Inspection Procedure
1. ARMATURE1. Check commutator for any sign of burns of rough surfaces or stepped wear. If wear is of a minor nature, correct it by using sand paper.
2. Run-out test
Check the commutator run-out and replace if it exceeds the limit.
Commutator run-out:
Standard: 0.05 mm (0.0020 in)
Service limit: Less than 0.10 mm (0.0039 in)
3. Depth of segment mold
Check the depth of segment mold.
Depth of segment mold: 0.5 mm (0.020 in)
4. Armature short-circuit test
Check armature for short-circuit by placing it on growler tester. Hold a hacksaw blade against armature core while slowly rotating armature. A short-circuited armature will cause the blade to vibrate and to be attracted to core. If the hacksaw blade is attracted or vibrates, the armature, which is short-circuited, must be replaced or repaired.
5. Armature ground test
Using circuit tester, touch one probe to the commutator segment and the other to shaft. There should be no continuity. If there is a continuity, armature is grounded.
Replace armature if it is grounded.
2. YOKE
Make sure pole is set in position.
3. OVERRUNNING CLUTCH
Inspect teeth of pinion for wear and damage. Replace if it damaged. Rotate pinion in direction of rotation (clockwise). It should rotate smoothly. But in opposite direction, it should be locked.
CAUTION: Do not clean overrunning clutch with oil to prevent grease from flowing out.
4. BRUSH AND BRUSH HOLDER
1. Brush length
Measure the brush length and replace if it exceeds the service limit.
Replace if abnormal wear or cracks are noticed.
Brush length:
Standard 17.0 mm (0.669 in)
Service limit 11.5 mm (0.453 in)
2. Brush movement
Be sure brush moves smoothly inside brush holder.
3. Brush spring force
Measure brush spring force with a spring scale. If it is less than the service limit, replace brush spring.
Brush spring farce:
Standard: 21.6 N (2.2 kg, 4.9 lb) (when new)
Service limit: 5.9 N (0.6 kg, 1.3 lb)
5. SWITCH ASSEMBLY
Be sure there is continuity between terminals S and M, and between terminal S and ground. Use a circuit tester (set in "ohms").
Also check to be sure there is no continuity between terminal M and B.
Terminal/Specified resistance:
S-M/Continuity
S-Ground/Continuity
M-B/No continuity