Differential pulley the system becomes a simple "gun tackle" with a mechanical advantage of 2. The same principle is used in a differential windlass, where the connected pulleys are replaced by winches. In the above graphic, the four segments of the chain are labelled W, X, Y and Z. The magnitudes of their corresponding forces are "F", "F", "F" and "F", respectively. Assuming that the chain is massless, "F" = 0 because segment X is not supporting any weight. Taking the system at equilibrium, "F" and "F" are equal — if they were not, the lower pulley would freely turn until they
Brake shoe Brake shoe A brake shoe is the part of a braking system which carries the brake lining in the drum brakes used on automobiles, or the brake block in train brakes and bicycle brakes. The brake shoe carries the brake lining, which is riveted or glued to the shoe. When the brake is applied, the shoe moves and presses the lining against the inside of the drum. The friction between lining and drum provides the braking effort. Energy is dissipated as heat. Modern cars have disc brakes all round, or discs at the front and drums at the rear. An