Chapter 12 Disc Brake System Components and Operation 183 Copyright by Goodheart-Willcox Co., Inc. Floating Caliper Operation One- or two-piston fl oating calipers operate in the same manner. As the brakes are applied, hydraulic pressure builds up in the cylinder bore behind the piston and their seals. Pressure forces the piston outward. When the piston moves enough to force the inner brake pad into contact with the rotor, resistance to outward piston movement is increased. It now becomes easier for hydraulic pressure to push the cali- per backward instead of pushing further on the inner pad. Th e caliper then “fl oats” inward, bringing the outer brake pad into contact with the rotor. Pad pressure is then equal on both sides, which slows the rotor. When the brakes are released, the outer seal returns the piston to its normal position. Th is movement is very slight as it is done by the seal trying to straighten itself, which tends to draw the piston in. As the piston returns to its unapplied position, the pads are moved away from the Spindle anchor Caliper assembly Bleeder screw Outboard pad Ventilated rotor A Sleeve Locating pin Insulator Caliper B Ford Figure 12-12. A— A single-piston, floating caliper assembly. B—Locating pins, sleeves, and insulators allow the caliper to slide (travel) from side to side. Retainer pin bolt Sleeve Clip Cushion Cast mounting bracket Mounting bracket bolts Bushings Bleeder screw Cushion Clip Machined ways TRW Inc. Figure 12-13. An exploded view of a floating caliper assembly using only one retainer pin bolt and machined ways to secure it to the cast mounting bracket. Integral spindle and anchor plate Caliper assembly Combination caliper locating and attaching pin Ford Figure 12-14. A single-piston, sliding caliper assembly. This caliper bolts onto an integral cast extension of the spindle.