Intermediate reduction drive (Operation): Description and operation

Operation

Drive is transmitted from the gearbox to the IRD primary shaft via the splined hub in the gearbox final drive gear carrier. The drive is then transmitted from the primary shaft gear, which is integral with the primary shaft, to the layshaft which in turn drives the differential for the front driveshafts, and via a bevel drive gear and pinion to drive the rear axle. The intermediate shaft passes through the centre of the IRD primary shaft, and is the drive link between the IRD differential, and the left-hand front driveshaft, passing through the centre of the final drive carrier.

Oil Seals

1 Primary shaft outer oil seal 2 Primary shaft inner oil seals 3 RH drive shaft oil seal

4 Pinion housing oil seal 5 'O' ring seal

Externally, three oil seals prevent lubricating oil escaping from the gearbox and the IRD unit. The gearbox gear case houses the oil seal for the left-hand front driveshaft, and the RH housing on the IRD unit houses the oil seal for the right-hand front driveshaft, with the remaining oil seal located in the pinion housing of the IRD.