.
146 Starting, Lighting and Ignition Systems
The plates are frequently in a sulphated condition when dis- mantled and in any case are exposed to the air during the clean- ing process, and thus lose more or less of their charge. When re-assembled, they consequently need a very complete charge, and in some cases the equivalent of the initial charge, and unless this charge is given, the cells will not show capacity and will soon give trouble again. This charge should be as complete as that de- scribed elsewhere in connection with the initial charge.
** Flushing 'V or replacing evaporation in cells with electrolyte instead of water, .is a most common mistake. The plates of a storage battery must always be kept covered with electrolyte, but the evaporation must be replaced with pure water only. There seems to be a more or less general tendency to confuse the elec- trolyte of a storage battery with that of a primary cell. The latter becomes weakened as, the cell discharges and eventually re- quires renewal. With the storage battery, however, this is not the cose, at least to anything like the same degree, and unless acid is actually lost through slopping or a broken jar, it should not be necessary to add anything but water to the cells between clean- ings. . Acid goes into the plates during discharge, but with proper charging it will all be driven out again so that there will be practi- cally no loss in the specific gravity readings, or at least one so slight that it does not require adjustment between cleanings. Thus, unless some of the electrolyte has actually been lost, if the specific gravity readings are low, it is an indication that some- thing is wrong, but the trouble is not that the readings are low, but that something is causing them to be low, and the proper thing to do is to remove the cause and not try to cover it up by doctor- ing the indicator. The acid is in the cells and if it does not show in the readings, it must be in the form of sulphate, and , the proper thing to do is* to remove the cause of the sulphation if there is one, and then with proper charging, drive the acid out of the plates and the specific gravity readings will then come back to the proper point. The too-frequent practice in such cases is to add electrolyte to the cells in order to bring up the readings, which as already explained, are only the indication of the trouble, and this further aggravates the condition, until finally the plates be-
Storage Battery Maintenance 147
come so sulphated that lack of capacity causes a complaint. This practice of adding electrolyte to cells instead of water, seems to be coming more and more common.
// there is any doubt about the polarity of the plates when re- assembling after cleaning it is well to note that the positive plate is chocolate in color and the negative is gray.
When plates are sulphated, to restore them to their original condition it is necessary that the battery be given a long, slow charge at about a quarter or a third of the normal charging rate. This should be continued until the electrolyte has reached the proper specific gravity and the voltage has attained its maximum.
It should be understood that sulphating is a normal as well as an abnormal process in the charge and discharge of storage batteries, and the difference is in the degree, not the process. The abnormal condition is that ordinarily referred to by the term. In normal service sulphating does not reach the point where it is difficult to reduce, but if carried too far, the condition becomes so complete that it is difficult to reduce, and injury results. A very crude method of illustrating the different degrees of sulphating is to consider it as beginning in individual particles uniformly dis- tributed throughout the active material. Each particle of sulphate is then entirely surrounded by active material. The sulphate itself is a non*conductor, but being surrounded by active material, the current can reach it from aU sides and it is easily reduced. This is normal sulphate. As the action goes further the particles of sulphate become larger and join together and their outside con- ducting surface is greatly reduced in comparison with their vol- ume so that it becomes increasingly difficult to reduce them and we have abnormal sulphate.
The general cure for sulphating is charging, so that a cell hav- ing been mechanically restored, the electrical restoration consists simply in the proper charging. Sulphate reduces slowly and on this account it is a good plan to use a rather low current rate. High rates cause excessive gassing, heating and do not hasten the process appreciably, so that it is the safer as well as the more efficient plan to go slowly. A good rate is about one-fifth normal. The length of charge will depend upon the degree of sulphating
148 Starting, Lighting and Ignition Systems
In one actual case it required three months' charging night and day to complete the operation, but this was, of course, an excep- tional one. ' The aim should be to continue until careful voltage and gravity readings show no further increase for at least ten hours and an absolute maximum has been reached. In serious cases it may be advisable to even exceed this time in order to make absolutely sure that all sulphate is reduced, and where there is any question it is much safer to charge too long, rather than to risk cutting off too soon. A partial charge is only a temporary expedient, the cell still being sulphated will drop behind again.
