Piper PA-32R-301T SARATOGA S, Maintenance Manual

Page: 807 / 956

GENERAL.
DESCRIPTION AND OPERATION.
(Refer to Figure 1.)
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. When the starting circuit is energized, battery current is applied to the start-
ing 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 windings to ground. The
magneto 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 support-
ed 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 “spiral”
pin. The shaft is supported in the gear housing by a closed end roller bearing and in the pinion housing by
a graphtized bronze bearing.
When the armature turns 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-ener-
gized.
When the engine reaches a predetermined speed, centrifugal action forces the detent pin out of the notch
in the screw shaft and allows the pinion to demesh from the flywheel.
TROUBLESHOOTING.
Troubles peculiar to the starting system are listed in Chart 1, along with their probable causes and sug-
gested remedies.
PIPER AIRCRAFT
PA-32R-301/301T
MAINTENANCE MANUAL
80-00-00
Page 80-1
Reissued: July 1, 1993
4D11