Brake fluid
1338292
226187037
2008-07-17T06:17:39Z
142.165.218.254
Added info on brake bleeding
{{Unreferenced|date=June 2008}}
{{cleanup|date=June 2008}}
'''Brake fluid''' is a type of [[hydraulic fluid]] used in [[hydraulic brake]] applications in [[motorcycle]]s, [[automobile]]s, [[light truck]]s, and some advanced [[bicycle]]s. It is used to transfer force under pressure from where it is created through [[hydraulic]] lines to the braking mechanism near the [[wheel]]s. It works because [[liquid]]s are not appreciably [[Physical compression|compressible]]. Braking applications produce a lot of [[heat]], so brake fluid must have a high [[boiling point]] to remain effective, and must also not [[freeze]] under normal temperatures. These requirements eliminate most [[water]]-based solutions.
Compatibility issues may exist between DOT3/4 brake systems and DOT 5 fluid. Specifically, silicon fluid may attack and harden some silicon based rubber seals such as caliper piston boots, which will cause the system to leak. Various grades of both DOT3 and DOT 4 fluid exist with different temperature ratings for different applications and manufacturer requirements for fluid types should be followed. <ref>http://www.xs11.com/tips/maintenance/maint1.shtml</ref>
Brake fluid comes in a number of forms, and is standardized worldwide by the [[United States Department of Transportation]] (DOT). [[DOT 2]] is essentially [[castor oil]]; [[DOT 3]], [[DOT 4]], and [[DOT 5.1]] are composed of various [[mineral oil]]s, [[glycol]] [[ester]]s, and [[ether]]s; some are [[synthetic oil]] based, and [[DOT 5]] is [[silicone]]-based. [[As of 2006]], most cars produced in the U.S. use DOT3{{Fact|date=April 2008}}.
Some very old British cars use [[Girling]] brakes, which are incompatible with DOT3 brake fluid. British-car dealers are careful in observing this precaution; but UK law does not require such observations be taken by commercial garages.
[[Glycol]] based fluids are half as compressible as silicone type fluids, even when heated{{Fact|date=April 2008}}. Less compressibility of brake fluid will increase pedal feel (firmness), but in either case this effect is minimal. The U.S. Army has used silicone brake fluid exclusively since 1982 successfully. [[Glycols]] are [[hygroscopic]] and will absorb water from the atmosphere, reducing the boiling point of the fluid and degrading hydraulic efficiency. Changing fluid on a regular basis will greatly increase the performance of the brake system, but this is often not a concern in passenger cars. On the other hand, changing fluid at least every several years will preserve the life of brake system components (by removing accumulated water and other contaminants, thereby reducing rust on internal components), and increase the overall reliability of the brake system.
[[Polyethylene glycol]], and other brake fluid ingredients may be [[corrosive]] to paint and finished surfaces such as [[Chrome plating|chrome]], and thus care should be taken when working with the fluid. Additionally, polyethylene glycol, in the concentrations found in DOT brake fluids, reacts violently, producing a large fireball, with some household chemicals, notably pool care products.{{Fact|date=September 2007}}
[http://forums.hotwheelscollectors.com/groupee/forums/a/tpc/f/58110277/m/83810577 Hotwheelscollectors.com] cites that hobby modellers use brake fluid as a safe (if somewhat slow) paint stripper. It is less likely to harm skin and will not harm plastics. Brake fluid can also be used as a releasing fluid for screw threads, provided no painted parts are involved.
==Components==
===Mineral-based===
*[[Alkyl ester]]
*[[Aliphatic]] [[amine]]
*[[Diethylene glycol]]
*[[Diethylene glycol monoethyl ether]]
*[[Diethylene glycol monomethyl ether]]
*[[Dimethyl dipropylene glycol]]
*[[Polyethylene glycol monobutyl ether]]
*[[Polyethylene glycol monomethyl ether]]
*[[Polyethylene oxide]]
*[[Triethylene glycol monobutyl ether]]
*[[Triethylene glycol monoethyl ether]]
*[[Triethylene glycol monomethyl ether]]
===Silicone-based===
*[[Di-2-ethylhexyl sebacate]]
*[[Dimethyl polysiloxane]]
*[[Tributyl phosphate]]
==References==
{{Reflist}}
==See also==
*[[Disc brake]]
*[[Drum brake]]
*[[Brake bleeding]]
*[[Hydraulic brake]]
*[[Hydropneumatic]]
==External links==
*[http://www.carcare.org/Brakes/brake_fluid.shtml Car care council]
*[http://auto.howstuffworks.com/question451.htm ''How Stuff Works: What are the different types of brake fluid?'']
*[http://www.stoptech.com/tech_info/wp_brakefluid_1a.shtml StopTech: Brake Fluid 1A]
*[http://www.fordf150.net/howto/bleedbrakes.php Brake Bleeding]
[[Category:Vehicle braking technologies]]
[[Category:Automotive chemicals]]
[[de:Bremsflüssigkeit]]
[[et:Pidurivedelik]]
[[es:Líquido de frenos]]
[[ja:ブレーキフルード]]
[[pl:Płyn hamulcowy]]
[[pt:Fluido de freio]]