The starter solenoid may be located away from or on the starting motor. When mounted away from the starter, the solenoid only makes and breaks electrical connection. When mounted on the starter, it also slides the pinion gear into the flywheel.

In operation, the solenoid is actuated when the ignition switch is turned or when the starter button is depressed. The action causes current to flow through the solenoid (causing a magnetic attraction of the plunger) to ground. The movement of the plunger causes the shift lever to engage the pinion with the ring gear. After the pinion is engaged, further travel of the plunger causes the contacts inside the solenoid to close and directly connects the battery to the starter.

If cranking continues after the control circuit is broken, it is most likely to be caused by either shorted solenoid windings or by binding of the plunger in the solenoid. Low voltage from the battery is often the cause of the starter making a clicking sound. When this occurs, check all starting circuit connections for cleanliness and tightness.

FIELD FRAME. - The field frame is the center housing that holds the field coils and pole shoes.

The field coil (winding) is a stationary set of windings that creates a strong magnetic field around the motor armature. When current flows through the winding, the magnetic field between the pole shoes becomes very large. Acting against the magnetic field created by the armature, this action spins the motor with extra power. Field windings vary according to the application of the starter motor. The most popular configurations are as follows (fig. 2-41):

TWO WINDINGS, PARALLEL - The wiring of the two field coils in parallel will increase their strength because they receive full voltage. Note that two additional pole shoes are used. Though they have no windings, their presence will further strengthen the magnetic field.

FOUR WINDINGS, SERIES-PARALLEL - The wiring of four field coils in a series-parallel combination creates a stronger magnetic field than the two field coil configuration.

FOUR WINDINGS, SERIES - The wiring of four field coils in series provides a large amount of low-speed torque, which is desirable for automotive starting motors. However, series- wound motors can build up excessive speed if

Figure 2-41. - Field winding configurations.