The wheel cylinder is an important part of your breaking system if you have drum brakes. If you have other kinds of braking systems, then you will also have a similar cylinder in your car, but it will not be exactly the same as the wheel cylinder used by the drum brake. This is a vital part of the stopping mechanism of these kinds of brakes, and if one of these becomes damaged, you will need to have the whole drum replaced, rather than simply taking out the wheel cylinder and popping in a new one
