Chapter 12 Disc Brake System Components and Operation 177 Copyright by Goodheart-Willcox Co., Inc. Bleeder screw protective cap Bleeder screw Brake hose Backing plate Disc vents Heat being carried away in airstream Braking surface Cold air traveling through disc to help remove heat from braking Ventilated braking disc and hub assembly Caliper housing Cold air Direction of vehicle travel General Motors, Kyle Lee/Shutterstock.com Figure 12-1. A—Cross-sectional view of a typical single-piston, sliding (floating) disc brake assembly. Note the ventilated rotor (disc). B—Typical disc brake assembly. Outboard shoe and pad Ventilated rotor Piston seal Shoe retainer spring Caliper housing Cylinder bore Brake fluid inlet port Piston Boot Mounting bracket Rotor cooling fins Inboard shoe and pad A B Saab Figure 12-2. Brake rotors are either solid or ventilated. Note that with the ventilated rotor, air can pass between the braking surfaces to remove heat. This provides a more rapid cooling.