Piper COMANCHE PA-24-180 Service Manual page 588

PIPER COMANCHE SERVICE MANUAL
STARTING MOTOR
FIGURE 9-29a. NO-LOAD TEST HOOKUP
FIGURE 9-29f. STALL-TORQUE HOOKUP
play should be .005 to .050 of an inch.
b. New brushes should be properlyseated when installing by wrapping strip of 00 sandpaper
around the commutator (with the sanding side out) 125 to 1.50 times maximum. Drop brushes on
sandpaper covered commutator and turm the armature slowly in the direction of rotation. Dust
should be blown out of the motor after sanding.
NOTE
The spring tension is 32 to 40 ounces with new brushes. This ten-
sion is measured with the 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 specifications for unit for correct dimensions. Refer to paragraph 9-90.
9-88. 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 specifications as given in paragraph 9-90. To make this test, con-
nect as shown in Figure 9-29e. 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 raw-
hide 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 9-29f.
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 in good order.
replace frame and field assembly and retest starter.
ELECTRICAL SYSTEM
ISSUED: 8/18/72
3 C18