Service Training
Section 2.1
Page 8
2.1.5 FAN
Fan method of operation to 6/95:
The traction motors and pump motor are forced-air ventilated by axial-flow fan 9M1. When the operating
temperature of one of the three motors exceeds 80 °C, battery negative is applied to the fans via three thermal
switches (1B4, 1B5 and 2B5) connected in parallel. The fans are supplied with 24 V direct current over voltage
converter U1. The 80 °C thermal (make) switches are mounted on the motor brush holders.
Fan method of operation from 7/95:
In contrast to the above fan method of operation up to 6/95, thermal sensors 6B1, 6B2 and 6B3 are mounted
on the brush holders of the traction motors and pump motor. When the temperature in one of the three motors
exceeds 80 °C, +24 V is applied to axial-flow fan 9M1 and 9M2 via the combined instrument.
NOTE: The fan operates only when the key switch is turned on, i.e. the fan does not run when the key
switch is turned off.
SPECIFICATIONS FOR FAN 9M1
Rated voltage: 24 V
Voltage range: 12 - 24 V
Power consumption: 710 mA
Power: 17 W
Temperature range: -20 ... +72 °C
Rated speed: 3400 rpm
2.1.6 SPEED SENSOR
A differential speed sensor (1B8) is installed on the left-hand motor. The speed sensor senses the brake
disc bridges and supplies information regarding the motor speed and direction of rotation.
Adjustment:
The speed sensor is mounted on an angle plate on the inside bearing plate. The air gap between the active
sensor area and a web on the brake disc must be 1.0
+0.3 mm.
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