Figure 3-19. Setup for bench testing pump motor.

TM 10-3930-609-35

Figure 3-19. Setup for bench testing pump motor.

q. Using a spring balance, check force of brush

j. Insert ball bearing into bearing bore of rear

springs against brushes, brush springs must bear

motor yoke.

against brushes with 2.5 to 3 pound force. Replace

k. Carefully aline match marks on rear motor yoke

brush springs if tension requirements are not met.

with match marks on motor ring, guiding rear end of

motor shaft into ball bearing in rear yoke. Secure rear

Caution

yoke to motor ring with eight capscrews and

Do not apply voltage greater than 12

lockwashers.

volts dc to pump motor terminals

l. Install retaining ring in groove at rear end of

unless load is applied to motor.

armature shaft.

Motor will overspeed if higher

m. Install bearing retainer in rear yoke with three

voltage is applied without motor

screws and lockwashers.

loadings.

n. Before continuing assembly of motor, check that

r. Clamp motor to bench and apply 12 volts dc to

armature rotates freely without binding or dragging at

terminals S1 (positive) and A2 (negative). Check that

any point. If binding or dragging is detected, locate and

rotation is clockwise as viewed from commutator end of

correct cause of trouble before proceeding.

armature shaft.

o. Insert brushes into brushholders and secure

s. While motor is running, lightly stone

shunts and jumpers to brushholders with machine

commutator if excessive sparking at brushes is

screws, flatwashers and lockwashers.

The proper

observed. Disconnect motor from power source.

internal connections are shown in figure 3-18.

t. Install covers on front yoke and secure with cap

p. Install brush springs on brushholders and secure

screw, nut and lockwasher.

with cotterpins.

3-34