Battery Charging Apparatus. — The apparatus to be used in charging a storage battery depends upon the voltage and character of the current available for that purpose. Where direct current can be obtained the apparatus needed is very simple, consisting merely of some form of resistance device to regulate the amperage of the current allowed to flow through the battery. The internal resistance of a storage battery is very low and if it were coupled directly into a circuit without the interposition of additional re- sistance an excessive amount of current would flow through the battery and injure the plates. When an alternating current is used it is necessary to change this to a uni-directional flow before it can be passed through the battery. Alternating current is that which flows first in one direction and immediately afterward in the reverse direction. When used in charging storage batteries some form of rectifier is essential. The rectifier may be a simple form as shown at Fig. 74, A, which is intended to be coupled di- rectly into a lighting circuit by screwing the plug attached to the flexible cord in the lamp socket. A rotary converter set such as shown at B, may also be used, in this the alternating current is depended on to run an electric motor which drives the armature of a direct current dynamo. The current to charge the battery is taken from the dynamo, as it is suitable for the purpose, whereas that flowing through the motor cannot be used directly.
The view at Pig. 74, C, shows a usual form of hydrometer- syringe which is introduced into the vent hole of the storage bat- tery such as shown at E and enough electrolyte drawn out of the
to determine its specific gravity. This is shown on the hydrom-
Storage Battery Maintenance 149
eter scale as indicated in the enlarged section at D. A very useful appUance where considerable storage battery work is done is shown at Fig. 75, A. This is a stand of simple form designed to carry a carboy containing either acid, distilled water, or elec- trolyte. In fact, it might be desirable to have three of these stands, which are inexpensive, one for each of the liquids mentioned. In many repair shops the replenishing of storage batteries is done in a wasteful manner as the liquid is carried around in a bottle or old water pitcher and poured from that container into the battery, often without the use of a funnel. The chances of spilling are, of course, greater than if the liquids were carefully handled and more time than necessary is consumed in doing the work. The stand shown is about 5 feet high and is fitted with castors so it may be easily moved about the shop if necessary. For example, in taking care of electric vehicle batteries it may be easier to move the darboy to the battery than to remove the heavy battery from the auto- mobile. The container for the liquid is placed on top of the stand and the liquid is conveyed from it by a rubber tube. The rubber tube is attached to a glass tube extending down nearly to the bottom of the liquid. At the bottom of the rubber tube an ordi- nary chemist's clip which controls the flow of liquid is placed. In order to start a flow of liquid it is necessary to blow into a bent glass vent tube which is also inserted into the stopper. Once the rubber tube has become filled with liquid merely opening the clip will allow the liquid to flow into the battery as desired.
In most communities the incandescent lighting circuit is used for charging batteries on account of the voltage of the power circuits being too high. The incandescent lighting circuit may be any one of six forms. A direct current of either 110 or 220 volts used over short distances, either 220 or 440 volts on three wire circuits over long distances, alternating current at a constant potential, usually 110 volts and in various polyphase systems. It might be stated that in the majority of instances house and garage lighting circuits furnish direct current of 110 volts. We will con- sider the devices used with the alternating form, one of which is shown at Fig. 75, B. This is known as the RoUinson electrolytic rectifier which is based upon the following principles: When an
150 Starting^ Lighting and Ignition Systems
element of aluminum and a corresponding element or plate of iron are submerged in a solution of certain salts, using these elements as negative and positive terminals, respectively, the passage of an electric current through the solution produces a chemical action which forms hydroxide of aluminum. A film of hydroxide thus formed on the aluminum element repels the current. The arrange- ment of the cell will then permit current to pass through it in one direction only, the film of chemical preventing it from passing in the opposite direction. The result is that if an alternating cur- rent is supplied to the cell a direct pulsating current can be ob- tained from it. The outfits usually include a transformer for reducing the line voltage to the lower voltages needed for battery charging purposes. Regulation of the current is effected in the simplest type by immersing the elements more or less in the solu- tion in the jar. As complete instructions are furnished by the manufacturers it will not be necessary to consider this form of rectifier in detail.
