This locks the half-shaft to the centre and hence locks the diff'. It is necessary to stop and operate this diff' lock with a spanner, and it can only be fitted to the rear axle of a vehicle with fully-floating axles, but it is very simple which is no bad thing. This type was initially developed for Rover differentials and used in competition on a Range Rover in the Malaysian Rainforest Challenge , winning in 1998. The original alloy housing tended to crack as the front axle twisted when cross-axled, but current iron castings are stronger. In some ways a diff' lock is the ultimate traction device.
All wheels revolve at the same speed when engaged.
A vehicle with locks on all axles has traction if just one wheel does. The components had better be able to stand the strain. Some diff' locks come with strengthened half-shafts and other components for this reason. The perfect differential would provide little or no resistance to the differential action when the difference in rotational speed between the output shafts is small, ie. It would provide increasing resistance as the difference in speed increases, ie.