Brake Caliper: Description and Operation

Fig. 1 Girlock single piston caliper exploded view:

This caliper, Fig. 1, has a single piston in an aluminum housing suspended in the mounting bracket on two slide pins. Hydraulic pressure, created by applying force to the brake pedal, acts equally against the piston and the bottom of the caliper bore to move the piston outward and to slide the caliper inward resulting in a clamping action on the brake rotor.