Comparison of the Systems
In extreme driving conditions, the manually operated, positively-engaged differential lock offers good improvement in traction compared to conventional differentials at a simultaneously low additional construction expense. This differential lock with its locking effect of 100% has to be released when used in general driving conditions for reasons of driving safety. It is employed in inexpensive vehicles and in the off-road-segment.
In differing driving situations, self-regulating differential locks do not require any control effort on the part of the driver or by control electronics. The locking torque is generally variable, dependent on the differential speed or load torque. The frictional torque characteristic is however fixed. Hence, for a range of frictional conditions, no favourable results can be achieved with respect to traction and driving stability.
The use of automatic lock release turns out to be problematic since their control electronics require a decoupling of the wheels. In addition there are construction-specific disadvantages such as increased wear in the locking worm differential or the response of the visco-lock, which only occurs at a considerable wheel slip.
The electronically controlled differential lock delivers optimum traction in stable driving conditions by adjusting its its map according to the specific driving condition. An antiskid device (ASD) can be taken into consideration in the program layout (withdrawal of the locking torque when braking). The high additional expense as a result of measuring detectors, microprocessors, and additional hydraulics stand in the way of broader application.