Piper Comanche PA-24 Service Manual page 712

PIPER COMANCHE SERVICE MANUAL
should be disassembled only so far as is necessary
to make repair or replacement of the defective
parts. As a precaution, wear safety glasses when
disassembling the cranking motor. Following are
general instructions for disassembling a typical
Bendix dri ve cranking motor:
a. Remove the cover band, if present,
and detach the field coil leads from the brush
holders.
b. If gear reduction, remove the drive
housing, and reduction housing.
c. Remove the bolts attaching the drive
housing and commutator end frame to the field
frame assembly. Discard the tang lock washers.
d. Separate the commutator end fratTI'
armature assembly, field frame, and dri .
housing.
BATTERY
AMMETER
CRANKI~NG~~~~~S~TA~L~L~P:::OSITtON
OF BRAKE ARM)'
uOTOA'
12'
I
e. Remove and disassemble the drive ' - - - - - - - - - - - - - - - -_ _ _ ---'
from the armature shaft by first identifying the type
Bendix drive and then following one of the guides
below:
Figure 9-27u. Lock-Torque Test
removed.
I. Standard Bendix Drive, remove the head spring screw and slip it off of the armature shaft.
2. Folo-Thru-Bendix Drive, push in the outer anchor plate so the pilot screw or pin can be
NOTE
Some Folo-Thru Drives use a rubber cushion in place of a drive spring. To
remove from shaft, screw pinion out to drive position, then force pin from
shaft through screw sleeve holes.
CAUTION
Do not disassemble this drive, service is by complete replacement.
9-71. Component Inspection And Repair.
a. Brushes and Brush Holders - Inspect the brushes for wear. If they are worn down to one-half
their original length, when compared with a new brush, they should be replaced. Make sure the brush holders
are clean and the brushes are not binding in the holders. The full brush surface should ride on the commutator
with proper spring tension (refer to test specification) to give good, firm contact. Brush leads and screws
should be tight and clean.
b. Armature - The armature should be checked for short circuits, opens, and grounds:
I. Short circuits are located by rotating the armature in a growler with a steel strip such as a
hack saw blade held on the armature. The steel strip will vibrate on the area of the short circuit. Shorts
between bars are sometimes produced by brush dust or copper between the bars. Undercutting the insulation
will eliminate these shorts.
2. Opens - Inspect the points where the conductors are joined to the commutator for loose
•
ELECTRICAL SYSTEM
Revised: 8115198 •
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