Brake fluid is a type of hydraulic fluid used in the application of hydraulic brakes and hydraulic couplings on cars, motorcycles, light trucks, and some bicycles. This is used to transfer strength into pressure, and to strengthen the braking power. It works because the liquid can not be compressed.
Most of the brake fluids used today are glycol-based, but mineral oils (liquide liquids hydrolique minà © Å © ral (LHM)) and silicone-based liquids (DOT 5) also available.
Video Brake fluid
Standar
Brake fluids must meet certain requirements as defined by standards set by organizations such as the Society of Automotive Engineers (SAE), or local government equivalents.
SAE has published standards J1703, J1704, and J1705, which reflects the higher performance for brake fluid. The International Standards Organization has published ISO 4925 standards, defining equivalent classes 3, 4, and 5, as well as classes 5-1 and grade 6.
Most of the brake fluid sold in North America is classified by the US Department of Transport (DOT) under its own ranks such as "DOT 3" and "DOT 4" and is widely used in other countries. Their classification broadly reflects SAE specifications, but with local details - Alaska and Azores for example, have different normal temperature and humidity ranges to consider. DOT 3 is equivalent to SAE J1703 and ISO grade 3, DOT 4 to SAE J1704 and ISO grade 4, etc.
All approved fluids must be colorless or yellow to be acceptable for US road use, except for DOT 5 silicon, which must be purple.
Maps Brake fluid
Characteristics
Brake fluid must have certain characteristics and meet certain quality standards in order for the braking system to function properly.
Viscosity
For reliable and consistent brake system operation, brake fluid must maintain a constant viscosity under various temperatures, including extreme cold temperatures. This is particularly important in systems with anti-lock (ABS) braking systems, traction control, and stability control (ESP), since these systems often use micro valves and require very fast activation. DOT fluid 5.1 is determined with low viscosity at various temperatures, although not all cars equipped with ABS or ESP specify DOT 5.1 brake fluid.
Boiling point
Brake fluids are subjected to very high temperatures, especially in drum brake wheel cylinders and disc brake calipers. Must have a high boiling point to avoid evaporation on the line. This evaporation creates a problem because the steam is very compressible relative to the liquid, and therefore negates the hydraulic braking transfers - so the brakes will fail to stop the vehicle.
Quality standards refer to "dry" and "wet" boiling points of brake fluid. The wet boiling point, which is usually much lower (although above the most normal servicing temperature), refers to the boiling point of the liquid after absorbing a certain amount of moisture. These are several (one digit) percent, varying from formulation to formulation. Glycol-ether brake fluids (DOT 3, 4, and 5.1) are hygroscopic (absorbing water), which means they absorb moisture from the atmosphere below normal moisture levels. Non-hygroscopic fluids (eg silicon/DOT 5 and mineral-based formulations) are hydrophobic, and can maintain an acceptable boiling point during the service life of the liquid.
Silicone based fluids are more compressible than glycol based fluids, which cause brakes with spongy feelings. This has the potential to experience phase/pool puddles and freezing/boiling in the system over time - the primary reason for single-phase hygroscopic fluids is used.
The wet boiling point is defined as 3.7% water by volume.
Corrosion
Brake fluid should not corrode metal used in components such as calipers, wheel cylinders, master cylinders and ABS control valves. They should also protect against corrosion when moisture enters the system. Additives (corrosion inhibitors) are added to the bottom liquid to achieve this. Silicon is less corrosive for painting unlike DOT-based fluid glycol ether.
The advantage of brake oil based on CitroÃÆ''N LHM mineral oil is the absence of corrosion. The seal can wear out at high mileage but on the contrary the system has a tremendous longevity. It can not be used as a substitute without replacing the seal due to incompatibility with the rubber.
Compressibility
Brake fluids should maintain a low level of compressibility, even with varying temperatures to accommodate different environmental conditions. This is important to ensure a consistent brake pedal. As compressibility increases, more traveling the brake pedal is required for the same amount of piston caliper brake force.