One of the most commonly used rectifying means is the mercury arc bulb. This device is a large glass tube of peculiar shape, as shown at Figs. 76 and 77, which contains in the base a quantity of mercury. ' On either side of this lower portion two arms of the glass bulbs extend outwardly, these being formed at their extremities into graphite terminals or anodes indicated as A and A-1, Fig. 77, The current from the auto transformer is then attached one to each side. The base forms the cathode or mercury terminal for the negative wires. The theory of this action is somewhat complicated, but may be explained simply without going too much into detail. The interior of the tube is in a condition of partial vacuum and while the mercury is in a state of excitation a vapor is supplied. This condition can be kept up only as long as there is a current flowing toward the negative. If the direction of the current be reversed so that the formerly negative pole becomes a positive the current ceases to flow, as in order to pass in the opposite direc- tion it would require the formation of a new cathode element. Therefore the flow is always toward one electrode which is kept excited by it. A tube /)f this nature would cease to operate on «Hernating current voltage after half a cycle if some means were
Mercury Rectifier Bulbs
Pig. 76. — ^Mercniy Rectifier BulbB and Methods of Wiringi to Cbarge StOTUge Battery from Altem&tiiig Current Uain.
not provided to maintain a flow continuously toward the negative electrode. In the General Electric rectifier tube there are two anodes and one cathode. Each of the former is connected t© a separate side of the alternating current supply and also through reactances to one side of the load and the cathode to the other.
152 Starting, Lighting and Ignition Systems
As the current alternates, first one anode and then the other be- comes positive and there is a continuous flow toward the mercury- cathode thence through the load (in this case the battery to be charged) and back to the opposite side of the supply through a reactance. At each reversal the latter discharges, thus maintaining
H
k.OJ&TX
m
no or 2
Auto
tartiiTol^esidtapce
IfeotifierBiife
Balteiy
^i|i|i|i|i|iH
Fig. 77. — Simplified Wiring Diagram, Showing Method of Using Bectifier
Bulb.
the arc until the voltage reaches the value required to maintain the current against the counter E. M. F. and also reducing the fluctuations in the direct current. In this way, a true continuous flow is obtained with very small loss in transformation.
A small electrode connected to one side of the alternating cir- cuit is used for starting the arc. A slight tilting of the tube makes
Current Rectifying Devices 158
a mercury bridge between the terminal and draws an are as soon as the tube is turned to a vertical position. The ordinary form used for vehicle batteries has a maximum current capacity of 30 amperes for charging the lead plate type and a larger form in- tended for use with Edison batteries yields up to a limit of 50 amperes. Those for charging ignition batteries will pass 5 am- peres for one to charge six cells and a larger one that will pass 10 amperes for from three to ten batteries. As is true of the electro- lytic rectifier complete instructions are furnished by the manu- facturer for their use.
The "Wagner device, which is shown at Fig. 74, A, operates on a new principle and comprises a small two coil transformer to reduce the line voltage to a low figure ; the rectifier proper which consists of a vibrating armature in connection with an electro magnet and a resistance to limit the flow of the charging current. A meter is included as an integral part of the set for measuring the current flow. All sets are sold for use with ignition or light- ing batteries of low voltage with a lamp socket plug and attach- ing cord, the idea being to utilize an ordinary lighting circuit of 110 volts A, C. The magnet and vibrating armature accomplish the rectification of the current with little loss, the action after connection to the battery which is to be charged proceeding auto- matically. By a simple device, the current stoppage throws the main contacts open so the partially charged battery cannot be rapidly discharged. While the rectifiers are constructed to use 60 cycle, 110 volt alternating current they will work at all fre- quencies from 57 to 63. The size made will pass three to five amperes, the voltage being suflBcient to recharge a three cell battery.
When batteries are to be charged from a direct current it is possible to use a rheostat to regulate the voltage at the terminals. The construction of a rheostat is very simple as it consists only of a group of high resistance coils of wire mounted in insulating material and having suitable connections with segments on the base plate upon which is mounted the operating arm that makes the contact. According to the manner in which these are made and wired a large resistance is introduced at first, gradually de- creasing as the lever is moved over or it may operate in the re-
154 Starting, Lighting and Ignition Systems
verse fashion, a large amount of enrrent being allowed to pass at the first contact and less as the handle progresses across the path. Rheostats shonld only be purchased after consulting a ca- pable electrician as the required resistance must be figured out from the voltage of the circuit to be used, the maximum battery
Swttcli
To "DiMct" CacraatOnly
iiato2aoVoJu
Fig. 78. — ^How to Charge Storage Battery by Direct Current Tlirough
Simple Lamp Bank Besistance.
current, the charging rate in amperes and the number of cells to be charged at one time.
