Page 189 - CTS - Mechanic Diesel - TP

MECHANIC DIESEL - CITS

TASK 7: Test for open circuit in Rotor winding
1 Check the motor winding continuity by connecting a12 V/ 24 V battery and the moving coil ammeter between
the slip-rings.

The current should be 2 to 2.5 Aapproximately for 12 V. If it is not of the correct value then renew the rotor.
2 Check the resistance of the rotor winding with an ohmmeter.
3 The resistance should be 9.6 to +/- 1 ohms for a 24 V alternator and 3.2 +/- 0.5 ohms for a 12 V alternator. If
the readings are not within the limit, renew the rotor assembly.

TASK 8: Testing diodes
1 Test each diode separately by connecting a 12 V battery and 12 V, 15 W bulb in series with the diode.
Connect one test lead to the diode connecting pin and the other lead to the heat sink. (Fig 1)

Fig 1

2 Watch if the lamp glows. Then reverse the test lead connections. The lamp should glow during one direction
of the test connection only.
3 Replace the diode if required.

TASK 9: Check the slip rings
1 Check the slip-rings(12) for their trueness in a lathe and with a dial test indicator. Check the surface of the slip-
ring for burnt or dirt. Replace the slip-ring, if required.
While assembling ensure that the scribed reference lines are in alignment.
2 Assemble the rotor assembly (21) with the drive and bearing (22) to the drive end bracket (14) and fix the
bearing retainer (24) with screws.
3 Assemble the spacer (18) woodruff key (20), fan (19) and pulley (17) on the rotor shaft (23).
4 Assemble the stator assembly (13) to the drive end bracket (14).
5 Place the rectifier assembly to the slip-ring end bracket and fix the screws.

6 Place the slip-ring end bracket (9) and fix the fixing bolt/stud.
7 Solder the stator winding cable ends to the rectifiers.
8 Place the brush-box on the slip-ring end bracket (9) and fix the screws.
9 Place the sealing pad and place both the brushes.

10 Place the delivery brush mounting plate in position and fix the screws.
11 Place the regulator (4) on the brush-box and connect the regulator leads (3) & (5) and fix the screws.
12 Place the cover and fix the cover securing studs (1) and washer (10) and tighten the nuts (2) firmly.

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CITS : Automotive - Mechanic Diesel - Exercise 10.2