L322 Range Rover System Description and Operation
TRANSFER BOX
41-6
DESCRIPTION AND OPERATION
Description
General
The NV225 Transfer Box is a full time, permanent four wheel drive, torque splitting transmission with equal torque
distribution to the front and rear propeller shafts. The transfer box has the following features:
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Permanent four wheel drive with 50/50 torque split
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Two speed, fully synchronised 'shift on the move' system with electronic control and operation
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High range direct drive and low range via epicyclic gearset
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Torsen® Type B torque sensing and torque biasing centre differential
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Self lubricating oil pump system.
The transfer box is located under the vehicle in a subframe, behind the transmission. The units used on both the Td6
and V8 variants are identical, with the exception of the large mounting bush. The transfer box is manufactured by New
Venture Gear in Roitzsch, Germany.
The transfer box receives an input from the transmission output shaft which is passed through the unit to two outputs
for the front and rear propeller shafts.
The transfer box provides full time four wheel drive via a 50:50 torque sensing Torsen® differential. The unit design
allows “shift on the move” from high to low range and visa versa. A planetary gearset with helical planetary pinion
gears provides low range operation. When in low range, the planetary gearset provides a ratio of 2.69:1 which gives
the vehicle an extremely low, low range crawl speed. High range is a direct drive from the transmission output shaft
and provides a 1:1 ratio.
The transfer box has electronic control, via a PWM actuator (DC motor), on the shift from high to low range. The
actuator is controlled by a transfer box ECU, which is located behind the battery in the engine compartment.
