Intermediate reduction drive (Transfer box - IRD)

INTERMEDIATE REDUCTION DRIVE

Description

The Intermediate Reduction Drive, IRD, is fitted in place of the conventional transfer box, and is attached to the PG1 5 speed manual 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 (2), a RH housing (4), primary shaft (1), an intermediate shaft (9), a differential unit (3), a laygear (5), hypoid gear set (8), a rear output pinion (7) and a pinion housing (6). 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 PG1 lubricating fluids.