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 [Fig. 93].
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.
The cranking operation takes place when the starting pedal is fully depressed. This causes the top motor brush to come in contact with the motor commutator. As this brush arm lowers, it comes in contact with the gear in the generator brush arm raising the generator brush from its commutator. At the same time the current from the storage battery flows through the heavy series field winding, motor brushes and motor winding on the armature. The switching in this circuit is accomplished by means of the top motor brush which is operated from the starting pedal. (Shown in [Fig. 94]).
This cranking operation requires a heavy current from the storage battery, and if the lights are on during the cranking operation, the heavy discharge from the battery causes the voltage of the battery to decrease enough to cause the lights to grow dim. This is noticed especially when the battery is nearly discharged; it also will be more apparent with a stiff motor or with a loose or poor connection in the battery circuit. It is on account of this heavy discharge current that the cranking should not be continued any longer than is necessary, although a fully charged battery will crank the engine for several minutes.
Brush Operating Rod
Motor Brush
Generator Brush
Generator
Commutator
Motor Commutator