You've probably heard the term 'differential' used in car-related conversation, and you may even know what it does, but you're not quite sure how it works. You also might have seen a differential in action, whether it be in a professional racing video or during a car-related segment on television's Top Gear. Regardless of how you've encountered it, the concept is simple: A differential is a clever set of gears that allows different drive wheels (the ones to which power is delivered from the engine) on the same axle to spin at varying rates when your vehicle turns.
The basic differential is called an open diff and is found on most cars. This type of diff spreads power evenly to both wheels but, because the outside wheel has more distance to travel during a turn, it has to move faster in order to cover that additional ground. The result is that the inside wheel receives less power, which can cause the tires to lose traction and create sounds that range from clunking to howling.
To prevent this from happening, most modern vehicles have a device called a traction control system installed. This uses sensors to determine if one tire has lost traction, and it will either reduce the amount of power that's sent to the wheel or even brake that wheel in some cases. This helps to eliminate the problem of a spinning wheel with no grip, but it doesn't help when you hit ice, which is why many drivers opt for a fancier diff known as a limited slip differential. This type of diff distributes power just like the open diff, but it has special gears that can generate extra resistance when accelerating to give one wheel a bit more boost.