Drum brake system works just the same principles as with the dick brakes: the shoes press against the spinning surface of the drum. Most vehicles have drum brakes equipped in the rear wheels and disc brake on the front. However, drum brakes have more working components than the disc brakes and this includes the Mercury wheel cylinder, backing plate, brake drum, return springs, brake shoes, and an automatic or self-adjusting system. This assembly is actuated by a hydraulic pressure. The wheel cylinder is the device equipped with movable pistons that converts the hydraulic fluid into a mechanical force that will actuate the brake shoes to press against the brake drum. Usually, there is one wheel cylinder at each rear wheel and is typically consists of a single bore cylinder casting, an internal compression spring, two rubber seals, two pistons, two rubber boots that prohibits entry of contaminants, and a bleeder screw (valve). When you apply force to the brake pedal, the brake fluid is channeled, under pressure, through the Mercury wheel cylinder, which in turn, moves the brake shoes into contact with the machined surface of the drum brake. The brake shoes are geared with friction linings to provide a positive contact with the drum. But as the linings wear, the shoes will then be required to travel greater distance in order to reach the drum. If this distance reaches to a certain limiting point, a self adjusting mechanism will automatically adjust the rest position of the shoes so that they will move closer to the drum. Get the best value of your money by obtaining outstanding quality Mercury wheel cylinder here at our website. Through the years, we have been committed in providing you only the finest quality auto products that will answer all your auto needs. By browsing our online catalog, surely you can find the ideal part you need for your model. Buy at our secure online store and get your selected item at a real reasonable price.