Health check
If there is any doubt about the efficiency of the starter, it is necessary to check it on the stand.
The electrical connection diagram for testing the starter on the stand is shown in fig. 7-17. Connecting wires to the current source, ammeter and contact bolt of the starter traction relay must have a cross section of at least 16 mm.
Pic. 7-17. Connection diagram for testing the starter on the stand:
1 - voltmeter with a scale limit of at least 15 V;
2 - starter;
3 - 800 A rheostat;
4 - ammeter with shunt for 1000 A;
5 - switch;
6 - battery.
The temperature of the starter during checks should be (25±5) °C, and the brushes are well lapped to the collector.
Closing switch 5, at a voltage of the current source of 12 V, turn on the starter three times with different braking conditions. For example, with braking torques of 3, 6 and 12 Nm (0.3; 0.6 and 1.2 kgf·m). The duration of each starter activation should be no more than 5 s, and the intervals between starts should be at least 5 s.
If the starter does not rotate the ring gear of the stand or its operation is accompanied by abnormal noise, then disassemble the starter and check its parts.
Full brake test
Slow down the ring gear of the stand, turn on the starter and measure the current, voltage and braking torque, which should be no more than 700 A, no more than 5 V and no less than 13.72 Nm, respectively (1.4 kgf·m). The duration of the starter activation should be no more than 5 s.
If the braking torque is lower and the current strength is higher than the specified values, then this may be due to an inter-turn short circuit in the armature winding or a winding short circuit to ground.
If the braking torque and current consumption are below the specified values, then the cause may be oxidation and contamination of the collector, severe wear of the brushes, brushes hanging in the brush holders, loosening of the brush leads, oxidation or burning of the contact bolts of the traction relay.
At full braking, the starter drive shaft should not rotate; if it does, the freewheel is defective.
To troubleshoot, disassemble the starter and replace or repair damaged parts.
Idling test
Disengage the ring gear of the stand from engagement with the starter gear. Turn on the starter and measure the current consumed by it and the speed of the starter drive shaft, which should be no more than 80 A and 3000 min-1, respectively, with a voltage at the starter terminals of 11.5-12 V.
If the current and speed of the drive shaft differ from the specified values, then the reasons may be the same as in the previous test.
Checking the traction relay
Install between restrictor ring 13 (see fig. 7-15) and gear spacer 11.5mm thick and turn on the relay. The switching voltage of the relay when the gear rests on the gasket should be no more than 8 V at ambient temperature (20±5) °C. If the voltage is higher, then this indicates a malfunction of the relay or actuator.
Pic. 7-15. Starter 57.3708:
1 - collector;
2 - back cover;
3 - stator housing;
4 - traction relay;
5 - relay armature;
6 - cover on the drive side;
7 - lever;
8 - lever bracket;
9 - sealing gasket;
10 - planetary gear;
11 - drive gear;
12 - cover insert;
13 - restrictive ring;
14 - drive shaft;
15 - overrunning clutch;
16 - layering ring;
17 - drive shaft support with insert;
18 - gear with internal gearing;
19 - carrier;
20 - central gear;
21 - armature shaft support;
22 - permanent magnet;
23 - anchor;
24 - brush holder;
25 - brush;
26 - output «50» traction relay;
27 - screws for fastening the brush holder;
28 - tie rod with nut.