Starting Motors (Prestolite); Exploded View Starting Motor; Description; Operation - Piper Navajo Chieftain PA-31-350 Service Manual

374
C.E. HEAD
ASS'
BRUSH SET
BRUSH
SPRING SET
COVER
BAND
SEALED
BALL BEARING
ARMATURE
BUSHING
SET
NEEDLE
BEARING
FRAME & FIELD
ASS'Y
GEAR
ENDIX DRIVE
BENDIX DRIVE SHAFT
PINION HOUSING A
SS'Y
•THRUST WASHER PKG.
Figure 11-23. Exploded View Starting Motor
11-30. STARTING MOTORS (Prestolite).
11-31. DESCRIPTION. The gear reduction starting motor consists of six major components: The
Commutator End Head Assembly, The Armature, The Frame and Field Assembly, The Gear Housing, The
Pinion Housing, and The Bendix Drive Assembly. (Refer to Figure 11-23.)
11-32. OPERATION. When the starting circuit is energized, battery current is applied to the starting
motor terminal. Current flows through the field coils, creating a strong magnetic field. At the same time,
current flows through the brushes to the commutator, through the armature winding to ground. The
magnetic force created in the armature combined with that created in the field windings begins to turn the
armature.
The gear cut on the drive
end
of the armature shaft extends through the gear housing, where it is
supported by a roller bearing. The gear mates with the teeth of the reduction gear that drives the bendix
shaft. The shaft is keyed to the reduction gear. The Bendix drive is held in position on the shaft by a
"spirol" pin. The shaft is supported in the gear housing by a closed end roller bearing and in the pinion
housing by a graphitized bronze bearing.
When the armature tur
the reduction gear, the Bendix drive pinion meshes with the flywheel ring
gear by inertia and action of the screw threads within the Bendix sleeve. A detent pin engages in a notch in
the screw threads which prevents demeshing if the engine fails to start when the starting circuit is
de-energized.
Reissued: 9/23/80
ELECTRICAL SYSTEM
NAVAJO CHIEFTAIN SERVICE MANUAL
3D12