Inspection (Disassembly and Assembly)

INSPECTION

COMMUTATOR CHECK





1. Place the armature on a pair of V-blocks, and check the deflection by using a dial gauge.
Standard value: 0.05 mm (0.002 inch)
Limit: 0.10 mm (0.004 inch)






2. Check the outer diameter of the commutator.
Standard value: 29.4 mm (1.16 inch)
Minimum limit: 28.8 mm (1.13 inch)






3. Check the depth of the undercut between segments.
Standard value: 0.5 mm (0.02 inch)
Minimum limit: 0.2 mm (0.01 inch)


BRUSH HOLDER





Push the brush into the brush holder to make sure that the spring is working on the brush.
If the spring is not working, replace the brush holder.

OVERRUNNING CLUTCH





1. Make sure that the pinion cannot be turned counterclockwise, and can be turned clockwise freely.
2. Check the pinion for abnormal wear and damage.

BRUSHES





1. Check the commutator contacting surface of each brush for abnormal roughness. Also check the height of the brush. Replace the brush holder if the height is lower than the limit.
Limit: 7.0 mm (0.27 in)
2. When the contact surface of the brush is rectified or the brush holder is replaced, recondition the contact surface with sandpaper wrapped around the commutator.

ARMATURE CHECK





1. Check that the armature coil is not grounded.
2. Place the armature in a growler.
3. Hold a thin steel blade parallel and just above the armature while slowly rotating in the growler. A shorted armature will cause a blade to vibrate and be attracted to the core. Replace the shorted armature.





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





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