249:- Composed of clay and porcelain bonded to copper flakes and filaments, these are a good compromise between the durability of the metal pads, grip and fade resistance of the synthetic variety. Their principal drawback, however, is that unlike the previous three types, despite the presence of the copper (which has a high thermal conductivity), ceramic pads generally do not dissipate heat well, which can eventually cause the pads or other components of the braking system to warp. However, because the ceramic materials cause the braking sound to be elevated beyond that of human hearing, they seem exceptionally quiet.
77:
usually be replaced regularly (depending on pad material). Most brake pads are equipped with a method of alerting the driver when this needs to be done. A common technique is manufacturing a small central groove whose eventual disappearance by wear indicates the end of a pad's service life. Other methods include placing a thin strip of soft metal in a groove, such that when exposed (due to wear) the brakes squeal audibly. A soft metal wear tab can also be embedded in the pad material that closes an
146:
469:(NBS) started testing of brake material in the US in 1920. The testing setup was then shared with manufacturers who wanted them so that they could begin to test their own products. Over time the NBS continued to develop new instruments and procedures for testing pads and lining, and these standards eventually became the standards for the American Engineering Standards Committee's Safety Code for Brakes and Brake Testing.
237:- synthetics mixed with varying proportions of flaked metals. These are harder than non-metallic pads, more fade-resistant and longer lasting, but at the cost of increased wear to the rotor/drum which then must be replaced sooner. They also require more actuating force than non-metallic pads in order to generate braking torque.
130:" caused by the overheating of brake pads, and are also able to recover quickly from immersion (wet brakes are less effective). Unlike a drum brake, a disc brake has no self-servo effect—the braking force is always proportional to the pressure applied on the braking pedal lever. However many disc brake systems have
472:
SAE J661 testing is used to determine the friction of different brake pad materials by testing a 1 inch (25 mm) square liner with a brake drum. This testing yields values for both hot and cold coefficients of friction, which are then paired with letter designations. The table below outlines what
367:
There are environmental factors that govern the selection of brake pad materials. For example, the bill SSB 6557 adopted in
Washington State in 2010 limits the amount of copper that is allowed to be used in friction materials, to be eventually phased out to trace amounts, due to the negative impact
553:
The cataloguing system used in North
America, and recognized around the world, is the standardized part numbering system for brakes and clutch facings issued by the Friction Materials Standards Institute (FMSI). FMSI's mission is to, "Maintain and enhance this standardized part numbering system for
153:
There are numerous types of brake pads, depending on the intended use of the vehicle, from very soft and aggressive (such as racing applications) to harder, more durable and less aggressive compounds. Most vehicle manufacturers recommend a specific kind of brake pad for their vehicle, but compounds
208:
hazards of asbestos eventually started to become apparent, other materials had to be found. Asbestos brake pads have largely been replaced by non-asbestos organic (NAO) materials in first world countries. Today, brake pad materials are classified into one of four principal categories, as follows:
105:
Grand Prix of
Endurance race. The success of the Jaguar is commonly attributed to the car’s disc brakes, which allowed the drivers to approach turns faster and brake later than their opponents, which ultimately led to its victory. As late as 1963 the majority of automobiles using disc brakes were
207:
was added as a common ingredient to brake pads post-WWI, as car speeds began to increase, because research showed that its properties allowed it to absorb the heat (which can reach 500 °F) while still providing the friction necessary to stop a vehicle. However, as the serious health-related
76:
upright. Racing calipers, however, can utilize up to six pads, with varying frictional properties in a staggered pattern for optimum performance. Depending on the properties of the material, the weight of the vehicle and the speeds it is driven at, disc wear rates may vary. The brake pads must
200:
Another material requirement that is considered is how compressible the brake pads are; if they are too compressible then brake travel or brake booster fluid displacement can be excessive. Brake pad material must also be porous to minimize the effect water has on the friction coefficient.
243:- these pads are used only in racing vehicles, and are composed of sintered steel without any synthetic additives. They are very long-lasting, but require more force to slow a vehicle while wearing off the rotors faster. They also tend to be very loud.
371:
Vehicles have different braking requirements. Friction materials offer application-specific formulas and designs. Brake pads with a higher coefficient of friction provide good braking with less brake pedal pressure requirement, but tend to lose
69:, it transfers small amounts of its friction material onto the disc, leaving a dull grey coating on it. The brake pad and disc (now both having the friction material), then "stick" to each other, providing the friction that stops the vehicle.
