Control System Transmission - Kalmar DRF420-60S5 Maintenance Manual

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2 Transmission – 2.8 Control system transmission
2.8
Control system transmission, description
The transmission control unit controls shifting based on pressure
sensors, temperature sensors and speed sensors. Gear selection
takes place by activating solenoid valves that distribute control pres-
sure in the transmission, so that selected gear gives the correct
speed.
For position of components see Transmission, component position
page 4 and section 11 Common electrics, group 11.5.3 Control units.
In case of serious transmission problems, the control unit uses two
modes with reduced functionality to protect the transmission, Shut-
down and Limp-home.
Mode Limp-Home
Display on Control unit transmission shows LH.
In case of:
•
•
•
In case any of the above points occur, the transmission will be
placed in neutral position. To enable continued operation, gears
have to be selected using the gear selector.
In this mode the operator can use the transmission's two first gears
in both directions. If the malfunction occurs at a higher gear, the op-
erator has to downshift manually to first or second gear to continue.
The control unit uses standard values for modulation.
Mode Shut-Down
Display on Control unit transmission shows "Sd".
The transmission has a built-in secondary solenoid and pressure
sensor that monitor the transmission's internal oil pressure. The
secondary solenoid is handled by the control unit.
When the control unit gives a control signal for "Shut-Down", the oil
pressure releases for all pressure modulators. This happens in case
of a serious malfunction.
In this mode the transmission is in permanent neutral position as
there is no oil pressure to enable selection of a gear.
Maintenance manual DRF 400–450
https://www.forkliftpdfmanuals.com/

Control system transmission

a malfunction of a control output from the transmission is de-
tected.
a malfunction connected to a sensor for "engine speed" is de-
tected.
two of three "vehicle speed" sensors are defective.
11
UDRF01.04GB