Range Rover P38
41
TRANSFER BOX
NEW RANGE ROVER
12
DESCRIPTION AND OPERATION
TRANSFER BOX - OPERATION
Transfer Box
Drive is transmitted to the transfer box from the
gearbox output shaft which is permanently engaged in
the sun gear of the epicyclic gear set. In high range
the sun gear transmits drive directly to the selector
sleeve. In low range, when the selector spool has
moved the selector sleeve, the sun gear transmits
drive through the planet carrier.
The rotation of the selector sleeve is transferred to the
intermediate shaft. A gear attached to the
intermediate shaft carries the morse chain which
transfers the drive to the differential unit.
The rear output shaft passes through the differential
unit and rotates at the same speed. The viscous
coupling passes drive from the rear output shaft to the
front output shaft. When the silicon fluid in the viscous
coupling becomes warm its resistance to shear
increases passing more drive to the front drive shaft
increasing traction.
Electrical Operation
Range change
NOTE: Range changes should be
performed with the vehicle stationary and
although range changes are possible at
very low speeds, this practice is not
recommended.
Automatic transmission
To change range the vehicle speed must be reduced
to below 5 mph (8 km/h). Move the gear selector to
neutral and then across the H-gate into the neutral
position in the selected range. The appropriate LED
illuminations on the selected range side of the selector
cover will flash and an audible warning will sound. The
flashing LED’s and the audible warning will continue
while the ratio control motor is moving the transfer box
to the selected range.
When the ratio control motor has moved the transfer
box into the selected range the LED’s will stop
flashing, the audible warning will stop and a message
is displayed in the message centre. The desired gear
can be selected and the vehicle can be driven as
required.
If the vehicle is moving above 5 mph (8 km/h) or the
selector lever is moved into gear before the range
change is complete, the change will not occur and a
’SLOW DOWN’ or ’SELECT NEUTRAL’ message will
be displayed in the message centre.
NOTE: The ’SLOW DOWN’ message is
generated by the BeCM, not the transfer
box ECU.
The transfer box can be placed in the ’Neutral’
position by moving the selector lever into the ’PARK’
position. Insert a spare fuse (minimum 5 Amp) into
fuse position 11 on the BeCM. After 5 seconds the
transfer box moves to the neutral position, an audible
warning will sound, a ’TRANSFER NEUTRAL’
message is displayed in the message centre and the
high and low LED illumination on the selector cover
will extinguish.
Manual transmission
To change from high to low the vehicle speed must be
below 5 mph (8 km/h) or from low to high the vehicle
speed must be below 15 mph (24 Km/h).
Select neutral with the gear lever and press the
high/low switch on the fascia. The indicator lamp on
the switch will flash as the range change takes place.
If the change is from high to low the lamp will
continuously illuminate when the change is
successfully completed. If the change is from low to
high the lamp will extinguish when the change is
complete. The message centre displays the selected
range.
If a range change is requested and the vehicle is
moving too fast or neutral has not been selected, the
indicator lamp on the switch will flash and a ’SLOW
DOWN’ or ’SELECT NEUTRAL’ message will appear
in the message centre.
NOTE: The ’SLOW DOWN’ message is
generated by the BeCM, not the transfer
box ECU.
The transfer box can be placed in the ’Neutral’
position by placing the gear lever in neutral and
inserting a spare fuse (minimum 5 Amp) into fuse
position 11 on the BeCM. After 5 seconds the transfer
box moves to neutral, an audible warning will sound
and a ’TRANSFER NEUTRAL’ message is displayed
in the message centre.