Differential and Viscous Coupling Operation - Range Rover Classic

Differential And Viscous Coupling Operation - Range Rover Classic

The Morse chain 8 drives a conventional type differential 9. The front and rear output shafts 10 and 11 are splined to the differential output pinions. The front output shaft 10 forms the outer member of the viscous coupling, while the inner member plates are splined to the rear output shaft 11.

Its only function is to limit the maximum difference in speed between the two shafts, with the effect of automatically locking the differential.

The maximum difference in speed permitted by the viscous coupling must however be sufficient to allow the vehicle to be driven on a dry road surface, in a circle on full lock, without inducing 'wind up' or causing damage to the transmission.

The viscous coupling has alternate plates splined to the inner and outer members. One set of plates is splined to 10, the outer member/front shaft and the other plates are splined the rear output shaft 11. The coupling is filled with a special silicone jelly which allows sufficient slip to occur in normal driving conditions but, which increase the drag between the plates as the speed difference and temperature rises, thus eliminating the need for a manual differential lock.