Wheel cylinders are a component found in drum brake systems.
Also known as a slave cylinder, the wheel cylinder is a hydraulic
cylinder that amplifies the pressure in the master cylinder to evenly operate a drum
brake. There may be one or more per brake. Wheel cylinders
contain hydraulic fluid and a piston that forces the brake shoe against the brake drums when the brake pedal
A wheel cylinder is mounted on the backing plate near the
top of the brake drum assembly. It consists of an outer metal
housing and a set of internal components. The brake line connects
to an inlet fitting.
When the brake pedal is pressed down, brake fluid fills the
wheel cylinder's inner chamber. When sufficient hydraulic
pressure has built up, brake fluid forces the pistons in the
cylinder outward, forcing the brake shoes against the spinning
brake drum. Friction between the brake shoes and the inside
drum surface eventually slows or stops the wheel from turning.
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