PRINCIPLES OF OPERATION - TM-10-3930-673-340296

TM 10-3930-673-34

6-2. PRINCIPLES OF OPERATION (CONT)

b. Starting Motor. The function of the starting motor is to turn the engine flywheel at a fast enough rate to

initiate engine combustion.

An electric solenoid, activated by the START switch, pulls the starting motor drive pinion into engagement

with the ring gear on the engine flywheel. At the same time, movement of the solenoid closes a set of switch

contacts which connect the starting motor armature to the battery through a set of four carbon brushes.

Current flow in the armature causes the armature to rotate. The drive pinion then rotates and turns the

engine flywheel. When the engine starts, centrifugal force resulting from increased flywheel speed, moves the

starting motor pinion out of engagement with the flywheel ring gear. Releasing the START switch causes the

solenoid to de-energize and disconnect the battery from the starting motor.

6-2