How a car Differential Axle Works
So what, exactly, is the rear axle for and what does it do?
Well, it has three main functions -
First, to receive the power from the engine (via the gearbox and propeller shaft) and turn it through 90 degrees to the wheels;
Second, to provide an overall reduction gear, usually about 4 : 1, which saves having to make this reduction in the gearbox, thus
keeping the gearbox much smaller and enabling the straight-through top gear
ratio to be employed;
Third, to enable the wheels to travel at different speeds whilst cornering, without losing the drive.
The differential system of a vehicle is something that sounds foreign to many, yet is one of the most important parts of a vehicle. Without a differential system a vehicle is unable to handle properly when traveling around corners, curves or turning at all. All except for motorcycles must include a differential system.
The primary purpose of the differential system is to evenly distribute force to one wheel or the other depending on the drag. Both wheels will have the same force when the drag is equal. When a vehicle is in a corner the outside wheels travel further than the inside wheels, creating a problem. If all four wheels are forced to travel the same distance the vehicle will jump and skid, the differential corrects this problem. On non drive axles no differential system is needed.
Mid Engine Differential Configuration
A differential is driven by the transmission which is connected to the engine. The driveshaft connects the transmission to the differential. The differential is responsible for determining the number of rotations the axles will turn in relation to the drive shaft, a common Ratio is 2:80, the drive shaft will turn 2.8 times to one rotation of the wheel. A differential system consists of an axle housing, axles, gears, planetary gears, bearing, seals, and fluid, backing plates, brakes, assorted bolts and clips.
Smooth working helical gears are used in a differential, but a slight power loss is experienced. A straight cut gear is more efficient but smooth operation is impossible to achieve.As a normal service practice it is necessary to check the differential fluid level and add as needed. Always inspect fluid condition for metallic flakes, an indication of a problem. It is advisable to only add the best quality differential fluid as possible to ensure the proper lubrication of all moving parts. In the event that you start hearing a grinding noise coming from the rear of the vehicle, it is vitally important to inspect the differential thoroughly.
Fluid that has a burnt smell or appears blackish in color should be flushed andnew fluid installed. A differential that is low on fluid can create a differential operation failure. Once a differential has failed it must be replaced or repaired.