A piston is a cylindrical device that transmits hydraulic or pneumatic force within a process. A brake piston, therefore, transmits force provided by hydraulically- or pneumatically-driven brakes. When a brake lever is pushed, the gas drives the piston to rotate, which allows the vehicle to brake.
Significance
The rotation of a brake piston equates to force being exerted on a vehicle's braking system. Many vehicles have either hydraulic or pneumatic brake systems, which means they are driven by gas or air, respectively. When a brake lever is pressed or squeezed, it exerts force on the piston to rotate.
Function
The rotation of the piston allows brake fluid to be released into the pressure chamber, and, ultimately, through the entire hydraulic system of the vehicle. When the brake pistons rotate, it applies force to the brake pads, causing them to be pushed against the rotation of the piston. The friction between the pads and the rotor generates a braking torque, which slows the vehicle.
Repair
Another action referred to as brake piston rotation sometimes occurs during the installation of new brake pads. Many mechanics and auto repair shops have brake piston rotation tools. These are specialized tools designed to manually rotate the park brake piston into the brake caliper when replacing brake pads on vehicles.
