Assignment

In multi-track vehicles with two driven wheels or four-wheel drive, the final drive gears should distribute the torque and at the same time compensate for the wheel-speed differences, e.g., when cornering.

Function

It is also called 'differential'. The spur-wheel differential uses planet gears to compensate, however, this mostly occurs through four bevel wheels which are all meshed with each other.
The drive takes place through the (shown in black) casing on two or four (above figure) of the opposing compensating bevel wheels. When driving in a straight line they do not turn. The whole bevel wheel gear-set revolves as a block and transfers the torque to both axle shaft wheels evenly.
Only when there are wheel speed differences (e.g., when cornering) between the two axle shaft wheels, both differential bevel pinions turn in opposite directions on their shafts in the casing. The torque is always evenly distributed to both driven wheels. The wheel with the greatest slip determines the transferable torque. It is highest when the slip of both wheels is about 0% - precisely 0% is impossible when driving. To prevent wheel-spinning of a driven wheel, and to achieve the transferable torque, a differential lock is necessary. Differential gears also appear between the axles of a permanent all-wheel-drive.

Important

With wheel speed differences between the axle shaft wheels, one wheel turns more slowly,- accordingly, the other wheel turns faster. In extreme cases, one wheel stands still, while the other turns twice as fast. 03/09