Brake pad

With a brake pad (also known as brake block ) refers to a device for vehicles to reduce the speed of the vehicle, the kinetic energy is converted by the friction against a drum or disc to heat. Also on brakes moving parts of stationary machine pads are used.

The widespread notion brake pad or brake shoe means the carrier components of the brake pads and the bike or the railroad. With disc brakes of the material is glued on the support, wherein the drum brake it is glued or riveted to the brake shoe.

Composition

The standard brake pads made ​​of the materials:

• Carrier plate made of steel or cast iron. However, there are always efforts for the sake of weight savings to bring plastic support plates are used. Rail pads sometimes have no backing plate, but pressed plates with which the block is inserted into a holder.
• Friction means, among other things, the fact Antimony and copper, formerly lead and asbestos; In addition, heavy spar ( barium sulfate), the binding resin which is carbonized in the course of production under the influence of heat and all of the particles to each other; In addition, substances which impart the desired properties to the brake pad, such as metals (copper, brass, iron, cast iron powder or fibers), mineral fibers, the sulfides of iron, copper, antimony, zinc, tin, molybdenum
• Sometimes when brake pads Geräuschdämmplatte a metal or plastic

Reibmittelkategorien

International four different Reibmittelkategorien be called. The differences may be blurred. In particular, the term " Ceramic" is broad. Most manufacturers have more friction means concoctions, whose composition is most closely guarded secret. Exotic products such as the resin of the cashew nut, but also aramids such as Kevlar ® or Twaron ® by DuPont Teijin Aramid used.

Semi- Metallic

Friction means in the category " Semi- metallic " contain 30 to 65% of metal (steel, iron, copper, brass, etc. ) is mixed with graphite, fillers, and binders. These films have a reputation for low costs with a long shelf life and a good hot braking performance, but also a high wear of the brake disc and the susceptibility to squeaks. Principal market for such pads was previously North America, where they are but increasingly replaced by ceramic tiles.

Organic

Friction means in the category " Organic" (sometimes called "non -asbestos organic " or NAO ) are made of fibers which can be obtained from glass, rubber, carbon fiber or Kevlar ® and Twaron ®. They also consist of fillers and temperature- resistant synthetic or natural resins. These deposits are considered to be softer, quieter, but they also have the reputation of a faster wear and the development of more brake dust. They are developing, especially after an elevated temperature exposure, a poorer friction characteristics. Principal market for such pads is Japan and the United States.

Low- Metallic

Friction means this category consist of the aforementioned organic matter, mixed with a proportion of 10 to 30% of metal, usually copper or steel. These films have the reputation of a better hot braking performance, especially at high speeds. On the negative side brake dust and Quietschneigung be called. Principal market for such deposits is Europe.

Ceramic

Friction means the ceramic category are relatively new. Ceramic tiles were first used in 1985 by vehicle manufacturers. This friction means consist of ceramic fibers, fillers, binders, and possibly small amounts of metal. These deposits are typically lighter, quieter, but also more expensive than other coverings. When using ceramic tiles of the disc wear is considered to be low. Main markets of these coverings are North America and Japan. Although the term "Ceramic" has received wide use, it is not regarded by experts as a generic term for a friction means. Each coating comprising ceramic ingredients can be referred to as " ceramics ." It may well be that a covering which is sold in Europe as a "low- metallic", is marketed in the U.S. as " ceramic".

Sports and luxury cars sometimes also have pads made ​​of carbon fiber reinforced silicon carbide or traces of clay.

Asbestos

A considerable amount of asbestos was ( to 42 % share) attached Prior to 1990, which has since been banned in the EU. The increased concentration of asbestos can, however, still in areas where much braked ( intersections, highway exits, runways, railway stations ), demonstrate. The manufacture, distribution and installation of brake linings containing asbestos is banned in the EU since the introduction of Asbestos Regulation ( amended 1989).

Requirements for brake pads

The brake lining should:

• Possible, an equal number have friction ( brake fading due to overheating )
• Temperature resistant (up to 800 ° C) to prevent the "glazing " and
• Be mechanically robust.

