Chapter XVII: Appendix (2)

In setting up a system of this description, the firing order of the engine must be ascertained, and this may be done by watching the order in which the exhaust valve stems move as the engine is slowly cranked. Piston No. 1 must then be brought to top dead center of the compression stroke, and about one thirty-second of an inch down on the power stroke, being stopped in this position. With the magneto screwed into place, the covers of the interruptor and distributor may be removed, and the armature revolved by hand in the direction in which it will be driven, until the interruptor opens, the spark control being in the most retarded position. A mark on the interruptor will come into line with a mark on the casing at the instant that the interruptor breaks contact. The magneto gear should then be meshed with the gear that drives it, and the lock nut set up.

The connection between the live end of the armature winding and the interruptor is arranged by the maker, but it is necessary to make connections between the magneto and the coil. A terminal will be found in the casing close to the stationary contact screw, and this is to be connected with one of the primary terminals of the coil, the other primary terminal either being grounded on the engine or the magneto, according to the construction. The moving part of the secondary distributor may then be connected with the secondary terminal of the coil. If the coil has but three terminals, two primary and one secondary, there are no further coil connections to be made, but if, as is sometimes the case, there are two secondary terminals, the free one is to be grounded on the engine.

An inspection of the distributor will show that the revolving part is beginning to make contact with one of the stationary points, and this point is to be connected to the spark plug of the cylinder in which the piston is at top dead center of the compression stroke. The next distributor point in the direction of rotation is to be connected with the spark plug of the next cylinder to fire, the remaining distributor points and spark plugs being connected in the order of firing.

Magnetos of this type are built to run in either clockwise or counter clockwise, and the two are not interchangeable. The direction in which the magneto is to be driven is indicated by an arrow stamped on the gear casing or end plate.

When the system is properly installed, the motor should start on a quarter-turn of the crank shaft, the crank being given a quick upward jerk. If it does not, the setting is incorrect, the connections are improperly made, or there is too great a distance between the points of the spark plugs. This distance should be one sixty-fourth of an inch.

CARE

The bearings of the armature and secondary shafts must be kept well lubricated, as well as the parts of the interruptor that require it.

Every few weeks, depending on the use, the carbon or steel brush bearing against the live end of the armature shaft must be wiped off with gasoline, and the same care must be given to the distributor contacts and to the platinum contacts of the interruptor.

When the platinum contacts of the interruptor become worn down after long use, or if for any other reason they require readjustment, they must be set so that the distance between them at the moment that the cam holds them apart is not more than one one-hundredth of an inch. This space may appear to be very small for the work that is to be performed, but it will be sufficient, and a greater distance will result in sparking that will burn down the contacts. In the Eisemann magneto, the adjustable contact is held by two nuts, and small open end wrenches are provided to fit. A wrench should be applied to each of these nuts, and the lower or lock nut loosened. This will free the upper nut by which the adjustment may be made, and the lock nut may then be tightened. The contact faces of the platinums should be kept flat and smooth, and true to each other, so that they come together squarely. If they are pitted after long use they may be faced off with a dead smooth file, but this is a job that requires great care, and must only be done under the most favorable conditions. When completely worn down they should be replaced with new ones.

TROUBLES

Should the engine show a tendency to miss, the first suspicion, if the magneto contacts are known to be correct, should fall on the spark plugs, and the easiest method of testing them out is to replace them with new ones. After considerable use, the spark plug points will burn off, and the size of the gap will increase to such an extent that the spark will find less resistance in traversing the safety spark gap than the gap in the plug.

In order that the ignition may be cut off for the purpose of stopping the engine, a switch is always provided by which the magneto may be short circuited, one pole of the switch being connected to the magneto terminal, or live wire, and the other pole grounded, as shown in Fig. 9. When this switch is closed, the magneto current flows through it in a closed circuit, and as it abandons its path through the interruptor there will be no further action in the coil, the ignition of course ceasing. This switch is often located in the rim or arm of the steering wheel, so arranged that pressing on a button closes the circuit and diverts the magneto current from the coil.

Any accidental short circuit of the magneto current will produce the same effect, and in case of the abrupt cessation of ignition, this is one of the probable causes. A short circuit in the secondary will usually make itself known by the snapping of the sparks as they pass through broken insulation or from a frayed cable end.

The remarks on general magneto troubles and care already made on page 254 also apply to a magneto of this type, and the same rules regarding the protecting of the circuit of the lines of the field must be borne in mind.

H.-T. MAGNETO SYSTEMS

A high-tension magneto differs from the types described in that the armature has a double winding; one, the primary winding, consisting of a few layers of coarse wire, and the secondary winding, placed over the primary, consisting of many layers of very fine wire. As the armature revolves, a current is induced in the primary winding, the circuit of which is kept closed until the armature reaches the position in which the induced current is at its greatest value. An interruptor operated by a cam then opens the primary circuit, and the sudden demagnetization of the armature core that results induces in the secondary winding a current of high pressure that is quite sufficient to jump the gap in the spark plug and to cause ignition of the mixture. The construction of the armature is more delicate than is the case with a low-tension magneto, for the secondary winding must have a large number of layers, and to permit this in the limited space, the wire must be fine. In addition, it must be insulated with the greatest care, for the intensity of the current produced will enable it to seek out and to break down any weakness that exists. There must also be two brushes, one for the primary current and one for the secondary, which complicates the construction.

A magneto of this type is shown in diagram in Fig. 10. In this case, the inner ends of both the primary and secondary windings are grounded, the live end of the primary being connected with the insulated contact of the interruptor, and the live end of the secondary leading to the rotating part of a secondary distributor. For the greater part of the revolution of the armature, the cam on the armature shaft permits the interruptor to maintain a closed circuit, but as the current reaches a maximum the cam breaks the circuit, and the flow of the primary current ceases. During this time, the secondary circuit has been open, the moving part of the distributor being out of contact with the stationary points. Under the law of induction, a current will only be induced in a closed circuit, and there is therefore no action in the secondary winding. When the primary current is at its maximum and its circuit is broken, another condition exists, for then the secondary distributor is making contact, the only gap being in the spark plug, but the sudden demagnetization of the armature core as the primary circuit is broken, and the additional effect as the armature passes the vertical position, induces in the secondary winding a current of great intensity that passes to the spark plug by way of the distributor, returning to the winding by the ground.

