BMC Glossary of Terms
Please refer to the list below for brake industry terminology.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

- A -

ABS:

"Anti-lock Brake System." This brake system safety feature helps the driver maintain control during an emergency braking maneuver and avoids skidding while braking. ABS uses wheel speed sensors to determine if one or more wheels are trying to lock up.

 

aftermarket part:

A part that did not come with the original equipment, but was bought separately.

  

asbestos:

Asbestos provides friction, wear properties, and reinforcement in brakes. Due to health risks, manufacturers have used substitutes for asbestos. 

 

axle:

A spindle on which a wheel revolves. The axles house the front and rear braking system. (In Figure 1, the axle is indicated in purple.)

 
Figure 1. Axle (Front)

Back to Top

- B -

 balance:

Stability between the front and rear brakes.

 

BEEP®:

An acronym for "Brake Effectiveness Evaluation Procedure." This is a new test procedure for performing a single-ended dynamometer test that is similar to certain sections of the National Highway Safety Administration's (NHTSA's) Federal Motor Vehicle Safety Standards (FMVSS). Manufacturers voluntarily comply with these procedures for brake products.

 

bleeding:

Removal of overheated fluid and air bubbles from a brake system.

 

BMC:

Brake Manufacturers Council (www.brakecouncil.org) provides its members with current information relating to the brake industry and communicates with federal, state, and local government on the members' behalf.

 

brake drum:

A metal housing, shaped like an oversized jar lid and bolted to an axle and a vehicle wheel. Brake shoes covered with a friction material are forced against the circular inner surface of the drum to stop the rotating wheel.

 
Figure 2. Brake Drum

brake dust:

A fine powder residue created by the brake rotor or drum wearing away the brake lining.

 

brake lining:

Heat-resistant friction material that is pressed against a metal drum or disc to achieve braking force in the brake system. (See "brake pad" and "brake shoe.)

 

brake pad:

The disc brake part that needs to be replaced periodically. Pads consisting of friction material are bonded to metal plates (sometimes called disc brakes).

 

Brake Pad Partnership (BPP):

A group of government regulators, brake pad manufacturers, stormwater management agencies, and environmentalists charged with finding the impacts on the environment as a result of brake pad wear debris released from vehicles. (Find information on BPP at http://www.suscon.org/brakepad/index.asp.)

brake rotor:

The flat disk-like plates that connect the friction surface in a disc brake.

brake shoe:

A brake shoe consists of a steel shoe with the friction material or lining bonded to it. (See Figure 3.)

Figure 3. Brake Shoe

burnish:

The process of wearing-in brakes or using the brakes so that the contact between the friction material (shoe or pad) and its mating surface (rotor or drum) becomes stabilized.

Back to Top

- C -

caliper:

The assembly in disc brake that brings the pads to bear on the rotor. A brake caliper houses the brake pads and the hydraulically operated pistons. (The caliper is indicated in blue in Figure 4.)

Figure 4. Caliper

Back to Top

- D -

disc brake:

Most cars have disc brakes on the front wheels, and some have disc brakes on all four wheels. The main components of a disc brake are the brake pads, the caliper, and the rotor. The disc brake is the part of the brake system that actually stops the car. In a disc brake, the brake pads squeeze the rotor instead of the wheel. (See Figure 5.)

Figure 5. Disc Brakes

dynamometer:

Test apparatus used to measure brake system performance such as torque, fade, or wear in a laboratory environment.

Back to Top

- E -

 Back to Top

- F -

fade:

A temporary reduction of braking power (torque) due to overheating of the brake friction material.

 

friction material:

Material that is pushed against a disc by a shoe or caliper to generate friction.

  

FMVSS:

Federal Motor Vehicle Safety Standards (FMVSS) mandate the minimum safety performance of a new motor vehicle including brake performance, maximum stopping distances, and brake pedal effort. Find additional information at http://www.nhtsa.dot.gov.

Back to Top

- G -

Back to Top

- H -

Back to Top

- I -

Back to Top

- J -

Back to Top

- K -

Back to Top

- L -

Back to Top

- M -

master cylinder:

A cylinder containing a piston and hydraulic fluid, directly connected to a foot pedal (e.g., a brake master cylinder). It transmits pressure to the brake operating system.

Back to Top

- N -

NHTSA:

National Highway Traffic and Safety Administration (http://www.nhtsa.dot.gov). This organization establishes FMVSS performance requirements, and enforces conformance for new vehicles, including their brake systems.

Back to Top

- O -

 

OE:

Acronym for "original equipment." This is a part that a vehicle comes equipped with at the time the vehicle is assembled.

OEM:

Acronym for "original equipment manufacturer." It may refer to an "OE" or to a vehicle manufacturer.

Back to Top

- P -

Back to Top

- Q -

Back to Top

- R -

recovery (see fade):

After heavy braking, the return of the brake to a "normal" level. A measure of the ability of the friction material to perform after overheating.

Back to Top

- S -

SAE:

Society of Automotive Engineers (www.sae.org). This is an entity that shares and disseminates information and ideas for advancing the engineering of mobility systems. It consists of engineers, business executives, educators, and students.

SAE J2430:

Dynamometer Effectiveness Characterization Test for Passenger Car and Light Truck Brake Friction Products. An alternative single-ended dynamometer brake material test that is comparable to FMVSS tests.

squeal:

A high-pitched noise that indicates that brakes might need to be inspected for excessive wear.

semi-metallic:

High performance friction materials with significant amounts of metals that help prevent fade and squeal.

Back to Top

- T -

Back to Top

- U -

Back to Top

- V -

Back to Top

- W -

wear indicator:

The disc-shaped part of a disc brake assembly upon which the brake pads rest. (See Figure 6.)

Figure 6. Wear Indicator

Back to Top

- X -

Back to Top

- Y -

Back to Top

- Z -

Back to Top

Last updated May 4, 2004
Copyright © 2004 Brake Manufacturers Council (BMC)
All trademarks or product names mentioned herein are the property of their respective owners.