For Internal Office Use Only
9.1 SIGNAL MEASURING AT THE DRIVER
CONTROL UNIT
Drive rheostat switch S8:
This switch is located at the accelerator and is closed after pedal actuation. Then
the battery plus signal is transferred to the coil of the K4 relay and the relay closes
the switching contact.
Relay K4:
After the drive rheostat switch S8 has closed, the battery plus signal applies at the
K4 relay’s coil and closes the switching contact. This contact is located in series with
the direction switch S7 between the control unit A1:X3:1 and S7.
Now the battery minus signal can be transferred from A1:X3:1 via the switching
contact of K4 and the direction selector switch S7 to the drive control unit.
Battery minus at A4:X51:4 -> forward
Battery minus at A4:X51:5 -> reverse
Now the direction contactors of the drive control unit close contact.
Result for drive direction:
If the drive control unit does not switch the direction contactors after drive direction
has been selected and the accelerator actuated, check the above mentioned signals/
voltages, connections, switches etc.