The parts of the interruptor are carried on one of the end plates of the magneto, and the secondary distributor revolves in bearings that support it under the arch of the magnets.

In the diagram shown provisions are made for a double ignition system, the operator having his choice of ignition by high-tension magneto direct or by battery, timer and coil. In practice, the three switches shown operate together. When magneto ignition is desired, the switch between the battery and ground is opened, and the switch at the secondary distributor thrown into contact with the point connected with the secondary terminal of the magneto. The third switch is thrown to make contact between the primary terminal of the magneto and the interruptor. If battery ignition is desired, the switch on the magneto primary is thrown to the point through which it is grounded, and the primary and secondary switches of the battery circuit closed. The upper contact points of the interruptor are then utilized to close primary circuit of battery, and the secondary current induced in coil is led to distributor. This complication of switches is necessary to prevent possibility of the battery current flowing through the armature winding, and to provide a short circuit for the primary of the magneto. If the engine is running on magneto ignition, it is stopped by throwing the primary switch to the point by which the primary is grounded. If running on battery, the circuit is broken in the usual way.

The current from a high-tension magneto is of such intensity that the small points of an ordinary spark plug would quickly be burned, and it is necessary to provide plugs with heavy points, which will stand the work. The distance between the points should be about one sixty-fourth of an inch.

The Bosch magnetos, which are perhaps in more general use than any other, are built on similar lines to the magneto just described, except that the grounded end of the secondary winding, instead of being attached to the metal of the armature, is connected to the live end of the primary winding, as shown in Fig. 11. The live end of the primary is brought out through a conducting rod passing lengthways through one end of the armature shaft, from which the current flows to the stationary contact of the interruptor. While in other magnetos the interruptor parts are stationary and operated by a moving cam, in this type the interruptor parts revolve with the armature, and the moving arm is operated by two fiber wheels as it drags around the inside of a stationary ring. By rotating the ring and the two wheels the interruptor is caused to operate sooner or later in its revolution, this giving the advance and retard of the spark.

The other end of the armature shaft carries the collecting ring for the secondary current, this consisting of a hard rubber disk around the surface of which is a metal ring to which the live end of the secondary winding is connected. A carbon brush is kept pressed against this metal ring by a light spring, and the current is thus led off to the revolving part of a secondary distributor.

The interruptor keeps the primary circuit closed until the current induced in the primary winding is at its maximum, when the opening of this circuit causes the rapid demagnetization of the core, and a powerful current is induced in the secondary, which flows to the spark plug with which the distributor is making contact.

A safety spark gap is applied between the brass strip that conducts the secondary current from the collecting brush to the distributor, and the metal of the magneto. The necessity for this device has already been explained, and it is essential that a magneto of this type should be so provided, because of the intensity of the current.

SETTING

In setting up a system of ignition with a magneto of this type, the firing order of the engine must be observed, and then one of the pistons brought to the point in the compression stroke that it will occupy when the spark is at the greatest advance. As has been explained in the case of engines equipped for the make and break system, this point will usually be from one-half to three-quarters of an inch before top dead center, the greater proportion of designs placing it at one-half an inch. The driving gear of a Bosch magneto is not keyed to the armature shaft, but shaft and gear are tapered, so that when the nut is drawn up tight there is no possibility of slipping. After the magneto is secured in position its gear may be meshed with the gear that is to drive it, but without drawing up the nut. The armature may then be turned by hand until it is in the vertical position, where it will be retained by the lines of force (Fig. 12), and the gear nut drawn up tight. If this position of the armature cannot be obtained by the sense of touch, it may be exposed to sight by the removal of the bridge that carries the safety spark gap, and of the dust cover that protects the space between the upper sides of the pole pieces.

The loosening of the three-armed frame on the front of the magneto will permit the removal of the covers of the interruptor and timer, and it will be seen that the moving part of the distributor is beginning to make contact with one of the stationary pieces; this should be connected to the spark plug of the cylinder that is in the firing position. The other contacts of the distributor should then be connected to the remaining spark plugs in the order of firing.

Ignition is cut out by short-circuiting the primary winding, and a binding post will be found on the front of the magneto under the three-pronged frame to which is connected the wire that leads to a switch making a ground connection when closed.

CARE

The armature and distributor shafts run on ball bearings, and these require the application of a few drops of oil twice a month. The interruptor is designed to operate without oil, and there is therefore little danger of oil working its way into the winding.

The carbon brushes must be wiped off with a little gasoline occasionally, and these are arranged in such a manner that they are easy of access.

The platinum contacts of the interruptor must be kept free from dirt and oil, and when, after long use, they become worn and uneven, they must be faced off by the use of a dead smooth file. The distance between them when separated by the action of the fiber rollers must not be more than one sixty-fourth of an inch, and this may be adjusted by means of the nuts. Accompanying each magneto is a small open end wrench for this purpose, to which is pivoted a leaf of steel that is to be used as a gauge for this distance.

This same measurement applies to the spark plugs, the points of which must provide a gap of not more than one sixty-fourth of an inch.

TROUBLES

If there is an abrupt failure of ignition, it is probable that the primary is short-circuited, and this can only occur on the wire that leads to the short-circuiting switch, for the other parts of the primary circuit are inclosed and protected against injury.

In case of the missing of one cylinder only, the trouble will usually be found in the plug, which may be short-circuited by a carbon deposit, or because the intense heat of the spark has fused the metal, resulting in the formation of a globule of metal between the spark points. Too great a distance between the points, more than one sixty-fourth of an inch, will prevent the passing of the spark, which will then be seen in the safety spark gap.

