There are a lot of oils in cars that need to be replaced regularly, but people tend to ignore very important brake fluids. Because many people think that brake fluid is only used to transmit braking force, as long as it is a lot, there is no need to change it. In fact, this is not entirely true.
What is the brake fluid
Almost all family cars have an oil brake system, which means that brake fluid is used to transmit braking force.
Below the brake pedal is the brake master cylinder, which can be simply understood as something like a syringe filled with brake fluid. When the brake is stepped on, the pedal drives the piston of the brake master cylinder to apply pressure to the brake fluid. The pressure passes through the brake fluid in the brake hose. It is transmitted to the brake cylinder of each wheel and pushes the cylinder piston to generate braking force.
Therefore, in principle, even if the brake oil is replaced with ordinary engine oil or even with water, the thrust of the brake master cylinder can be transmitted to the brake cylinder. But why have to use brake fluid instead of other fluids? There are mainly several reasons.
1. Thermal stability
When the brake is stepped on, the brake pads rub against the brake disc violently, and a lot of heat will be generated on the brake disc and the brake pad. If we rub our hands hard, it can be very hot, let alone a car. The weight of more than a ton depends on the friction between the small brake pads and the brake disc to stop it.
The brake discs are relatively large, and most of them have vents. The air flowing through during rotation can help dissipate heat.
The temperature of the brake pads is transmitted to the brake calipers. There are pistons on the brake calipers. When the brakes are stepped on, the power of the brake master cylinder is transmitted by the brake fluid and pushes the pistons to compress the brake pads to generate braking force. Therefore, there is a part of brake fluid in the brake caliper, and this part of the oil will heat up as the brake caliper heats up. If the brakes are frequently used and the brake caliper temperature is too high, the brake fluid will easily boil. When the brake fluid boils, gas will be generated, and the gas can be compressed, so the braking force of the master cylinder cannot be transmitted, and the brake will fail at this time.
Therefore, the brake fluid must have a sufficiently high boiling point and thermal stability to ensure that the brake fluid does not boil or deteriorate when the brake is overheated.
2. Lubricity
When the brake is stepped on, the pistons of the brake master cylinder and the sub-cylinder must reciprocate. In order to reduce wear, the brake oil must have a certain degree of lubricity.
3. Do not corrode the brake system
Brake fluid must exist in the brake system for a long time. The brake system has various metal pipes, rubber tubes, and rubber pads, so the brake fluid cannot corrode the brake system. As mentioned above, engine oil will corrode rubber, so it cannot be used as brake fluid.
Therefore, the brake fluid must have a relatively high boiling point, must have a lubricating effect, and cannot corrode the brake system. Therefore, the brake system can only be replaced with special brake fluid, and cannot be replaced by other fluids.
Failure to change the brake fluid may have the following negative effects:
1. The boiling point of brake fluid decreases
Brake fluid contains a certain amount of ethylene glycol, which easily absorbs water. When the water content of the brake fluid increases, the boiling point will decrease. There is not much brake fluid in the brake caliper. When the brake is overheated, the entire caliper is boiling the middle of the brake fluid like a pot, and the brake fluid may boil ahead of time. At this time, it may cause brake failure.
2. Increase the corrosion and wear of the brake system
The brake fluid will become dirty and deteriorated after a long time, which will increase the wear of the brake master cylinder and the sub-cylinder. After the wear is serious, the oil will start to leak. Once the oil leaks to the brake pads or brake discs, the brakes will fail. Even if it does not leak to the brakes, the brake fluid will leak out over a long period of time, and the brakes will not work.
Especially now that cars have ABS systems, ESP is also very popular, and the key component of these systems is the ABS pump, which is very precise inside. If the brake fluid is too dirty, it will increase the wear of the ABS pump. It is not cheap to replace it. .
Therefore, the brake fluid needs to be replaced regularly to keep its performance in good condition.