Ch. 43: Brake System Tech

anti-rattle clip

A clip that snaps onto a brake pad to keep it from vibrating and rattling.

bleeder screw

A screw that allows air to be removed from a hydraulic brake system. When the screw is loosened, hydraulic pressure can be used to force fluid and air out of the system.

brake backing plate

A metal plate that holds the shoes, springs, wheel cylinder, and other parts inside the brake drum. It also helps keep road dirt and water off the brakes.

brake booster

A vacuum, electric, or power steering operated device that assists brake pedal application.

brake caliper

A disc brake component that forms the cylinder and houses the piston and brake pads. It produces the clamping action on the rotating disc to stop the vehicle.

brake disc

A rotor that uses friction from the brake pads to slow or stop wheel rotation. It is normally made of cast iron. It is also referred to as a rotor or brake rotor.

brake disc runout

The amount of side-to-side movement measured near the outer edge of a brake disc's friction surface.

brake drum

A friction surface against which the brake shoe linings rub when applied to slow or stop wheel rotation.

brake hose

A hose that transfers fluid pressure from the master cylinder to the wheel brake assemblies.

brake line

A metal tubing and rubber hose for transmitting pressure to wheel brake assemblies.

brake pad

A friction unit that is pushed against the disc by the action of the master cylinder, caliper cylinder, and piston.

brake pedal assembly

A foot-operated lever for actuating the master cylinder and power booster.

brake shoe

A friction unit that is pushed against the rotating brake drum by the action of the hydraulic wheel cylinder.

brake warning light switch

A pressure-sensitive switch that warns a driver of a pressure loss on one side of a hydraulic brake system. It is also referred to as a pressure differential valve.

braking ratio

A comparison of the front wheel to rear wheel braking effort.

caliper

A brake assembly part that holds a hydraulic cylinder, piston, seals, and brake pads.

diagonally split brake system

A corner-to-corner brake system that has each master cylinder piston operating the brake assemblies on opposite corners of the vehicle.

disc brake assembly

A brake assembly that consists of a caliper, brake pads, a disc, and related hardware, such as the bolts, clips, and springs.

disc brake pad

A steel plate to which linings are riveted or bonded. Each caliper has an inner and outer brake pad that fits inside the hydraulic brake caliper.

drum brake assembly

A brake assembly consisting of a backing plate, a wheel cylinder, brake shoes and linings, retracting springs, hold-down springs, a brake drum, and an automatic adjusting mechanism.

dual master cylinder

A master cylinder that has two separate hydraulic pistons and two fluid reservoirs.

electric parking brake

A parking brake system that uses a dash-mounted switch and an electric servo motor to apply the rear brake mechanically.

fixed caliper

A brake caliper that does not move during braking because it is mounted rigidly to the spindle.

floating caliper

A caliper that can move or 'float' back and forth in relation to the rotor.

hybrid brake

A form of regenerative braking. This electric braking system works with the conventional hydraulic brakes to slow the vehicle, while at the same time generating electricity to recharge the vehicle's HV battery.

hydraulic brake

A type of brake that uses fluid pressure to activate braking.

longitudinally split brake system

A front to rear brake system in which one master cylinder piston operates the front wheel brake assemblies and the other operates the rear brake assemblies.

master cylinder

A hydraulic piston-type pump that stores brake fluid and develops pressure for a brake system.

pad-wear sensor

A metal tab on the brake pad that informs the driver of worn brake pad linings. The wear sensor tab emits a loud squeal or squeak when it scrapes against the brake disc.

parking brake

A device that provides a mechanical means (cable and levers) or electrical means (servo motor) of applying the rear brakes.

piston boot

Rubber covering that keeps road dirt and water off the caliper piston and the wall of the cylinder.

piston seal

Seal in a brake caliper that prevents pressure leakage between the piston and cylinder.

power brake

A brake system that uses a booster and either engine vacuum, electric pump, or hydraulic pressure to assist brake pedal application.

primary brake shoe

The front brake shoe that normally has a slightly shorter lining than the secondary shoe.

rotor

A disc that uses friction from the brake pads to slow or stop wheel rotation. It is normally made of cast iron. It is also referred to as a brake disc.

secondary brake shoe

The rear brake shoe that has the largest lining surface area.

sliding caliper

The sliding caliper disc brake is a one-piston caliper that is mounted in slots machined in the caliper adapter. The caliper is free to slide sideways in the slots or grooves as the linings wear.

vacuum booster

Uses engine vacuum or vacuum created by an auxiliary pump to help apply the brake pedal.

wheel cylinder

Acts as the power piston, moving the friction linings into contact with the rotating drums or discs.