ELECTRICAL SYSTEM CONTINUED
1. A simple description of the cranking motor, commonly referred to as the "starter," is an electric motor used to
rotate the engine crankshaft during the starting procedure. It is capable of producing high horsepower and
torque. This high output is restricted to very short intervals; 30 seconds or less. During its periods of operation
the motor is actually overloaded and if subjected to long periods of continuous operation will burn itself out.
2. One end of the starter is fitted with a pinion gear to engage the engine flywheel and one of several different
engagement mechanisms. Mounted on top of the motor housing is a heavy duty solenoid used to actuate the
engaging mechanism. The ratio of the drive pinion to the flywheel ring gear is approximately 15 or 20 to 1; that
is 20 teeth on the ring gear for each tooth on the pinion. This allows the starter to operate at high RPM and
exert a considerable amount of torque.
Figure 8. Diesel Engine Starter - Cross-Section.