Brake lining
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Brake linings are the consumable surfaces in brake systems, such as drum brakes and disc brakes used in transport vehicles.
History
Brake linings were invented by
Structure and function
Brake linings are composed of a relatively soft but tough and heat-resistant material with a high
Using a typical bicycle brake as an example, the backing would be the metal shell which provides mechanical support, and the lining would be the rubbery portion which contacts the rims when the brakes are applied. In most modern vehicular applications the system is conceptually identical, except the rims would be replaced with solid steel (or sometimes exotic metal) disc. Furthermore, a metal tang is usually incorporated into the pad assembly. The tang contacts the rotors when the linings are worn out, causing an annoying noise designed to alert the motorist that brake servicing is required.
Since the lining is the portion of the braking system which converts the vehicle's kinetic energy into heat, the lining must be capable of surviving high temperatures without excessive wear (leading to frequent replacement) or outgassing (which causes brake fade, a decrease in the stopping power of the brake).
Due to its efficacy,
Maintenance
When the lining is worn out, the backing or rivets will contact the rotors or drums during braking, often causing damage requiring re-machining or replacement of the drums or rotors. An annoying squeal caused by the warning tang is designed as a typical audible alert that the pads need to be replaced; some vehicles may also have electrical brake wear indicators. If the squeal or wear indicator is ignored for too long, drum or rotor damage (usually accompanied by an unpleasant grinding sound or sensation) together with degraded braking capacity will be the result.
The brake lining may also become contaminated by oil or leaked brake fluid. Typical symptoms will be brake chatter, where the pads vibrate as the lining grabs and releases the rotor's surface. The solution is to repair and clean the source of the contamination, replace the damaged pads and possibly also have the rotors re-skimmed or replaced if they are damaged.
In the automotive repair industry, consumers can purchase brake pads with a lifetime warranty.[citation needed] These pads use a much harder lining than traditional brake pads and tend to cause excessive wear of the much more expensive rotors or drums. For that reason, consumers should ensure that the new brake pads installed are those specified or supplied by the vehicle's manufacturer.
Brake pads should always be replaced in pairs on both sides of a vehicle, as the different lining thicknesses (and possibly material types) will cause uneven braking, making the vehicle pull in the direction of the more effective brake. For most vehicles, replacing pads (and therefore linings) is easy for a mechanic, requiring a minimum of tools and time — the linings are designed to be consumable and should therefore be easy to service.
Brake linings can also be found just about everywhere there are braking systems and clutches, from
Cataloguing
There are different systems for the cataloguing of brake linings. The most frequently used system in Europe is the WVA numbering system.[5]
See also
References
- ^ T.P. Newcomb and R.T. Spurr, A Technical History of the Motor Car (Bristol/New York: Adam Hilger, 1989)
- PMID 2920147.
- ^ http://egilman.com/Documents/Asbestos/Experts/Paustenbach/Exponent[permanent dead link] Production/teta062006asbex5.pdf
- ^ "Ban on chrysotile asbestos - WorkSafe - Department of Commerce". Archived from the original on 2011-10-06. Retrieved 2011-08-11.
- ^ "WVA numbering system". Archived from the original on 2014-07-13. Retrieved 2009-10-05.