Freelander System Description and Operation
INTERMEDIATE REDUCTION DRIVE
41-2
DESCRIPTION AND OPERATION
Description
Intermediate Reduction Drive (IRD)
The IRD is fitted in place of the conventional transfer box and is attached to the automatic gearbox. The combination
of the two units provides drive to the front and rear wheels. The IRD incorporates a differential unit to control the
proportion of drive delivered to each front wheel and, in addition, it operates in conjunction with the viscous coupling
to give the vehicle a self-sensing four wheel drive system. The main casing, cover and pinion housing are
manufactured from cast aluminium.
The unit comprises of a main casing, a RH housing, primary shaft, an intermediate shaft, a differential unit, a laygear,
hypoid gear set, a rear output pinion and a pinion housing.
An oil cooler, connected to the vehicle cooling system, is fitted to prevent overheating of the IRD lubricating fluid.
The main casing also incorporates the oil level/drain plugs and a breather outlet. There are a total of seven taper roller
bearings and one parallel roller bearing supporting the primary shaft, differential and output shaft assemblies.
Four seals, internal to the IRD, are used to prevent mixing of the IRD and gearbox lubricating fluids.
