Oil Seals

INTERMEDIATE REDUCTION DRIVE

41-4

DESCRIPTION AND OPERATION

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.

There are also four internal oil seals in the IRD unit. Two smaller diameter oil seals are fitted internally at each end of 
the primary shaft. These prevent oil ingress along the intermediate shaft from the IRD unit at the differential end. At 
the opposite end, the seal prevents oil ingress from the gearbox along the intermediate shaft. Two larger oil seals are 
fitted in the main casing where the IRD unit enters the gearbox. The inner oil seal prevents oil ingress from the IRD 
primary shaft entering into the area between the two seals, and the outer oil seal prevents oil ingress from the gearbox 
entering  the same area.

On the underside of the main casing is a 'tell-tale' drilling which is positioned between the inner and outer primary 
shaft oil seals. Oil leakage from the drilling will indicate either a faulty inner or outer primary shaft oil seal. An 'O' ring 
seal, fitted in a machined groove, seals the IRD main casing to the gearbox housing.