A miss in different cylinders may be due to defective insulation of the wires, but if these are in good condition the fault may be looked for in the magneto. The place where trouble is usually experienced is in the interruptor, which may become dirty, or the contacts may be worn down or loosened from the vibration. Fouled contacts in the distributor may also lead to a miss-fire, and this will be corrected by wiping the parts with gasoline. If all of these parts have been examined and found correct, it is inadvisable to examine further into the magneto, for inexperienced handling will be likely to injure the delicate parts. It is better to place it in the hands of a man whose shop is equipped for the work.

FOUR-SPARK MAGNETO

All of the magnetos described have been of the type in which the armature revolves, and two ignitions are secured per revolution. These are known as two-spark magnetos, or crank-shaft speed magnetos, from the fact that for four cylinder engines the magneto runs at the speed of the crank shaft. This is in distinction to the Bosch four-spark, or cam-shaft speed, magnetos, in which the armature as well as the field is stationary. This magneto for its simplicity, freedom from trouble, and workmanship, has few equals for the high-tension ignition of an internal combustion engine.

The armature in this magneto is of the usual type, and is stationary, with the armature neck in a vertical position. Around the armature, and between it and the pole pieces, revolves a soft iron shield in two sections, these being the length of the armature and the same width as the heads. As it revolves, it forms bridges between the pole pieces and the core of the armature, the lines of force flowing through it as well as through the armature. The diagrams of Fig. 13 show the positions of the shield as it revolves about the armature. In the first position, one segment of the shield forms a bridge between the pole piece and the upper armature head, while the other segment is bridging the space between the lower head and the other pole piece. When in this position, the lines of force flow through the neck of the armature and magnetize it so that it sets up its own field. When the shield revolves so that it covers the heads, the lines of force abandon the neck and flow between the pole pieces by the segments, the field established by the neck dying out. In the third position, the lines of force again flow through the neck, while in the fourth position, with the shield completing a half revolution, the lines of force again pass directly across. In this half revolution there are therefore two periods when a magnetic field forms around the armature neck and dies out, which will result in the induction of two currents in the winding of the armature. If the revolution is continued it will be seen that the same conditions are repeated, the positions of the two segments of the shield being reversed, and that one revolution of the shield about the armature will produce four waves of current in the winding. The magneto may therefore be driven at cam shaft speed for a four cylinder engine, and in addition has the advantage of the wire windings being stationary. The action of the magneto is the same as that of the two-spark type already described, but the construction is simplified because the slow speed of the shield will permit the secondary distributor to be attached directly to the armature shaft, the secondary shaft being done away with.

A diagram of the wiring is shown in Fig. 14. The primary wiring is grounded, and the live end brought out to the stationary contact point of the interruptor. The moving part of the interruptor is pivoted in the center, and the lower end, a polished steel knob, bears against the face of a disk that has four ribs running from center to edge. When the knob is on the space between two of the ribs, the interruptor closes the circuit, but as the disk revolves and a rib touches the knob, the arm moves on its pivot, and the circuit is broken.

The grounded end of the secondary winding is attached to the live end of the primary winding, and its other terminal passes to a contact point carried on a hard rubber disk placed on the revolving shaft immediately in front of the interruptor. The diagram shows a face view of this distributor, as well as a side view. A ring-shaped plate is set on one side of this disk, and is in connection with a contact piece carried on the edge of the disk. A carbon brush to which the live end of the secondary winding is attached is kept pressed against the ring-shaped plate, and the secondary current is thus led to the contact piece on the edge of the disk. As the disk revolves with the shaft of the shield the contact piece comes into successive contact with four carbon brushes, which are connected to the spark plugs.

When the shield is in such a position that the lines of force flow through the neck of the armature, the interruptor is closed, but when the intensity of the current increases to the maximum the interruptor opens, breaking the primary circuit, and producing a rapid demagnetization of the armature core. This dying out of the field induces a powerful current in the secondary winding, which is led by the distributor to one of the spark plugs, where it jumps the gap and returns to the winding by the ground connection.

SETTING

In setting the magneto the firing order of the engine is noted, as has been explained, and the magneto secured in position with its gear in mesh, but loose on the shaft. The cover over the space between the pole pieces will be found to be in the form of a shallow aluminum box, which is held in position by a single screw with a large head, and when this is removed the stationary armature and revolving shield will be exposed to view. One of the pistons must then be brought into the position it will take with a fully advanced spark, and the shield then revolved until it is in the position shown in Fig. 15. The nut securing the gear to the shaft may then be drawn up tight. It will be noticed that one of the segments of the shield has a deep notch at each edge. Remembering the direction in which the shield will be driven, the notch at the rear edge of the shield will indicate the position of the contact piece of the distributor which will then be coming into contact with the carbon brush of one of the stationary distributor contacts. The spark plug of the cylinder that is in the firing position should be connected to the brush that the notch indicates as making contact, and the remaining spark plugs and brushes connected according to the firing order.

CARE

The proper operation of the magneto requires the free and perfect action of the interruptor, and this may be observed by means of a brass slide that operates on the arm or the spark control lever. When this slide is raised, the action of the interruptor may be watched. Like the two-spark Bosch magneto, the distance between these points when the disk separates them should be one sixty-fourth of an inch, and contact should be made and broken without undue sparking. The condenser that will be found in the shallow aluminum box covering the space between the pole pieces prevents sparking at the interrupter, and is thrown into circuit automatically when it is placed in position.

The four-spark magneto is provided with a safety spark gap, and when the points of one of the spark plugs are separated too far, or when there is any interruption of the secondary circuit, a spark will show there. Sparks should not be permitted to pass in the safety gap for any considerable period, as damage will be done, and when they indicate by their presence that something is wrong, the trouble should be located and repaired without delay.

The regulation and care of the four-spark magneto is the same as has been described for the two-spark machine.

