a) Positively-Engaged Differential Locks
The most simple and obvious design of a differential lock involves a positively-engaged combination that connects the output shaft with the planetary support and in turn with the other output shaft. With an engaged clutch (lock), the behaviour of the output corresponds to the one of an undivided shaft. The locking value amounts to 100%.
The clutch is manually engaged by the driver over a gearshift linkage or gearshift hydraulics. The figure above illustrates a positively-engaged bevel-gear differential lock and a corresponding spur-gear differential.
The manual operation of positively-engaged differential locks requires higher attention on the part of the driver since a locked differential during normal driving leads to higher tire wear, additional stress on the drive train, ABS malfunction, and deterioration in the maneuverability of the vehicle due to the absence of speed compensation.