Calipers and Wheel Cylinders

Calipers and wheel cylinders are the main hydraulic devices used to apply the brakes in the braking system by the use of hydraulics or pressurized brake fluid sent from the master cylinder. Calipers are used for disc brakes, while wheel cylinders are used for drum brakes.

Three types of braking systems include four-wheel disc brakes (which do not include wheel cylinders), front disc and rear drum system (which include calipers in the front and wheel cylinders in the rear), and some older vehicles consist of a four-wheel drum system (which does not include calipers). However, four-wheel drum brake systems were used on some older model vehicles, but today they are no longer being manufactured.

Calipers and wheel cylinders both contain pistons that are actuated when the brakes are applied. However, calipers have several different styles that include either one, two, four, or six pistons, while wheel cylinders are only equipped with two pistons.

Calipers can be a fixed design or can be a floating and sliding design.

Fixed calipers are generally larger and heavier and the body of the caliper tends to be manufactured in two halves. These fixed calipers can consist of two, four, or even six pistons inside the caliper’s bore.

Floating and sliding calipers on the other hand are typically smaller and only include one or two pistons in their bore. These calipers are set apart from a fixed caliper by the use of guide pins or sliders and the use of additional bushings.

Single piston rear calipers may also provide an internal mechanism to actuate the parking brakes.

Wheel cylinders on the other hand have just two pistons and an internal spring that presses up against each piston when the cylinder detects brake fluid pressure.

View our brake inspection page to see if your calipers are in need of replacement. The following steps are specific procedures that should be followed when attempting to remove and install various caliper and wheel cylinder designs.

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