A brake caliper is a major component of a disc brake system in a vehicle. Attached to each wheel is a thick, heavy metal disc called a brake rotor (the “disc” in disc brakes) that spins along with the wheel when your vehicle is moving. Sandwiched around the rotor is a pair of brake pads that have the job of grabbing hold of the rotor when you want to slow down or stop. The brake caliper acts as a hydraulic clamping device that suspends the brake pads in place and squeezes them together when you press on the brake pedal.
Inside the caliper resides one or more metal pistons that move in response to hydraulic pressure. When you step on the brake pedal, the master cylinder (pump) exerts pressure on the hydraulic brake fluid inside a network of tubes that lead to the calipers. The fluid, in turn, exerts pressure on the caliper piston(s), which squeezes together the brake pads against the rotor.
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