DUAL IGNITION SYSTEMS

It has been the custom to equip jump-spark engines with two complete systems of ignition, one operated by a magneto and the other by coil and battery. Each system has its own spark plugs, timing device, wiring, etc., the two being connected only at the switch. Many of these duplicate parts have been eliminated by the introduction of =dual ignition= systems, and the mechanism is correspondingly simplified. The Bosch dual system is a good example of the principles involved, and a diagram of the connections is shown on Fig. 16. The magneto used is of the usual two-spark type, except that the secondary current, instead of being led from the collecting ring direct to the distributer, is taken to the switch that is located in the coil box on the dash. In addition to the regulation interrupter illustrated on Fig. 11, the magneto is provided with a second interrupter or circuit breaker that controls the flow of the battery current, and takes the place of a timer. While the magneto interrupter revolves with the armature, and is operated by stationary cams, the battery circuit breaker is stationary, and is operated by a two-nose cam that revolves with the armature shaft. The stationary and revolving cams are so set that the interrupter and circuit breaker break their circuits at the same instant.

The coil is contained in a brass case on the dash, and in design and construction is a duplicate of the magneto armature. Attached to the coil is a handle that projects through a slot in the case, by means of which the coil may be turned partly around in the case. The terminals of the coil windings are attached to metal knobs located on the under side of a fiber plate that forms the bottom of the coil, and turning the coil by the handle moves these knobs in and out of contact with corresponding knobs on the bottom of the case. These knobs form the switch that cuts off all current, or permits the engine to be run on magneto or battery. When the switch is in such a position that the magneto produces secondary current, this flows from terminal 3 of the magneto to terminal 3 of the switch; thence by the switch connection to terminal 4 and to the secondary distributer. When the battery is switched in, the magneto primary is grounded, and secondary current from the coil flows over wire 4 to the secondary distributer.

By pressing a button on top of the coil case, a vibrator is cut into the circuit to permit starting the engine on the spark. When the engine starts the button is released, and ignition is produced by the single spark that results from the demagnetizing of the core that follows the breaking of the battery circuit by the circuit breaker. Throwing the switch breaks the battery circuit and cuts in the magneto.

INDUCTOR MAGNETOS

In types of magnetos that have recently been produced, the winding is stationary and surrounds a moving core that is magnetized and demagnetized during its revolution between the poles of the field magnets. The Remy magneto is of this type, and Fig. 17 is a diagram of the revolving core, or inductor, with the coil surrounding it. As the inductor revolves, the magnetism flows from one pole of the field magnets into the wing of the inductor nearest to it, through the central cylindrical part, and by the second wing to the other pole, the central part of the inductor then being magnetized. The magnetism of this portion dies away when the wings are in such a position that they bridge across from one pole to the other, but reappears when the central cylindrical part again becomes the only path by which the magnetism may flow. The constant changes in the magnetic strength of the central part affect the coil, and currents are induced in it. These currents, which are of low voltage, are led to the primary winding of a secondary induction coil similar to that used in the Eisemann system, the secondary current flowing to the plugs through a distributer located on the magneto. In the Remy system, the interrupter does not short circuit the magneto winding, as is the case with the Eisemann, but the flow of current is from the magneto winding to the grounded side of the interrupter, to the insulated screw, to the primary winding of the coil, and back to the magneto. The interrupter is closed and the current flows in this circuit while the strength of the current is increasing, but when the current is at a maximum the interrupter breaks the circuit, the core of the coil loses its magnetism, and a secondary current is induced. The current reaches a maximum twice in each revolution.

In other magnetos, the form of the inductor is such that six or more waves of current are produced during each revolution. An inductor of this type is shown in Fig. 18. There are six arms radiating from the central cylindrical portion, three at each end, and equally spaced. The coil is usually made of flat copper ribbon instead of wire, and it surrounds the central cylindrical part between the two sets of arms. In the inductor shown, the magnetism of the central part will change strength six times to each revolution.

Magnetos of this type are used to replace batteries in jump spark systems using vibrator coils. They are driven by belt, or by friction against the fly wheel, and are given a speed at least three times that of the crank shaft. By this means the waves of current follow one another at such brief intervals that the flow is practically continuous, and it is therefore unnecessary to time the magneto to the engine. These magnetos have no interrupters, and the wiring consists of one wire leading to the switch on the coil box, the usual connections between the coil box and timer, and a wire from the second magneto terminal to ground.

MAGNETIC MAKE-AND-BREAK SYSTEM

The flaming spark produced by the make-and-break system has many advantages for ignition over the jump spark produced by the high-tension system, but these are largely offset by the mechanical complication of cams, tappets, springs, etc. A make-and-break system in which the igniters are operated by magnetism has been perfected by the Bosch company, and is giving good results. The magneto used is of the ordinary low-tension type, equipped with an interrupter, while all of the igniter parts are contained in a plug that screws into the cylinder wall like a jump-spark plug. The plug is shown in diagram in Fig. 19. The sleeve that screws into the cylinder supports an iron core, the two being thoroughly insulated by blocks and washers of heat-proof insulating material. The upper portion of the core has a flat side, on which is formed a projection that serves as a pivot. A hammer bar is balanced on this pivot, its long end passing through the plug and coming into contact with an anvil attached to the screwed sleeve. A long horseshoe-shaped spring holds the two in light contact, and the hammer bar then forms the only path by which an electric current may pass from the core to the screwed sleeve and to the engine ground. When the hammer bar is moved on its pivot this connection is broken. Surrounding the core is a coil consisting of a few layers of wire covered with heat-proof insulation. The upper part of the plug is incased in a light iron casing screwed to the core, which completely incloses the core, hammer bar, spring and coil, and in which there is no opening that would permit the escape of compression from the combustion chamber. One terminal of the coil is connected to the binding post, and the other is grounded on the iron casing. The current generated in the magneto passes to a distributer and thence to the binding post of the plug, as shown in Fig. 20. It flows through the coil to the core, and thence by the hammer bar to the engine ground and back to the magneto. As the current establishes itself in the coil, the core becomes magnetized, and attracts to it the flat end of the hammer bar. When the hammer bar moves on its pivot, its connection with the anvil is broken, and this break in the circuit produces a flaming spark that is in every way identical with the spark of the ordinary mechanical make-and-break igniter. The casing that contains the coil may be unscrewed from the core without disturbing the screwed sleeve, and this makes it an easy matter to give the moving parts the inspection and cleaning that they should receive every few weeks. The spark occurs in the plug at the instant that the interrupter operates, and the setting up of the system is identical with that of the high-tension magneto systems.

