Contents: Checking functionality ↓ Full braking test ↓ Idle speed test ↓ Checking the traction relay ↓ Mechanical data check ↓
To ensure the efficiency of the starter, it is necessary to test its electrical and mechanical data on a bench.
The electrical circuit diagram for testing the starter on the stand is shown in Fig. 7-15. The connecting wires to the current source, ammeter and contact bolt of the starter traction relay must have a cross-section of at least 16 mm².
Fig. 7-15. Connection diagram for testing the starter on the stand: 1 - Voltmeter with a scale limit of at least 15 V; 2 - starter; 3 - rheostat 800 A; 4 - ammeter with 1000 A shunt; 5 - switch; 6 - battery
The starter must be powered by a fully charged 6ST-55P battery or by a special current source whose voltage drop characteristic under load corresponds to the voltage drop characteristic of the battery.
The temperature during checks should be 25±5°C, and the brushes should be well ground to the commutator
Checking functionality
By closing switch 5, with the current source voltage at 12 V, make four starter activations with different braking conditions. For example, with braking torques of 1.96-2.35; 5,4-6,45; 8.8-10.6 and 11.3-12.3 N·m (0.2-0.24, 0.55-0.66, 0.9-1.08 and 1.15-1.25 kgf·m). The duration of each starter activation should be no more than 5 s, and the intervals between activations should be no less than 5 s.
If the starter does not rotate the stand's ring gear or its operation is accompanied by abnormal noise, then disassemble the starter and check its parts.
Full braking test
Brake the stand's toothed ring gear, turn on the starter and measure the current, voltage and braking torque, which should be no more than 500 A, no more than 6.5 V and no less than 13.7 N·m (1.4 kgf·m), respectively. The starter engagement time should be no more than 5 s.
If the braking torque is lower and the current is higher than the specified values, then the reason for this may be an interturn short circuit in the stator and armature windings or a short circuit of the windings to ground.
If the braking torque and current consumption are lower than the values specified above, the cause may be oxidation and contamination of the collector, severe wear of the brushes or a decrease in the elasticity of their springs, sticking in the brush holders, loosening of the stator winding terminals, oxidation or burning of the contact bolts of the traction relay.
When the gear is fully braking, the starter anchor should not turn; if this happens, the freewheel clutch is faulty.
To troubleshoot, disassemble the starter and replace or repair damaged parts
Idle speed test
Remove the toothed ring gear of the stand from engagement with the starter pinion. Turn on the starter and measure the current it consumes and the rotation speed of the starter anchor, which should be no more than 35 A, respectively (60A for starter 35.3708) and 5000+500-800 min⁻¹ WHEN the voltage at the starter terminals is 11.5-12 V.
If the current strength and the rotation speed of the armature shaft differ from the specified values, then the reasons may be the same as in the previous test.
Checking the traction relay
Install between the limiting ring 21 (see fig. 7-13) and a 12.8 mm thick gasket with a gear and turn on the relay. For a single-winding relay, check the current consumption, which should be no more than 23 A. For a two-winding relay, check the relay turn-on voltage, which should be no more than 9 V at an ambient temperature of (20±5)°C.
Mechanical data check
Check the spring pressure on the brushes with a dynamometer, which for new brushes should be 9.8±0.98 N (1±0.1 kgf). If the brushes are worn to a height of 12 mm, replace them, having first ground them to the commutator.
The axial free play of the anchor shaft should be 0.07-0.7 mm. If it is not within this limit, then disassemble the starter and select the thickness and number of adjusting washers 20 (Fig. 7-16).
Fig. 17-16. Starter parts: 1 - starter cover on the drive side; 2 - rubber plug; 3 - drive lever; 4 - traction relay; 5 - stator pole; 6 - series stator winding; 7 - stator shunt winding; 8 - rubber plug; 9 - protective tape; 10 - cover from the collector side; 11 - brush; 12 - brush spring; 13 - brake disc cover; 14 - body; 15 - tie rod; 16 - anchor; 17 - gear travel limiter; 18 - overrunning clutch with drive gear, 19 - thrust washer; 20 - adjusting washer
The starter drive must move freely along the splined shaft without noticeable jamming and return from the working position to the original position under the action of the return spring of the relay armature.
When turning the drive gear in the direction of rotation of the anchor, the anchor should not rotate. The gear should rotate relative to the anchor shaft under the action of a torque of no more than 27.4 N·cm (2.8 kgf·cm).