154:
can be changed (by either buying a different make of pad or upgrading to a performance pad in a manufacturer's range) according to personal tastes and driving styles. Care must always be taken when buying non-standard brake pads as the
368:
of high copper levels on aquatic life. For its substitution, different material combinations have been developed, though no direct replacement is available yet. Other materials, such as compounds made with antimony, are being studied.
384:
Brake pads should be checked at least every 5,000 miles for excessive or uneven wear. Although brake pad wear is unique to each vehicle, it is generally recommended that brake pads be replaced every 50,000 miles.
101:. Once disc brake technology improved, brake performance quickly surpassed that of drum brakes. The performance difference was most noticeably exhibited in 1953 when a Jaguar outfitted with brake pads won the
187:
of modern brake pads should be low enough prevent locking of the wheels but high enough to provide sufficient stopping power. Friction coefficients are typically between 0.3 and 0.5 for brake pad materials.
193:
The ability of the material to provide smooth and even contact with the rotor or drum, instead of a material that breaks off in chunks or causes pits, dents, or other damage to the surface in contact.
376:
at higher temperatures. Brake pads with a smaller and constant coefficient of friction do not lose efficiency at higher temperatures and are stable, but require higher brake pedal pressure.
416:
Faulty brake caliper, restriction in hydraulic system, brake pad lining(s) contaminated with oil or brake fluid, brake pads not replaced in pairs, brake pad not fitted correctly,
388:
Malfunctions with brake pads can have many effects on the performance of a vehicle. The following chart outlines some common issues that can be caused by brake pad malfunctions:
473:
letter goes with each range for the coefficient of friction. An example of the designation would be "GD", where "G" is the normal coefficient, while the "D" represents heated.
72:
In disc brakes, there are usually two brake pads per disc rotor, they both function together. These are held in place and actuated by a caliper affixed to the wheel hub or
174:
The material's ability to resist brake fade, caused by an increase in temperature the material will experience from the conversion of kinetic energy into thermal energy.
37:
used in automotive and other applications. Brake pads are composed of steel backing plates with friction material bound to the surface that faces the disc brake rotors.
180:
The ability to recover quickly from increased temperature or moisture, and exhibit approximately the same friction levels at any point in the drying or cooling process.
426:
brake fluid; Overheated brake pad linings, worn brake pads, faulty master cylinder, brake fluid leak, air in brake fluid, misadjusted brake shoes, boiling brake fluid
65:
applied, the caliper clamps or squeezes the two pads together onto the spinning rotor to slow and stop the vehicle. When a brake pad heats up due to contact with the
106:
European made, with
American cars adopting the technology in the late 1960s after the invention of fixed calipers that made installation cheaper and more compact.
158:
ranges may vary, such as performance pads not braking efficiently when cold or standard pads fading under hard driving. In cars that suffer from excessive
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The ability to resist wear due to friction, but not to the extent that rotor wear occurs more quickly than brake material is sacrificed.
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783:
408:
Worn brake pads, contaminated brake fluid, faulty brake caliper, faulty master cylinder, loss of vacuum, loss of brake fluid
97:
in 1902. However, due to high cost and inefficiencies compared to drum brakes they were not commonly implemented until after
446:
Extremely worn brake pads, brake pad(s) not fitted correctly, faulty or missing brake pad shim, brake pad wear indicator
215:- these are made from a combination of various synthetic substances bonded into a composite, principally in the form of
435:
Incorrect brake pad linings; Greasy brake pad linings, faulty proportioning valve, misadjusted master cylinder pushrod
937:
737:
682:
177:
The effects of moisture on brake fade. All brakes are designed to withstand at least temporary exposure to water.
546:
There are different systems for the cataloguing of brake pads. The most frequently used system in Europe is the
272:
as a cheap and less energy-intensive binding agent. The table below outlines the make up of a common brake pad.
899:
863:
823:
644:
170:
The most important characteristics that are considered when selecting a brake pad material are as follows:
1048:"Virtue via Association: The National Bureau of Standards, Automobiles, and Political Economy, 1919–1940"
983:
930:
Advanced
Composite Materials for Automotive Applications : Structural Integrity and Crashworthiness
995:
17:
1087:
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can serve as a friction material as well as binding agent. Another friction material commonly used is
1007:
Rampin, Ilaria; Zanon, Matteo; Echeberria, Jon; Loreto, Antonio Di; Martinez, Anemaite (2014-05-19).
