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rectly to the frame. The other passes through the cutout relay and through the voltage regulator, both of which have been previously described. Six of the terminals on the distributor head, which are for ignition, are joined to the spark plugs. The remaining terminal, which is in the center of the group, is joined to the secondary terminal of the ignition coil. The circuit through the secondary is completed through a grounding wire, which is in electrical contact with the grounded bodies of the spark plugs. The insulated terminals of the spark plugs are joined to the six terminals on the distributor head. The primary winding of the ignition coil is joined to the circuit breaker through one terminal, this in turn passing through the dry battery to the ignition relay. The other terminal of the ignition coil is joined to the starting, lighting and ignition switch by a suitable conductor.
The arrangement of this switch is such that the current may be supplied directly to the head, side and tail lamps from the storage battery at all times that the switch circuit is closed. It is also possible to draw the ignition current either from the six-volt storage battery or from the battery of dry cells. The only time that the storage battery current flows through the starting motor windings is when the starting switch closes the circuit between the storage battery and the motor. At all other times the starting switch member is in such a position that the generator windings are in action and that the current from the armature is being passed into the storage battery.
Delco Motor Generator.-The motor generator which is located on the right side of the engine as at Fig. 170 is the principal part of the Delco System. This consists essentially of a dynamo with two field windings, and two windings on the armature with two commutators and corresponding sets of brushes, in order that the ignition apparatus incorporated in the forward end of the machine may work both as a starting motor, and as a generator for charging the battery and supplying the lights, horn and ignition. The ignition apparatus is incorporated in the forward end of the motor generator. This in no way affects the working of the generator, it being mounted in this manner simply as a convenient and accessible mounting.
The motor generator has three distinct functions to perform which are as follows: No. 1-Motoring the Generator. No. 2Cranking the Engine. No. 3—Generating Electrical Energy.
Motoring the Generator.—Motoring the generator is accomplished when the ignition button on the switch is pulled out. This allows current to come from the storage battery through the ammeter on the combination switch, causing it to show a discharge.
Fig. 170.-Application of Delco Motor Generator to 1916 Hudson Engine.
The first reading of the meter will be much more than the reading after the armature is turning freely. The current discharging through the ammeter during this operation is the current required to slowly revolve the armature and what is used for the ignition. The ignition current flows only when the contacts are closed, it being an intermittent current. The maximum ignition current is obtained when the circuit is first closed and the resistance unit on the rear end of the coil is cold. The current at this time is approximately 6 amperes, but soon decreases to approximately 342 amperes. Then as the engine is running it further decreases until at 1,000 revolutions of the engine it is approximately 1 ampere.
This motoring of the generator is necessary in order that the starting gears may be brought into mesh, and should trouble be experienced in meshing these gears, do not try to force them, simply
Fig. 171.-Diagrams Explaining Construction of Delco Motor Generator
Having Third Brush Current Control.
allow the starting pedal to come back, giving the gears time to change their relative position.
Generator Clutch.-A clicking sound will be heard during the motoring of the generator. This is caused by the overrunning of the clutch in the forward end of the generator which is shown in view 1, Fig. 171.
The purpose of the generator clutch is to allow the armature to revolve at a higher speed than the pump shaft during the cranking operation and permitting the pump shaft to drive the armature
when the engine is running on its own power. A spiral gear is cut on the outer face of this clutch for driving the distributor. This portion of the clutch is connected by an Oldham coupling to the pump shaft. Therefore, its relation to the pump shaft is always the same and does not throw the ignition out of time during the cranking operation. This clutch receives lubrication from the oil that is contained in the front end of the generator which is put in at B (view 1). This is to receive oil each week sufficient to bring the oil up to the level of the oiler. The arrangement of clutch parts is shown at Fig. 172.
Cranking Operation. The cranking operation takes place when the starting pedal is fully depressed. The starting pedal brings the