Figure 3-2. Rotor Checks.

TM 10-3930-633-34

separate the drive end frame (5) from the rotor

(3) Place a piece of tape over the slipring end

shaft.

frame bearing (11) to prevent entry of dirt.

(6) Further disassembly should be per-

(4) To remove the drive end frame from the

formed only as necessary, as outlined in the

rotor, place the rotor in a vise and tighten only

following subparagraphs.

enough to permit removal of the shaft nut (1).

d. Rotor Checks. The rotor must be checked

CAUTION

Avoid excessive tightening as this may

electrically for grounded, open, or short circuited

field coils, using an ohmmeter as shown in figure

cause distortion of the rotor.

3-2.

(5) Remove the shaft nut (1), washer (2),

pulley (35), fan (36) and the collar (3), and then

Figure 3-2. Rotor Checks.

resistance of the field by connecting an ohmmeter

(1) To check for grounds, connect a 110-volt

test lamp or an ohmmeter from either slipring to

to the two slip rings. If the resistance reading is

the rotor shaft or to the rotor poles. If the lamp

below the specified value, the winding is shorted.

lights, or if the ohmmeter reading is low, the field

The specified resistance value can be determined

winding is grounded.

by dividing the voltage by the current given in

Tabulated Date, paragraph 1-8.

(2) To check for opens, connect the test lamp

or ohmmeter to each slipring. If the lamp fails to

(4) Replace the rotor if any of these checks

light, or if the ohmmeter reading is high (infinite),

reveal a defect.

the winding is open.

e. Stator Checks. To check the stator wind-

(3) The winding is checked for short circuits

ings, remove all three stator lead attaching nuts

by connecting a battery and ammeter in series:

and then separate the stator assembly from the

with the two sliprings. Note the ammeter reading

end frame. The fit between stator frame and end

and refer to specifications. An ammeter reading

frame is not tight, and the two can be separated

above the specified value indicates shorted

easily.

windings. An alternate method is to check the

3-3