Initial Inspection and Diagnostic Overview

CHECKING THE COMMUTATOR




1. Place the armature on a pair of V-blocks, and check the runout by using a dial gauge.

Standard value: 0.05 mm (0.002 in.)
Limit: 0.1 mm (0.0039 in.)




2. Check the outer diameter of the commutator.

Standard value: 29.4 mm (1.157 in.)
Limit: 28.4 mm (1.118 in.)




3. Check the depth of the undercut between segments.

Standard value: 0.5 mm (0.020 in.)
Limit: 0.2 mm (0.0079 in.)

BRUSH HOLDER




Check for continuity between the brush holder plate and the brush holder.

The normal condition is no continuity.

OVERRUNNING CLUTCH




1. While holding clutch housing, rotate the pinion. Drive pinion should rotate smoothly in one direction, but should not rotate in opposite direction. If clutch does not function properly, replace overrunning clutch assembly.
2. Inspect pinion for wear or burrs. If pinion is worn or burred, replace overrunning clutch assembly. If pinion is damaged, also inspect ring gear for wear or burrs.

FRONT AND REAR BRACKET BUSHING
Inspect bushing for wear or burrs. If bushing is worn or burred. replace front bracket assembly or rear bracket assembly.

TESTING ARMATURE
Testing Armature For Short-Circuit




1. Place armature in a growler.
2. Hold a thin steel blade parallel and just above while rotating armature slowly in growler. A shorted armature will cause blade to vibrate and be attracted to the core. Replace shorted armature.


Testing Armature For Grounding




Check the insulation between the armature coil cores and the commutator segments. They are normal it there is no continuity.

Checking For Armature Coil Wiring Damage/Disconnection




Check for continuity between segments. The condition is normal if there is continuity.