A HANDY TESTING CHART*

WHAT TO DO WHEN THE ENGINE STOPS

Arranged for the Scientific American

(Copyright, 1909, by Munn & Co.)

EFFECTS OF TROUBLE

=Engine= { Test Ignition and
=will= { carbureter.
=not= { Slow cranking or cold weather will interfere with
=start.= { the proper formation or the mixture.
{ Prime cylinders with gasoline in cold weather
{ to obtain mixture for starting.
{ To increase suction in carbureter, prevent
{ operation of air-valve.

=Engine starts,= {
=but will not= { Fuel does not flow freely to carbureter.
=continue= { Weak battery.
=running.= {

=Explosions= { Break in ground wire, battery
=cease= { connections, switch lead.
=abruptly.= {

=Engine runs= { Worn timer.
=well slowly,= { Weak battery.
=but misses= { Faulty vibrator adjustment.
=when speeded= { Faulty carbureter adjustment.
=up.= { Fuel does not flow freely to carbureter.

=Engine will= { Preignition.
=not stop.= { Glowing carbon or metal point in cylinder.
{ Engine too hot (see Cooling trouble).

=Engine does= { Faulty setting of valves.
=not deliver= { Tight bearings or broken balls.
=full power.= { Indicated by excessive heating.
{ Back pressure.
{ Fouled muffler.
{ Dragging brakes.
{ Friction in transmission.
{ Faulty carburetion.
{ Weak ignition.
{ Weak compression.
{ Overheating.

{ Slipping timer.
{ Loose half-time shaft.
{ Sticking air-valve.
=Irregular= { Intermittent obstruction in spray nozzle.
=miss.= { Sticking valve.
{ Broken or weak valve-spring.
{ Loose connection.
{ Short circuit.

=Engine noises.= { Knocking.
{ Too much retard of spark.
{ Preignition.
{ Worn bearings.
{ Loose or cracked flywheel.
{ Hissing.
{ Broken piston rings.
{ Leaking air inlet pipe or gasket.
{ “Popping” in carbureter.
{ Leaking inlet valve.
{ Weak mixture.
{ Excessive retard of spark.

=Explosions= {
=weaken and= { Carbureter or fuel trouble.
=cease.= {

=Engine will= { Weak magneto.
=not run= { Faulty carbureter adjustment.
=slowly.= {

=Steady miss= {
=in one or more= {
=cylinders,= { Vibrator, timer, secondary circuit.
=(other= {
=cylinders= {
=firing= {
=normally).= {

=IGNITION.= { Test primary circuit
=Jump spark,= { as described for
=with single= { system using coils
=coil, battery= { and timer.
=secondary= { Secondary may
=distributor.= { short circuit from
{ Fouled or worn distributor.
{ Defective insulation.

=IGNITION.= { To test, revolve crank-shaft
=Jump spark,= { twice, listening
=with battery,= { for vibrators.
=timer and= {
=coils.= { =TEST 1. Alternate test,=
{ =prime cylinders with=
{ =a few drops of gasoline,=
{ =close relief cocks,=
{ =and crank.=
{ =Explosions show ignition=
{ =to be O. K.=
{ All vibrators sound normal, primary circuits
{ O. K. unless timer has slipped on shaft.
{ Vibrator should begin to operate as a piston
{ gets to top center of compression, with
{ spark lever retarded.
{ One or more vibrators }
{ sound normal, } To test coils, short
{ showing that } circuit the timer
{ battery connections, } by making contact
{ lead and } between primary
{ ground wires, and } terminal of
{ battery are O. K. } coil and ground.
{ Vibrator normal,
{ coil is O. K.,
{ look for
{ Interruption in timer circuit.
{ Blade moves, but
{ will not vibrate.
{ Punctured condenser ([1]).
{ Short circuit at vibrator.
{ Vibrator does not
{ operate.
{ Faulty adjustment.
{ Too stiff.
{ Will operate only with strong battery.
{ Excessive sparking at vibrator, and
{ battery exhausts rapidly.
{ Too weak.
{ Feeble secondary spark; misfiring with
{ slightly corroded contacts.
{ Contacts corroded.
{ Contacts stuck.
{ Vibrators do not operate.
{ Open switch; vibrator trouble.
{ Trouble in battery or in primary circuit.
{ To test, make momentary contact from switch
{ terminal to ground.
{ Bright spark, battery lead
{ and ground wire O. K.
{ Weak or no spark.
{ Break in battery connections,
{ lead or ground wire.
{ Battery exhausted or dry cells
{ polarized.
{ To test secondary, disconnect spark
{ plug leads, support them ⅜ inch from
{ engine ground and crank.
{ Good spark, O. K.
{ Weak spark.
{ No spark.
{ Vibrator trouble.
{ Plug short circuited, fouled, oily.
{ Points too far apart—should be 1/32 inch.
{ Short circuit in secondary.
{ Broken condenser connection ([1]).
{Shown by brilliant sparking at vibrator.