Service and maintenance
Most automotive professionals agree that glycol based brake fluids, (DOT 3, DOT 4, DOT 5.1) should be watered, or modified, every 1-2 years in non-racing conditions. Many manufacturers also require periodic fluid changes to ensure reliability and safety. Once installed, the moisture diffuses into the liquid through the brake hose and rubber seal and, finally, the fluid must be replaced when the water content becomes too high. Commercial testers and test strips are commercially available to measure moisture content, but moisture test strips are taken from the market because they absorb moisture in the air before they can be used. Corrosion inhibitors also decrease over time. The degraded inhibitor allows corrosion in the braking system. The first corrosive metal is copper. You can specify when to replace brake fluid when copper ions reach 200ppm. New liquids should always be stored in a sealed container to avoid moisture interference.
DOT 2 (mineral oil) DOT 5 (silicone) fluid is not hygroscopic and should not be replaced when moisture becomes too high. Ideally, silicone fluids should be used only to fill non-ABS systems that have not previously been filled with glycol based fluids. Any system that has used a glycol based liquid (DOT 3/4/5.1) will contain moisture; glycol fluid spreads moisture throughout the system and contains corrosion inhibitors. Silicone fluid does not allow moisture to enter the system, but does not dissolve all that is already there. A system filled from dry with a silicone fluid does not require fluids to be changed at intervals, only if the system has been disrupted for repair or renewal of the component. The US armed forces have been standardized in silicone brake fluids since the 1990s. Silicone fluids are widely used in cold climates, especially in Russia and Finland.
A small decrease in brake fluid levels in the cylinder master reservoir can be "terminated" but if the level continues to fall, the cause should be investigated and corrected. The level of brake fluid in the master cylinder will drop due to coating (pads or shoes) and the caliper or cylinder wheel extends even further to compensate. Overspill from pushing the piston back should be avoided, because the glycol based fluid will rapidly lift or disarm the paint and other coatings when in contact (can be removed quickly washed with water, not wiped). Brake fluid levels may also be low due to leakage, which can result in a loss of hydraulic pressure and consequently a significant loss of braking ability. Modern cars have an excess of hydraulic circuits (two separate circuits) to ensure against total hydraulic failure.
Brake fluid with different DOT ratings can not always be mixed. DOT 5 should not be mixed with others because mixing glycol with silicone fluid can cause corrosion due to trapped moisture. DOT 2 should not be mixed with others. DOT 3, DOT 4, and DOT 5.1 are all based on glycol esters and can be mixed, although it is better to completely replace the existing liquid fresh to obtain the specified performance.
Cairan rem beracun dan dapat merusak permukaan yang dicat.
Komponen
Castor oil-based (pra-DOT , DOT 2)
- Minyak jarak
- Alkohol, biasanya butanol (cairan merah/merah) atau etanol (cairan kuning) (metanol)
Glycol- berdasarkan (DOT 3, 4, 5.1)
- Alkyl ester
- Aliphatic amine
- Diethylene glycol
- Diethylene glycol monoethyl ether
- Diethylene glycol monomethyl ether
- Dimetil dipropilena glikol
- Polyethylene glycol monobutyl ether
- Polyethylene glycol monomethyl ether
- Polietilena oksida
- Trietilen glikol monobutil eter
- Triethylene glycol monoethyl ether
- Trietilen glikol monometil eter
Berbasis silikon (DOT 5)
- Di-2-ethylhexyl sebacate
- Dimethyl polysiloxane
- Tributyl fosfat
Lihat juga
- Hidropneumatik
- Hukum Pascal
Referensi
Tautan eksternal
- Dewan perawatan mobil
- Cara Kerja Stuff: Apa saja jenis cairan rem yang berbeda?
- StopTech: Brake Fluid 1A
Source of the article : Wikipedia
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