Figure 11-24. Stall Torque Hookup
—NOTE—
The spring tension is 32 to 40 ounces with new brushes. This tension is
measured with a spring scale hooked under the brush spring near the
brush and the reading is taken at right angles to the line of force
exerted by the brush spring.
c. Check the position of the pinion to be sure the unit will mesh properly with the flywheel ring gear. See
Paragraph 11-51 and Table XI-V for specifications.
11-49. BENCH TESTS.
a. After the starting motor is reassembled, it should be tested to see that the no load current at a certain
voltage is within specification as given in Paragraph 11-51. To make this test, connect as shown in Figure 11-23.
If current is too high, check the bearing alignment and end play to make sure there is no binding or interference.
Two or three sharp raps on the frame with a rawhide hammer will often help to align the bearings and free the
armature.
b. If no difficulty is indicated in the above test, a stall torque test may be made to see if the starting motor is
producing its rated cranking power. Make test connections as shown in Figure 11-24.
c. If torque and current are not within specifications, check the seating of the brushes and internal
connections for high resistance. If these checks are made and found to be good order, replace frame and field
assembly and retest starter.
378
KNIFE SWITCH
VOLTMETER
CARBON PILE
AMMETER
BATTERY
STARTING
MOTOR
GROUND
SPRING SCALE
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
ELECTRICAL SYSTEM
2D19