New brake pads have their full braking effect only after a certain break-in period. During this phase, the coating surface to the surface of the disc or drum is similar to until a uniform contact pattern developed. Within this phase, the material at the contact surface changed to the disc / drum. It forms friction carbon. Only then is the optimal combination of the friction pair ( brake pad or disc, brake pad or drum) is thus reached the maximum deceleration during braking.

Wear

During braking, the brake pad rubs off on the brake disc, therefore brake pads are wear parts. Brake pads are changed several times during the life of a vehicle, more often than the brake disk. Brake pads (and discs ), only on the entire axis and not be changed individually. Since adjust the brake pads to the brake discs by abrasion, the brake pads must be replaced when a brake disc change.

As in previous brake pads had wear indicators, which gave an indication of when the coating was worn. This wear indicator or so-called warning contact was invented in the late 1970s from which Israel had emigrated to Germany automotive electrician Yigal Bar - Yoav. He also developed today known function of the warning contact, indicative of the state of the pad prior to the complete wear. Bar - Yoav made ​​thereby Ohm's law advantage. The lower surface is provided, the larger the measured electrical resistance. Simpler and more common wear sensors have inserted a wire in the last few millimeters of the brake lining; as soon as the brake is so much worn that the wire touches the brake disc, produced ground contact. Thus lit or flickers a warning light in the vehicle. The production of modern, high-quality wear indicators must, as is the production of the flooring, access to most heat resistant materials. Limits at the operating temperature of the pads need to be maintained over the entire period covered by the set of the thin set into the paving material cable loop. To this end, manufacturers, whose sensors meet the prescribed accordingly claims of the auto industry, the latest thermosets, their heat resistance of even the pad equals.

Some brake pads have audible wear warning. It is mounted in the form of a flat bent metal plate at the rear of the pads, and is made with a decreasing coating thickness on the friction of the pads to vibrate. Through this vibration then creates a high, squeaky sound.

As a contribution to particulate air pollution brake pads are again advised since the abolition of asbestos in the criticism and investigation object.

Since brake pads are often exchanged as part of a vehicle service, are there a large market with a variety of manufacturers. In the EU may only brake pads, which correspond to the ECE - R 90, are used in the space shared vehicle. The regulation ECE R 90 specifies inter alia the following properties:

• The same coefficient of friction as original coverings of the vehicle manufacturer ( deviations up to ± 15 % allowed)
• Compression, shear strength and material hardness
• Testing for speed sensitivity
• Asbestos freedom
• An approval mark shall be permanently identified on the replacement part. It consists of a circle in which there is the letter " E" followed by the distinguishing number of the country which has granted approval and the name " 90 R" followed by a hyphen and an approval number.
• The packaging of the pads must be bonded / sealed to recognize previous opening clear.
• On the packaging of vehicles registered for the topping must be listed.
• Each packaging must assembly instructions in one of the official languages ​​of the ECE and the language of the country in which they are sold, accompanied.

The aim of this scheme is that replica brake pads meet at least some minimum requirements. For automotive parts high price differences between original parts and replica market exist and therefore could not control for these customers doubts as to the quality or safety arise. Especially webshops and working in online auctions worldwide automotive parts dealer therefore particularly emphasized that their products have this e- ID and praise them as a sign of quality.

Supplier of brake pads for the German replica market, the ECE -R correspond to 90 are, for example Becorit, Bremskerl, Bosch, Brembo, Continental AG (ATE, Barum ), EBC, euro brake band ( Beral ), Federal- Mogul ( Ferodo ), Honeywell ( Jurid, Bendix ), TMD Friction ( Pagid, Textar, Mintex, Don ), TRW / Lucas, PEX Automotive Group. The well-known vehicle manufacturers produce no way even brake pads, but let this produce of brake pad manufacturers according to their own specifications.

Cataloging

Brake pads are cataloged according to classification systems. The most widely used classification system in Europe is also used worldwide WVA numbering system.