By far the simplest method of charging storage batteries is by interposing a lamp bank resistance instead of the rheostat. These are easily made by any garage mechanic and are very satis- factory for charging ignition or lighting batteries. Standard car- bon lamps of the voltage of the circuit shown should be used and the amperes needed for charging can be controlled by varying the candle power and the number of lamps used. If the lamps are to operate on 110 volt circuit, a 16 candle power carbon filament
Battery Charging Practice 155
lamp will permit one-half ampere to pass; a 32 candle power will allow 1 ampere to pass. If it is desired, therefore, to pass three am- peres through the battery, one could .use 3-32 candle power lamps, or 6-16 candle power lamps. If the lamps are to burn on 220 volts it should be remembered that when the voltage is doubled the amperage is cut in half, therefore the 32 candle power, 220 volt carbon filament bulbs will only pass half an ampere. The method of wiring is very simple as may be readily ascertained by re- ferring to Fig. 78. The line wires are attached to a fuse block and then to a double knife switch. The switch and fuse block are usually mounted on a panel of insulating material such as slate or marble. One of the wires, the positive of the circuit, runs from the switch directly to the positive terminal of the storage battery. The negative wire from the switch passes to the lamp bank resistance. The lamps are placed in parallel connection with respect to each other but in series connection in respect to the battery. When coupled in this manner the current must overcome the combined resistance of the storage battery which is very low and that of the lamps. This prevents the battery being charged with current of too high voltage.
A complete commercial installation which has been used suc- cessfully with a direct current of 110 volts pressure and which has a capacity for charging 30-6 volt batteries simultaneously is composed of two charging sets either of which may be employed independently or both may be used at the same time. The method of wiring is clearly shown at. Fig. 79. In this a three wire system is employed for lighting. This consists of one positive wire and two negative conductors, forming in reality two separate circuits so that one half of the installation is on one wire, while the re- mainder is on the other two. An upper branch is used merely for illumination. On either half of the three wire double circuit is placed a bank of lamps, these being in series with the batteries but the lamps are in multiple with each other. The board at the left has 9 sockets, that at the right 12 sockets. The number of lamps placed in these and their candle power regulate the amount of current in amperes that will pass through the battery. As we have seen, battery manufacturers advise that certain minimum and
156 Starting, lAghting and Ignition Systems
maximum charging rates be used. AssnTning that the maximum is 3 amperes, to pass a current of this value through the battery, it will be necessary to screw in 6-16 candle power lamps which will average 55 watts each, which means that at a pressure of 110 volts they require a current strength of half ampere. If fitted with 16 candle power lamps the 12 socket lamp bank will pass 6 amperes, and double this amount with lamps of twice the candle power.
Var Zlluainatioa-
XI
O
OMtfglnc Wbras
a" Wvm* Bloelc
r DDfeft
CO cc
Charging Wlr<M
Fig. 79. — ^Ziamp Bank Besistance for Charging a Number of Storage
Batteries Simultaneously.
The meter installation shown between the charging boards is to determine the amount of current passing through the storage bat- tery and as it is a low reading instrument, a low resistance shunt is interposed so that any overload will pass over the shunt instead of through the instrument which is calibrated to measure currents up to 30 amperes. With the small single blade knife switches in circuit the current will not pass through the instrument, as it is not advisable to include this in the circuit permanently, because the passage of current through the windings may result in in- jurious heating. To get a reading from either side the single blade
Features of Edison Cell 157
switch is thrown off and the double throw male member of switch is placed in contact between the blades on the side of which a reading is to be taken. It will be seen that tJie wires are crossed at the right of the two- way switch to cause the current to flow through the instru- ment in the right di- rection and also to have the negative ter- minal of each charging board at the left. This eliminates any con- fusion and the ter- minals are plainly marked so it is not possible to make a mis- take when coupling batteries. When more than one battery or set of cells is being charged they are wired in series, the negative terminal of one battery being coupled to the positive terminal of the neigh- boring one. In con- necting a battery to the charging board the negative wire should always be coupled to the negative terminal of the battery and the positive wire to the corresponding battery terminal.
