Figure 5-26. Checking Commutator Runout F10000RG-2

TM5-4110-234-14

TO 40R7-5-7-1

(3) Testing the Armature for Open Circuit: The most common place for an open circuit to occur is at the

commutator riser bars. Inspect the points where the conductors are joined to the commutator bars for loose connections.

(4) Testing Commutator Runout: Place the commutator in a test bench and check runout with a dial indicator (fig.

5-26). When commutator runout exceeds 0.004 inch (.010 cm), reface the commutator.

Figure 5-26. Checking Commutator Runout F10000RG-2

(5) Testing Armature Shaft Runout: The armature shaft, as well as the commutator, may be checked. A bent

armature can often be straightened, but if the shaft is worn, a new armature is required (fig. 5-27).

Figure 5-27. Checking Armature Shaft Runout F10000RG-2

5-46