Construction and principle of operation of the disc brake

Force exerted by the driver on the pedal, multiplied by an assistive device, creates hydraulic fluid pressure in the pump, pressing the blocks with friction linings through pistons to the disc rotating with the wheel. The disc is cast from grey cast iron. It is a decisive element for the reliability of the brake operation, therefore, it is subject to meticulous control during production. In addition to uniform discs, discs with internal cooling are encountered – ribbed, with radial heat dissipation ducts and axial vents. In sports cars, the discs can be made of ceramic materials (e.g.. Porsche) or carbon (F1 cars). On brakes with fixed piston caliper housing (two or four) act on the shield independently from both sides. This solution is effective, but expensive, it also takes up a lot of space. The popularization of front suspensions with a negative stagger radius caused the development of a structure with a movable yoke, and for years 70. with movable ("floating") clamp housing. They have a more compact structure. Fit in small diameter wheels, are easy to manufacture and maintain. Piston (pistons) of the caliper is located on the inside of the brake disc, and its movement forces the housing to move due to the reaction force.
Friction linings, whose most important parameters are high, temperature-independent coefficient of friction and high abrasion resistance possible, is made of a mixture of lint or metallic powder with a synthetic resin filler. On the one hand, the future of brakes is new, faster ways to start them, e.g.. by electric means, on the other hand, a further increase in effectiveness, e.g.. by replacing the existing dial with a ring, with which blocks with cylindrical working surfaces work. Both solutions remain in intensive trials for the time being.. In more expensive cars (e.g.. Audi) however, disc brakes with an internal caliper are used, with a larger radius of action and higher efficiency.