7.15
Section 7
Electrical System and Components
7
Inspection
Drive Pinion
Check and inspect the following areas:
a. The pinion teeth for abnormal wear or damage.
b. The surface between the pinion and the clutch
mechanism for nicks, or irregularities which
could cause seal damage.
c. Check the drive clutch by holding the clutch
housing and rotating the pinion. The pinion
should rotate in one direction only.
Brushes and Springs
Inspect both the springs and brushes for wear,
fatigue, or damage. Measure the length of each brush.
The minimum length for each brush is
7.6 mm
(0.300 in.)
. See Figure 7-28. Replace the brushes if they
are worn undersize, or their condition is
questionable.
Figure 7-29. Commutator Mica Inspection.
2. Use an ohmmeter set to the Rx1 scale. Touch the
probes between two different segments of the
commutator, and check for continuity. See Figure
7-30. Test all the segments. Continuity must exist
between all or the armature is bad.
Figure 7-28. Checking Brushes.
Armature
1. Clean and inspect the commutator (outer
surface). The mica insulation must be lower than
the commutator bars (undercut) to ensure
proper operation of the commutator. See Figure
7-29.
Figure 7-30. Checking Armature.
3. Check for continuity between the armature coil
segments and the commutator segments. See
Figure 7-30. There should be no continuity. If
continuity exists between any two, the armature
is bad.
4. Check the armature windings/insulation for
shorting.
Shift Fork
Check that the shift fork is complete, and the pivot
and contact areas are not excessively worn, cracked,
or broken.
Wear Limit Length
7.6 mm (0.300 in.)
Mica Insulation
Commutator O.D.
Insulation
Check
Armature
Coil
Continuity Check
