Electrical Components - Design And Function: Transmission: Function: Differential
The differential distributes power equally between the drive wheels, even if they are rotating at different speeds.
When driving straight ahead, the ring wheel and differential housing rotate at the same speed as the drive shafts and the driving wheels.
When cornering, the differential gears rotate to compensate for the different speeds of the wheels. Because the small side gears are rotating on the shaft journal, the drive shafts can rotate at different speeds. Power is transferred from the differential housing to the drive shafts via the small side gears in the same way as when driving straight ahead. Both drive wheels still have the same driven power.
Cars with four wheel drive have a splined pin on the differential housing. The sleeve on the pin connects the differential housing with the bevel gear. This transfers the power to the rear wheels.