The differential lock represented in the figure operates according to the principle of the visco-hydraulic clutch.
In the design shown, the visco-hydraulic clutch transfers a frictional torque between the output shaft and the differential housing. This results in the relative motion between the wheels being impaired. The magnitude of the frictional moment depends exclusively on the speed of the lamellae against each other. Through a suitable layout (temperature and pressure development in silicone oil), an increased locking effect can be achieved by the so-called "Hump-effect".