Checking the Commutator

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

Standard value
Armature run-out : 0.05 mm (0.002 in.)

Limit
Armature run-out : 0.1 mm (0.0039 in.)




2. Check the outer diameter of the commutator.

Standard value
Outer diameter of the commutator: 29.4 mm (1.157 in.)

Limit
Outer diameter of the commutator: 28.4 mm (1.118 in.)




3. Check the depth of the undercut between segments.

Standard value
Depth of the undercut between segments 0.5 mm (0.020 in.)

Limit
Depth of the undercut between segments 0.2 mm (0.079 in.)