Purpose of the differential

The differential ensures that the right and left drive wheels roll with different speeds when turning the car and when driving on rough roads. The differential transmits torque from the propeller shaft of the gearbox via a bevel gear to the two rear wheel drive shafts.

Rectilinear motion

Both rear wheels have the same speed as the differential gear. The differential bevel gear gears rotate evenly.

Driving in corners

A wheel passing through the outer radius travels a longer distance than the inner one. The different speeds of the wheels equalize, otherwise one of them would constantly slip in the corners.

This is what the bevel gear does: the faster rotation of the outer bevel gear is transmitted through the idler gears to the outer gear, which turns more slowly.