Features of the Edison Cell. — The instructions given apply only to batteries of the lead plate type and not to the Edison bat-
Fig. 80. — Sectional Tlew of Edison Alkaline Storase Battery C«U.
158 Starting, Lighting and Ignition Systems
tery, which is entirely different in construction. The Edison cell, shown in section at Fig. 80, uses an electrolyte consisting of 21% solution of potash in distilled water so that the electrolyte is alka- line instead of acidulous. The positive plates consist of a series of perforated steel tubes which are heavily nickel-plated and which are filled with alternate layers of nickel hydroxide and pure metallic nickel in very thin plates. The tube is drawn from a perforated ribbon of steel, nickel-plated and has a spiral lapped seam. After being filled with active material it is reenforced with eight steel bands which prevent the tube expanding away from and breaking contact with its contents. The negative plate consists of a grid of cold rolled steel, also heavily nickel-plated, holding a number of rectangular pockets filled with powdered iron oxide. These pockets are also made up of finely perforated steel, nickel- plated. After the pockets are filled they are inserted in the grid and suDJected to considerable pressure between dies which corru- gate the surfaces of the pockets and forces them into positive con- tact with the grids. These elements are housed in a jar or con- tainer made from cold rolled steel which is thoroughly welded at the seams and heavily nickel-plated. The plates are assembled in positive and negative groups by means of threaded steel rods pass- ing through holes in one corner of the plates and insulating washers. The terminal post is secured to the middle of the rod. The complete element or plate assembly stands on hard rubber bridges on the bottom of the can as at Fig. 81 and is kept out of contact with the sides of the container by hard rubber spacers at- tached to the end. The can cover is also of sheet steel and contains fittings through which the electrodes pass, these being insulated from the cover by bushings of insulating material. A combined filling aperture ana vent plug is secured to the center of the cover plate. For 6 volt ignition and lighting service it is necessary to use 5 cells owing to the lesser voltage of the Edison batteries. The average voltage during discharge is but 1:2 volts per cell and is not as constant as is the case with a lead battery, the voltage of which may be as high as 2.5 volts per cell.
An Edison 6.5 volt battery (Fig. 81) used for lighting or igni- tion may be charged completely in ten hours. A feature of the
Features of Edison Cell
TiZf 81— Flate . Construction of Edison Cell and Method of Oiouplng Cells to Form Ugbtlng or Ignition Batterr-
160 Starting, lAghting and Ignition Systems
Edison battery is that overcharging at the normal rate has no harmful effects and it is advised by the maker to give the battery a 12 hour charge once every 60 days or when the electrolyte is re- plenished. The electrolyte must be kept sufficiently high so as to cover the plates and any loss by evaporation must be compensated for by the addition of distilled water. Another feature in which the Edison battery is superior to the lead plate type is that the plates will not.be injured if the cells are allowed to stand in a dis- charged condition. The external portions of the cells must be kept clean and dry because the container or can is made of a con- ducting material. The vent caps must be kept closed except when replacing electrolyte or bringing the level up to the proper height by adding distilled water. Care should be taken to avoid short circuiting of the battery by tools or metal objects and special em- phasis is laid on the precaution that no acid or electrolyte con- taining acid be poured into the cells. It is said that the Edison battery has a longer life than the lead plate type of equal capacity. While eminently suited for ignition and lighting, also for vehicle work, it is not as well adapted for starting purposes as the lead plate battery is.
Winter Care of Storage Batteries. — It would not da simply to leave the battery in the car for a period of, say, 4 or 5 months without giving it any care or attention, for in that case at the end of that time it would be found to have its plates so thickly covered with lead sulphate as to make it practically useless. For storage batteries '*to rest is to rust" and become ruined, unless special precautions are taken. Automobile storage batteries are all or nearly all of the sealed-in type from which the elements cannot be removed without a great deal of trouble. Therefore, the only method of keeping the plates intact consists in charging the battery at intervals of about two weeks. The following ad- vice concerning the care of batteries during a protracted period of idleness of the car is due to the Willard Storage Battery Co., and refers especially to the batteries of starting and lighting systems.
