Figure 2-39.Typical overrunning clutch.
and plungers hold the rollers in position in the tapered
notches. When the armature shaft turns, the rollers are
jammed between the notched surfaces, forcing the
inner and outer members of the assembly to rotate as a
unit and crank the engine.
After the engine is started, the ring gear rotates
faster than the pinion gear, thus tending to work the
rollers back against the plungers, and thereby causing
an overrunning action. This action prevents excessive
speed of the starting motor. When the starting motor is
released, the collar and spring assembly pulls the
pinion out of mesh with the ring gear.
The DYER DRIVE (fig. 2-40) provides complete
and positive meshing of the drive pinion and ring gear
before the starting motor is energized. It combines
principles of both the Bendix and overrunning clutch
drives and is commonly used on heavy-duty engines.
A starter solenoid is used to make the electrical
connection between the battery and the starting motor.
The starter solenoid is an electromagnetic switch; it is
similar to other relays but is capable ofhandling higher
current levels. A starter solenoid, depending on the
design of the starting motor, has the following
Closes battery-to-starter circuit.
Rushes the starter pinion gear into mesh with the
Bypass resistance wire in the ignition circuit.
Figure 2-40.Dyer drive.