Bench Tests; Starting Motor Control Circuit; Stall-Torque Hook Up Diagram - Piper Navajo Chieftain PA-31-350 Service Manual

CARBON PILE
KNIFE SWITCH
AMMETER
VOLTMETER
Figure 11-28. Stall - Torque Hook-Up
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 11-46.)
11-44. 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 11-46. To make this test, connect as shown in
Figure 11-27. 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 11-28.
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.
11-45. STARTING MOTOR CONTROL CIRCUIT.
a.
Inspect the control circuit wiring between the battery, solenoid and manual starting switches for
breaks, poor connections and faulty insulation. Tighten all connections and make sure solenoid is firmly
mounted and makes a good ground connection.
b.
Check the voltage loss across the switch contacts during normal starting. If loss is in excess of 0.2
volts per 100 amperes, the solenoid should be replaced.
c.
If solenoid fails to operate when the manual switch is turned on or if it fails to release when the
manual switch is released, it should be removed and tested to specifications. If either opening or closing
voltages are not specified, replace the solenoid.
Reissued: 9/23/80
ELECTRICAL SYSTEM
NAVAJO CHIEFTAIN SERVICE MANUAL
3D17