At intervals of 2 weeks the engine should be run until the electrolyte shows a specific gravity of 1.280. If this is done regu-
Winter Care of Storage Batteries 161
Jarly the engine need be run only about an hour each time. But if the owner should not be in possession of an hydrometer, it is better to run the engine for 2 or 3 hours each time, for the sake of safety. To charge the battery properly the engine should be run at a speed corresponding to a car speed of about 20 mph on the direct drive. There may be cases, however, where the owner is compelled to store his car in a space where it is practically im- possible to run the engine. Where this is the case, it is recom- mended, if electric current is available, that the owner purchase a rectifier or small charging machine. A charge over night, or for about 12 hours, every 2 weeks with this apparatus will be sufficient to keep the battery in a healthy condition. Before be- ginning the charging the battery should be inspected to see if it is filled with solution. If the solution needs replenishing, distilled water should be added until the solution fully covers the plates, which may be determined by removing the vent plugs and looking down into the cells. In case it is impossible to run the engine for charging and the owner does not care to incur the expense of purchasing a rectifier, he should remove the battery from the car and arrange for its storage at a garage which has charging facili- ties, stipulating that it must be charged every 2 weeks. The cost of having it so cared for will be nominal and will prove excellent insurance against deterioration.
To care for storage batteries of a type that is easily taken apart the following method is recommended: First charge the battery until every cell is in a state of complete charge. If there should be any short circuited cells they should be put into condition be- fore the charge is commenced, so that they will receive the full benefit of the charge. Then remove the elements from the jars, separating the positive from the negative groups, and place in water for about 1 hour to dissolve out any electrolyte adhering to the plates. Then withdraw the groups and allow them to drain and dry. The positives when dry are ready to be put away. If the negatives in drying become hot enough to steam, they should be rinsed or sprinkled again with clean water and then allowed to dry thoroughly. When dry, the negatives should be replaced in the electrolyte (of from 1.275 to 1.300 specific gravity), care
162 Starting, Lighting and Ignition Systems
being taken to immerse them completely and allow them to soak for 3 or 4 hours. Two groups may be placed in. a jar and the jar filled with electrolyte. After rinsing and drying the plates are ready to be put away.
The rubber separators should be rinsed in water. Wood sepa- rators after having been in service, will not stand much handling and had better be thrown away. If it is thought worth while to keep them they must be immersed in water or weak electrqlyte, (ind in reassembling the electrolyte must be put into the cells im- mediately, as wet wood separators must not stand exposed to the air for any unnecessary moment, especially when in contact with plates. Storage batteries always should be stored in a dry place, preferably in one where the temperature will never fall below 40° .Pahr, Storage battery solution or electrolyte varies greatly in density between the points of complete charge and complete dis- charge. "When completely discharged the electrolyte of the aver- age battery has a specific gravity of 1.14, and a sulphuric acid solution of 1.14 specific gravity has a freezing point of about 10° Fahr. Therefore, if a completely discharged battery is allowed to stand where it is exposed to extremely low temperature it is quite possible for the electroljrte to freeze and the cells to be injured in consequence. However, as already pointed out, a battery for other reasons must not be allowed to stand in the discharged condition for any length of time. With increasirg charge the density of the .electrolyte increases until, when the charge i? complete, it attains 1.28 specific gravity. The freezing temperature of the solution drops very quickly as the specific gravity increases, somewhat as follows :
Spec. Grav. Freez. Point Degrees
1.14 +10
1.16 + 5
1.175 — 4
1.20 —16
1.225 —36
1.25 —60
1.28 —85
Care and Repair of Spark Plugs 168
Consequently there is no possibility of a storage battery being injured by freezing in this latitude if it is kept in a fair state of charge.
Spark Plug Faults. — The part of the ignition system that is apt to give the most trouble, and for the most part through no fault of its own, is the spark plug which is placed in the combustion chamber in order to permit a spark to