253:
1029:
730:
The science of
Formula 1 design : expert analysis of the anatomy of the modern Grand Prix car
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231:. They are gentle on rotors, but produce a fair amount of dust, thus having a short service life.
94:
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162:, the problem can be minimized by installing better quality and more aggressive brake pads.
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Disc brake pads are easier to inspect and replace than drum brake friction lining.
78:
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Contaminated rotors or pads, warped rotors, out of round drums, ABS activation
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The ability to apply appropriate frictional force while also operating quietly.
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818:. Society of Automotive Engineers. (3rd ed.). Warrendale, PA: SAE.
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547:
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34:
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Today's
Technician: Automotive Brake Systems Classroom and Shop Manual
892:
Automotive chassis and body: construction, operation, and maintenance
216:
1009:"Development of copper-free low steel brake pads for passenger cars"
984:
Forschungsprojekt Cobra - Die Bremse der
Zukunft besteht aus Zement
261:
204:
81:
when the brake pad wears thin, lighting a dashboard warning light.
61:
with their friction surfaces facing the rotor. When the brakes are
54:
858:(2nd ed.). Warrendale, Pa.: Society of Automotive Engineers.
732:(3rd ed.). Sparkford, NR Yeovil, Somerset, U.K.: Haynes Pub.
996:
Limiting the use of certain substances in brake friction material
269:
220:
89:
The concept of brake pads or disc brakes as an alternative to
813:
1091:
1006:
675:
The evolution of automotive technology : a handbook
620:
Henderson, Bob; Haynes, John H. (1994). "Disc Brakes".
134:("Brake Booster") to reduce the driver's pedal effort.
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268:. An Italian producer is conducting research to use
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554:all on highway vehicles in use in North America."
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122:offer better stopping performance as compared to
93:had been around at least as early as a patent by
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424:Brake pad lining(s) soaked with water, oil, or
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149:A set of pads for high-performance disk brakes
479:Letter Designation for Friction Coefficients
440:Noisy braking (grinding or screeching sounds
402:Braking requires an abnormal amount of force
639:. Spurr, R. T. Bristol, England: A. Hilger.
709:) CS1 maint: multiple names: authors list (
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894:(4th ed.). New York: McGraw-Hill.
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1129:
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814:Nunney, M. J. (Malcolm James) (1998).
624:. Haynes North America. pp. 1–20.
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57:. Two brake pads are contained in the
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126:. They provide better resistance to "
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637:A technical history of the motor car
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622:The Haynes Automotive Brake Manual
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986:, February 2015 in: Ingenieur.de
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380:Maintenance and Troubleshooting
890:Crouse, William Harry (1971).
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1142:Vehicle braking technologies
677:. Warrendale, Pennsylvania.
562:A type of brake pad used on
467:National Bureau of Standards
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7:
772:Cliff Owen (21 June 2010).
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10:
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928:Elmarakbi, Ahmed. (2013).
84:
854:Limpert, Rudolf. (1999).
728:Tremayne, David. (2009).
673:Mom, Gijs, 1949- (2014).
421:Poor braking performance
254:Phenol formaldehyde resin
1052:Enterprise & Society
451:Vibration under braking
256:is frequently used as a
241:Fully metallic materials
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27:Component of disc brakes
856:Brake design and safety
635:Newcomb, T. P. (1989).
235:Semi-metallic materials
45:Brake pads convert the
1088:"WVA numbering system"
1024:Cite journal requires
213:Non-metallic materials
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969:Entry on brake pads (
816:Automotive technology
596:Electromagnetic brake
156:operating temperature
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115:Disc brake advantages
1046:Vinsel, Lee (2016).
586:Brake wear indicator
548:WVA numbering system
461:Testing of Materials
185:friction coefficient
1065:10.1017/eso.2015.61
558:Cartridge brake pad
103:24 Hours of Le Mans
33:are a component of
932:. Hoboken: Wiley.
601:List of auto parts
432:Sensitive braking
266:zirconium silicate
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120:Disc brakes
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607:References
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564:rim brakes
374:efficiency
160:brake fade
128:brake fade
110:Technology
74:suspension
31:Brake pads
18:Brake pads
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