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What Is the Function of Brake Calipers?

Updated March 23, 2017

The brakes are the most important safety feature of any vehicle, and the calipers are one of the most important components of the braking system. They apply the force necessary to slow and stop your vehicle. Keeping them in good repair is essential to safe operation. If the calipers aren't working, your car will just keep on going---even when you don't want it to.

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Calipers are an essential part of a disc-braking system. They are small, boxy, rectangular devices that are contained within the wheel housing. They are set close to either side of the rotary metal disc that is attached to your wheels. They are operated by a hydraulic system that uses brake fluid as a medium to transfer the pressure of a depressed brake pedal directly to the calipers.


The standard brake caliper contains metal plates on both the outside and inside face of the rotor. The plates are faced with brake pads, which are the point of contact between the calipers and the rotors. When you depress the brake pedal, brake fluid flows through a master cylinder, which is linked to a piston housed within the calipers. The piston presses against the pads and forces them against the rotors. The action of friction slows down the rotor and the wheel.


Disc brakes came on the commercial vehicle market in the 1950s. They represented an improvement over older drum brakes, which were prone to overheating and deteriorating performance over a short amount of time. Nearly all cars and trucks known have front-end disc brakes; some less expensive models still use drum brakes on the rear axle.

Floating and Fixed

Floating calipers have their hydraulic pistons on the inboard side of the rotor; they move in and out as the brake pedal is depressed. Fixed calipers have their pistons set up on both sides of the rotor and apply pressure directly from both sides, allowing them smoother operation and more braking power; the floaters, however, are less tolerant of any defects or warping of the rotors.


The brake pads contained within the calipers gradually wear from the constant friction, pressure and high temperature. Worn pads provide less reliable braking power and begin to create noise. When the driver begins to hear squeaking and squealing, the pads should be checked and replaced. The rotors of a disc-brake system should be regularly checked for wear and defects.

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About the Author

Tom Streissguth

Founder/president of the innovative reference publisher The Archive LLC, Tom Streissguth has been a self-employed business owner, independent bookseller and freelance author in the school/library market. Holding a bachelor's degree from Yale, Streissguth has published more than 100 works of history, biography, current affairs and geography for young readers.

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