Inside an engine the chemical energy stored within petrol is changed to kinetic energy by combustion. A drive shaft is rotated using this energy and this connects into a gear box. The gears in this box determine how much of the engines energy is used. Another shaft then connects the gear box to the wheels via a differentials box.
Sending the power straight to the wheels from the gear box can cause difficulties. The wheels will not rotate at the same rate as each other when turning a corner, this is because they travel differing distances in the same space of time. They can be allowed to spin at different rates using a differential box.
Cars will have this system implemented at different places on them depending on which set of wheels the power from the engine is directed. A rear wheel drive car will have the differential at the back of the car while a front wheel drive car will have it at the front. A four will drive cars has two boxes for both sets of wheels with an additional set in between.
The differential box is essentially a set of perpendicular toothed gears. The input shaft is attached to a gear at right angles two it sending changing the direction of the rotation. The simplest way in which it allows for the wheels to spin in different directions is by use of additional pinion gears attached to the gears at right angle. When the wheels spin faster these pinions allow for this whilst the other wheel continues at a slower speed.
The basic form of differential allows applies the same torque (rotational force) to each wheel however. The speed of the wheel will be limited by how much traction is available to the wheels. This means if one wheel has less grip than its counterpart it will slip, which can damage components of the car. A limited slip differential can remedy this.
The limited slip uses a mechanism which detects if one wheel is slipping while the other is not. It can direct the torque to the wheel with grip allowing the car to keep moving. It does this by using a clutch mechanism, a spring forces the gears against a clutch plate when a wheel starts to slip. A lot of torque is needed to overcome the clutch so the majority of torque is directed towards the other wheel.
To summarise what differentials allow for is for each wheel to turn at a different rate to the others. This is helpful when a car is turning a corner or when one wheel has more traction than another. Not having this system in place the wheels would slip in these scenarios and cause damage to the car.
If you’re looking to get the most traction from your differential, we recommend installing a 4 wheel part lock right locker. These units offer some of the best locking performance with a very low price that all drivers will appreciate.