{ Explosions.
{ Ignition O.K. unless
=IGNITION.= { Magneto is out of time and igniters
{ incorrectly adjusted.
Make and break, } Should break circuit at top center
with low } of compression when spark is retarded.
tension magneto. { No explosions.
{ Short circuit.
Use Test 1, { Insulated bridge on magneto.
cranking { Switch or switch lead.
briskly. { Bus-bar or bus-bar lead.
{ Igniter insulator broken.
{ Igniter stuck closed.
{ Broken spring.
{ Tappet stuck in guide.
{ To test operate by hand.
{ Open circuit.
{ Magneto broken down.
{ To test magneto, disconnect magneto lead from
{ bus-bar and hold free end in bare fingers, or
{ =TEST 2. Hold free end against teeth=
{ =of metal gear and crank briskly.=
{ Shock or spark.
{ Magneto O. K.
{ No shock or spark.
{ Fouled collecting brush.
{ Armature burned out [1].
{ Fields demagnetized [1].
{ To test, unmesh gear, revolve armature
{ by hand. If fields are O. K.,
{ armature should turn perceptibly
{ hard twice in each revolution.

=CARBURETER.= {Mixture ignites.
{ Proving that carbureter is doing its duty.
To test, hold { Mixture does not ignite. Operate primer to flood
lighted match { float chamber.
over open relief { Gasoline drips from spray nozzle.
cocks while { Mixture too rich.
engine is { Insufficient air.
cranked briskly. { Faulty adjustment of air valve.
{ Clogged inlet pipe.
{ Dust on inlet pipe screen.
{ Leaking float valve.
{ Float too heavy.
{ Soggy (if of cork) ([2]).
{ Punctured (if of metal) ([3]).
{ Faulty adjustment of float.
{ Mixture too poor.
{ Too much air.
{ Water in gasoline.
{ Faulty adjustment of air-valve.
{ Leaks in inlet pipe.
{ Faulty adjustment of float.
{ No drip from spray nozzle.
{ Clogged spray nozzle.
{ Clogged float valve.
{ Clogged fuel feed.
{ No gasoline.
{ Empty tank.
{ Closed supply cock.

=IGNITION.= { Proceed as in Test 1, cranking briskly.
{ Explosions.
Jump spark with { Ignition O. K. unless magneto is out of time.
low tension { Should be reset.
magneto and coil { Sparks in safety spark gap.
(Eisemann, Remy, { Interruption in secondary circuit.
Splitdorf, etc.) { Too wide a gap at plugs (should be from 1/64
{ to 1/32 inch).
{ No explosions.
{ Primary circuit open.
{ Primary short circuit.
{ Magneto broken down.
{ To test magneto, disconnect primary lead
{ to coil and proceed as in test 2.
{ Shock (or spark), magneto O. K.
{ No shock (or spark).
{ Interrupter short circuited, wet
{ or oily.
{ Field demagnetized ([1]).
{ Condenser broken down (shown by
{ brilliant spark at interrupter) ([1]).
{ Coil broken down.
{ To test primary winding of coil disconnect
{ ground wire and proceed as in
{ second part of test 2.
{ Spark, winding O. K.
{ No spark.
{ Winding broken ([1]) down or short
{ or open circuited.
{ To test secondary winding of coil,
{ disconnect spark plug leads from magneto
{ and crank briskly, watching for sparks
{ at safety spark gap.
{ Sparks, look for
{ Plugs short circuited.
{ Fouled.
{ Insulation broken down.
{ Fused metal bead at points.
{ Secondary short circuit ([1]).
{ Leads short circuited.
{ Ground circuit open.
{ No sparks, winding broken down.

=IGNITION.= { Proceed as in Test 1, cranking briskly.
{ Explosions.
High tension { Ignition O. K. unless magneto is out of time.
magneto (Bosch, { Should be reset.
U. & H. Lacoste, { Sparks in safety spark gap.
Witherbee, etc.) { Break in secondary circuit.
{ Too wide a gap at plugs (should be from
{ 1/64 to 1/32 inch).
{ No explosions.
{ To test magneto, disconnect spark plug leads
{ from distributor and crank briskly,
{ watching for sparks at safety spark gap.
{ Sparks.
{ Magneto O. K.
{ Look for short circuits in
{ Spark plugs.
{ Fouled.
{ Insulation broken down.
{ Bead of fused metal between points.
{ Switch lead.
{ Switch.
{ No sparks.
{ Corroded interrupter contacts.
{ Interrupter stuck.
{ Armature burned out ([1]).
{ Condenser broken down ([1]).
{ Field demagnetized ([1]).

=FUEL FEED= { To test, open drain cock at carbureter.
=SYSTEM.= { Gasoline flows.
{ System is O. K.
{ Gasoline does not flow.
{ Gravity feed.
{ Clogged vent hole in filling cap.
{ Clogged piping ([4]).
{ Pressure feed.
{ Sufficient pressure in tank.
{ Clogged piping ([4]).
{ Insufficient pressure in tank.
{ Leaking tank or piping.
{ Leaking filling cap.
{ Stuck relief valve.

{ To test, crank engine slowly, noting resistance,
{ which should be the same in all cylinders.
=COMPRESSION.= { (Do not confuse constant mechanical
{ resistance with intermittent resistance of
{ compression).
{ Inject oil into faulty cylinder.
{ Improved compression indicates
{ Stuck piston rings.
{ Douse cylinder with kerosene and alcohol
{ ½ and ½ to cut carbon.
{ Worn or scored piston rings.
{ Scored cylinder walls.
{ No improvement in compression indicates
{ Worn or pitted valves.
{ Leaking spark plug, igniter plate,
{ relief cock, etc.
{ Test by running oil around these
{ and cranking.
{ Leak indicated by bubbles.
{ Piston ring splits in line.
{ Broken piston rings.
{ Crank case will be abnormally warm.
{ Cracked walls or head.
{ Indicated by water in cylinder.
{ Sticking valves.
{ Insufficient space between valve stem and
{ push rod.

