immediately with the armature shaft. It remains
stationary for a time because of the inertia of the
counterweight, and then runs along the revolving
threaded sleeve until it engages the ring gear. Should
the pinion meet but not engage the ring gear, the drive
spring is compressed. This allows the pinion to turn and
engage the ring gear.
When the pinion and ring gear are engaged, the
Figure 6-67.--Bendix drive construction.
pinion is driven by the starting motor through the drive
BENDIX DRIVE.--This type of drive consists of
spring and turns the engine. The drive spring
a pinion and sleeve (shaft) assembly, a drive spring, and
compresses to absorb the shock of initial pinion
a drivehead (fig. 6-67). The pinion is counter weighted
engagement and cushions the starter drive against the
on one side and has internal spiral threads. The pinion is
compression of the engine as the engine is being turned.
mounted on a sleeve and has external threads that match
When the engine fires and runs on its own power, the
those of the pinion. The sleeve is a loose fit on the motor
ring gear drives the pinion at a higher speed than the
armature shaft. One end of the sleeve is bolted to the
starting motor, and the pinion runs back along the
drive spring and the other end of the drive spring is
threaded sleeve to its original, disengaged position.
bolted to the drivehead. The drivehead is keyed and
There are several other versions of Bendix drives in use,
bolted to the armature shaft by the shank of the same
but they all operate on the same principle and have
bolt that holds the drive spring to the drivehead.
essentially the same construction.
When the starter is not operating, the pinion is
OVERRUNNING CLUTCH.--The overrunning
disengaged and away from the ring gear. When the
clutch drive consists of a shaft collar, a clutch spring, a
starting motor is energized, the armature immediately
shell and sleeve assembly, a pinion, a clutch rotor, and a
starts to rotate at high speed. The pinion does not rotate
set of rollers (fig. 6-68). The shell and sleeve assembly
OVER RUNNING CLUTCH
SHELL AND SLEEVE
Figure 6-68.--Solenoid shift starter and overrunning clutch drive.