Wheel Cylinder Awheel cylinderis a component of a hydraulic drum brake system. It is located in each wheel and is usually positioned at the top of the wheel, above the shoes. Its function is to exert force onto the shoes so as to bring them into contact with the drum and stop the vehicle with friction. The wheel cylinders are usually connected to the shoes with small bird-beak shaped rods. Wheel cylinders were first invented by Bendix in 1958, 21 21 21. It is very similar to a slave cylinder and functions in much the same way, internally consisting of only a simple plunger. On older vehicles these may begin to leak and hinder the performance of the brakes, but are normally inexpensive and relatively easy to replace. The wheel cylinder consists of a cylinder that has two pistons, one on each side. Each piston has a rubber seal and a shaft that connects the piston with a brake shoe. When brake pressure is applied, the pistons are forced out pushing the shoes into contact with the drum. Some designs use two single piston wheel cylinders, one at the top of the drum and one at the bottom, each connected to one brake shoe. Wheel cylinders must be rebuilt or replaced if they show signs of leaking. Wheel cylinders used to be made of cast iron. However, they were more prone to rusting and aluminium is now the preferred material. It has a cylinder, two pistons, two rubber cups and a spring. The fluid presses against the pistons that move outward in the cylinder. When the piston come closer, the liquid is forced into the master cylinder, the spring between the two pistons holds the rubber cups in positions.

Master Cylinder In automotive engineering, themaster cylinderis a control device that converts force(commonly from a driver's foot) into hydraulic pressure. This device controlsslave cylinderslocated at the other end of the hydraulic system. As piston (s) move along the bore of the master cylinder, this movement is transferred through the hydraulic fluid, to result in a movement of the slave cylinder(s). The hydraulic pressure created by moving a piston (inside the bore of the master cylinder) toward the slave cylinder(s) compresses the fluid evenly, but by varying the comparative surface area of the master cylinder and each slave cylinder, one can vary the amount of force and displacement applied to each slave cylinder, relative to the amount of force and displacement applied to the master cylinder. Vehicle applications The most common vehicle uses of master cylinders are in brake and clutch systems. In brake systems, the operated devices are cylinders inside brake calipers and/or drum brakes; these cylinders may be called wheel cylinders or slave cylinders, and they push the brake pads towards a surface that rotates with the wheel (this surface is typically either a drum, or a disc, a.k.a. a rotor) until the stationary brake pad(s) create friction against that rotating surface (typically the rotating surface is metal or ceramic/carbon, for their ability to withstand heat and friction without wearing-down rapidly). In the clutch system, the device which the master cylinder operates is called the slave cylinder; it moves the throw out bearing until the high-friction material on the transmission's clutch disengages from the engine's metal (or ceramic/carbon) flywheel. For hydraulic brakes or clutches alike, flexible high-pressure hoses or inflexible hard-walled metal tubing may be used; but the flexible variety of tubing is needed for at least a short length adjacent to each wheel, whenever the wheel can move relative to the car's chassis (this is the case on any car with steering and other suspension movements; some drag racers and go-karts have no rear suspension, as the rear axle is welded to the chassis, and some antique cars also have no rear suspension movement). A reservoir above each master cylinder supplies the master cylinder with enough brake fluid to avoid air from entering the master cylinder (even the typical clutch uses brake fluid, but it may also be referred to as "clutch fluid" in a clutch application). Each piston in a master cylinder operates a brake circuit, and for modern light trucks and passenger cars, usually a brake circuit leads to a brake caliper or shoe on only two of the vehicle's wheels, and the other brake circuit provides brake pressure to slow down and stop the other two wheels. This is done in a diagonally split hydraulic system. If there is a hydraulic failure in the brake lines served by the master cylinder's secondary piston both pistons wil...