{ Radiator should heat evenly shortly
=COOLING.= { after engine is started.
{ Radiator does not heat.
(Water.) { Clogged circulation system.
{ Empty tank.
{ Clogged piping.
{ Defective pump.
{ Test by opening pet cocks.
{ Radiator steams.
{ Failure of lubrication.
{ Indicated by groans from cylinders affected.
{ Supply should be just sufficient to
{ produce faint whiff of blue smoke
{ at exhaust.
{ Defect in circulation.
{ Too much running on retarded spark or on
{ low speed.
{ Slipping fan drive.

* It is taken for granted that the engine is capable of running properly, that the tanks are filled, and that the switch is correctly thrown.

[1] Return to makers for repair.

[2] Dry in oven, and coat with shellac.

[3] Plunge in hot water to expel gasoline and to locate leak. Repair with solder.

[4] May be cleared with blast from foot pump.

INDEX

Adjusting screw for vibrator, 103.

Advance of ignition, 13.

Advancing ignition by moving timer, 101.
too far, 13.

Air cooling, 34.
requisites for, 35.

Air inlet, auxiliary, adjustment of, 231.

Air intake trouble, 197.

Amperes, 77.

Antifreezing mixture, 200.

Antiskid devices, use of, 174.

Armature of generator, 88, 256.

Assembling springs, 229.

Automatic carburetor, 58.

Automatic valve, 25.
action of, 26.
adjustment of, 233.
spring of, 27.

Auxiliary air, necessity for, 56.

Auxiliary air inlet, action of, 57.
adjustment of, 231.

Axle, dead rear, 152.
live rear, 146.
necessity for fixed front, 162.
rear, floating, 148.
sprung, effect of, 148.

Back pressure, 18.

Backfiring, causes of, 218.

Balance of engines, 37.

Band brake, 167.

Battery, causes of trouble in, 182.
cross-connected, 182.
nearly exhausted, 183.
recuperation of, 183.
weak, effect of, 213.

Battery connections, 84.

Bearings, tight, effect of, 210.
tight, testing for, 221.

Bevel gears, necessity for, 142.

Bosch magnetos, 301, 308, 317, 323.

Brake, motor as, 170.

Brake equalizer, 172.

Brakes, 167.
emergency and running, 169.
tight, effect of, 210.
testing for, 221.

Broken wire, 181.

Bus bar, 204.

Cam, 26.
action of, 26.
parts of, 26.
worn, effect of, 235.

Cam shaft, 28.

Carbon deposit from burned oil, 31.

Carburetion, 52.

Carburetor, action of, 55.
adjustment of, 231.
automatic, 58.
cleaning of, 196.
dirt and water in, 195.
effect of varying speed on, 56.
float feed, 53.
flooding of, 195.
mechanically controlled, 58.
necessity for, 53.
necessity for auxiliary air in, 56.
parts of, 53.
principle of, 53.
surface, 64.
testing of, 207.
trouble in, causes of, 195.
types of, 58.
with central mixing chamber, 61.
with side mixing chamber, 60.

Carburetor adjustments, 58.

Chains, care of, 225.
cleaning and lubricating of, 225.
driving, adjusting of, 225.

Change speed mechanism, friction type of, 141.
individual clutch type of, 138.
necessity for, 119.
planetary type of, 132.
sliding gear type of, 120.

Changing gear, principle of, 125.

Charging of storage battery, 82.

Check and relief valves, 72.

Chemical generators, 80.

Circuit breaker, magneto, 286.

Circuit, jump spark system, 108.
primary, testing of, 206.
primary and secondary, 109.
parts of, 97.
secondary, testing of, 212.

Circulation, failures of, 199.

Circulation connections, troubles of, 199.

Circulation of water, forced and gravity, 32.

Classes of gasoline engines, 5.

Cleaning, use of kerosene for, 224.

Cleaning carburetor, 196.
chains, 225.
combustion space, 223.
crank case, 224.
differential, 224.
gear case, 224.
lubricator pipes, 202.
spark plug, 187.
tires, 222.

Clearance, 17.

Closing of exhaust valve, 17.
of inlet valve, 8.

Clutch, action of, 113.
friction cone, 113.
internal expanding, 118.

multiple disk, 114.
parts of, 116.
necessity for, 112.
reversed friction cone, 114.
slipping of, effect of, 210.
withdrawing of, when changing gear, 113.

Coil trouble, causes of, 186.

Coils, matching of, to cylinders, 230.
testing of, 206.

Cold, effect of, on starting engine, 209.

Combustion, pressure from, 4.

Combustion and explosion, 4.

Combustion space, 8.
carbonized, effect of, 215.
cleaning of, 223.

Commutator, 97.

Compensating gear (see Differential).

Compression, during exhaust stroke, 16.
effect of, 10.
on spark, 188.
necessity for, 10.

Compression leaks, 197.
testing for, 211.

Compression limit, 14.

Compression trouble, causes of, 197.

Compression-combustion stroke, 8.

Condenser, action of, 109.

Conductors and insulators, 76.

Cone clutch, friction, 113.

Connecting rod, 23.

Connections, battery, 84.
loose, effect of, 212, 213.
making, 180.
of secondary distributer, 111.

Construction of bevel gear differential, 153.
of primary induction coil, 93.
of secondary induction coil, 96.
of spark plug, 107.
of spur gear differential, 157.
of switch, 89.

Contracting brake, 167.

Control of steering, 164.

Coolers, 32.

Cooling, air, 34.
requisites for, 35.
failure in, effect of, 215.
water, 31.

Cooling cylinder, necessity for, 30.

Cooling system freezing, 200.

Cooling systems, 31.

Cooling trouble, causes of, 199.

Cooling water, flow of, 31.

Corrosion, effect of, 181.

Crank case, cleaning of, 224.
depth of oil in, 224.

Crank pin, 23.

Crank shaft, 20.
four-cylinder engine, 43.
180°-, effect of, 39.
360°-, effect of, 41.

Crank shaft points, 22.

Crank shaft throws, 38.

Cranks, relative positions of, 22.

Current, flow of, 75.
induced, 94.
secondary, 97.

