What is Brake Fluid?
2 Answers
Brake fluid is a liquid medium used in hydraulic brake systems to transmit braking pressure, employed in vehicles equipped with hydraulic braking systems. It is an indispensable component of the braking system, serving as a force-transmitting medium. Since liquids cannot be compressed, the pressure output from the master cylinder is directly transmitted to the wheel cylinders through the brake fluid. There are three main types of brake fluid: 1. Castor oil-alcohol type: Composed of refined castor oil (45%-55%) and low-carbon alcohols (ethanol or butanol) (55%-45%), it forms a colorless or light yellow clear transparent liquid after precipitation, known as alcohol-based automotive brake fluid. Castor oil plus ethanol is referred to as Alcohol Type 1, while castor oil plus butanol is Alcohol Type 3. Alcohol-based brake fluids are easy to produce with readily available raw materials and simple synthesis processes, offering good lubrication properties. However, they have low boiling points and unstable properties at low temperatures. Alcohol Type 1 produces ethanol vapor above 45°C, leading to vapor lock. At -25°C, castor oil precipitates as a milky white colloidal substance, increasing with decreasing temperature and potentially clogging the brake system, causing it to malfunction. Tests on Alcohol Type 3 rubber cups showed slight discoloration of the brake fluid, with butanol causing minor dissolution and corrosion of rubber, and white precipitates appearing at -28°C. 2. Synthetic type: Made by blending ethers, alcohols, esters, etc., with additives for lubrication, oxidation resistance, rust prevention, and anti-rubber swelling. 3. Mineral oil type: Produced by adding thickeners and other additives to refined light diesel fractions.
Brake fluid is the stuff used in our car's braking system. Simply put, it's a special liquid stored in the brake lines that helps transfer the force from your foot to the wheels when you press the brake pedal. I once experienced soft brakes while driving, and when I took it to the repair shop, they found the brake fluid had absorbed too much moisture, lowering its boiling point and making it prone to bubbling under high temperatures, which affected braking performance. It must be heat-resistant and corrosion-resistant, with common types like DOT3 or DOT4. During maintenance, it should be replaced every two years or every 20,000 kilometers—otherwise, degraded fluid can make the car unstable when stopping. This is crucial for driving safety; brake failure on the highway would be disastrous. So, drivers should stay vigilant and schedule regular checks without cutting corners. Remember, brake fluid isn't something you can replace with just any liquid—it must prevent rust and keep the hydraulic system running smoothly.