Cycle, 4.
events of, 6.
strokes of, 6.

Cylinder, 25.
faulty, testing for, 212.
matching coils, to, 230.
necessity for cooling, 30.

Cylinder head, 5.

Defects of surface carburetors, 64.

Deposit from burned oil, 31.

Differential, bevel gear, construction of, 153.
cleaning of, 224.
location of, 158.
necessity for, 152.
operation of, 165.
spur gear, construction of, 157.

Direct drive, 124.

Disk, valve, 25.

Disk clutch, 114.

Distance rods, necessity for, 176.

Distributer, causes of trouble in, 192.
secondary, 110.

Double-acting brake, 167.

Double-chain drive, 150.

Double-opposed engine, 38.

Drag link, 162.
bent, effect of, 228.

Drive, double chain, 150.
driving shaft, 144.
final, 142.
propeller or driving shaft, 144.
single chain, 142.

Drives, advantages of different types of, 158.

Driving chains, adjusting of, 225.

Driving gear ratios, 159.

Dry cells, 80.
voltage of, 81.

Dynamo, action of, 88.

Eisemann system, 283 _et seq._

Electric current, generation of, by magnetism, 87, 254.
production of, 80.

Electrical measurements, 77.

Electrolyte, 82.

Electro-magnet, 87, 253.

Emergency brake, 169.

Engine, care of, 223.
distinction between two-cycle and four-cycle, 5.
effect of cold on starting, 209.
failure of, to deliver full power, 209.
to start, 208.
four-cycle, 5.
missing of, at high speed, 213.
parts of, 20.
starting, then stopping of, 214.
stopping of, 216.
timing of, 232.
two-cycle, 47.
two-cycle, action of, 49.
vibration of, 37.

Engine as a brake, 170.

Engine balance, 37.
four-cylinder, 41, 43.
H. D. O., 38.
three- and
six-cylinder, 44.
two-cylinder, 38.

Engine types, advantages and disadvantages of, 45.

Epicyclic gears (see Planetary).

Equalizer, brake, 172.

Events of cycle, 6.

Exhaust stroke, 16.
compression during, 16.

Exhaust valve, closing of, 17.
opening of, 15.

Expanding brake, 167.

Expanding clutch, 118.

Explosion and combustion, 4.

Explosions, missing, 211.
weak, 210.

Field, magnetic, 88, 251.
of generator, 88.

Final drive, 142.

Firing order, 44.

Float, punctured, 196.

Float and float chamber, carburetor, 53.

Float feed carburetor, 53.

Floating rear axle, 148.

Flow of cooling water, 31.
of current, 75.
of electricity, definition of, 79.

Fly wheel, necessity for, 8.
vibration absorbed by, 37.
weight of, 42.

Force circulation of water, 32.

Fouled spark plug, causes of, 187.

Four-cycle engine, 5.

Four-cylinder engine balance, 43.

Four-cylinder engine crank shaft, 43.

Four-cylinder engines, 43.

Freezing of water, 200.

Friction transmission, 141.

Gases, properties of, 1.

Gasoline, dirt and water in, 193.
separating water from, 193.
spraying, necessity for, 57.

Gasoline engine, action of, 4.
classes of, 5.
functions of (see Cycle).
not self-starting, 18.
power of, 18.
without reserve power, 19.

Gasoline feed pipe trouble, causes of, 195.

Gasoline feeds, gravity and pressure, 66.

Gasoline line, trap on, 73.

Gasoline strainer, 73.

Gasoline trouble, causes of, 193.

Gasoline vapor, 52.

Gear case, cleaning of, 224.

Gears, two-to-one, 28.

Generator field and armature, 88.

Generator terminals or poles, 75.

Generators of electric current, 81.

Governor-controlled carburetor, 62.

Gravity feed of gasoline, 66.

Gravity system of water cooling, 34.

Grinding valves, 226.

Grounding the return, 79.
the secondary circuit, 108.
the timer, 101.

Gudgeon pin (see Wrist Pin).

Half time shaft, 28.

Heat, 1.
excessive, result of, 30.
losses, 15.
produced through resistance, 77.

Horizontal double-opposed engine, 38.

Hydrometer, 83.

Igniter, 91, 268.
adjustment of, 276.
magnetic, 323.

Igniter bearing, 190.

Igniter contacts, 190.

Igniter points, setting, 189, 276.

Igniter tappet, 92.
spring of, strength of, 190.

Igniter trouble, causes of, 189.

Ignition, affected by improper mixture, 12.
affected by speed, 12.
necessity for, 8.
necessity for early, 11.
speed controlled by, 14.
too far advanced, 13.
too far retarded, 13.

Ignition advance, 13.

Ignition lead (see Necessity for Early Ignition).

Ignition retard, 13.

Ignition system, parts of, 75.
purpose of, 74.

Ignition systems, 91.

Ignition testing, 203.

Ignition timing, 192.

Ignition trouble, causes of, 179.

Ignition wiring, 236.

Imperfect combustion of mixture, 10.

Improper mixture, ignition affected by, 12.

Individual clutch, 138.

Induced current, 94, 254.

Induction and magnetism, 93, 254.

Inductor magnetos, 319.

Inflation of tires, 173.

Inlet pipe, 53.

Inlet stroke, 8.

Inlet valve, closing of, 8.

Inspection of car, 220.

Insulators, 76.

Interrupter points, smoothing, 295.

Irreversible steering mechanism, 165.

Jack shaft, 152.

Jackets, water, 31.

Joints universal, necessity for, 144.

Jump spark system, action of, 96.
circuit of, 108.

Jump spark trouble, location of, 205.

Jump spark wiring, 238.

Kerosene, use of, for cleaning, 224.

Knocks, 217.

Lead and return wires, 78.

Leaks of compression, 197.

Limit of compression, 14.

Lines of force, magnetic, 87, 251.

Live rear axle, 146.

Losses of heat, 15.