brake fluid

Hydraulic brake actuator transmits the brake pressure from the master cylinder to the caliper wheel brake.

Brake fluid is a mixture of glycol polygylcolethers and several other components. This yellowish liquid is very poisonous and aggressive to paintwork, but it does not destroy the metal and rubber parts and components. The operating range in which the liquid maintains its properties, is from -40 to 260 ?� C.

The disadvantages include the fact that the brake fluid is hygroscopic - it absorbs moisture from the air, so fluid, long stored in an open container, use is not recommended. Moisture can also enter the liquid poured into the braking system, for example, from the air tank through microscopic or leaking locations on the brake pipes and hoses. Such moisture absorption leads not only to the corrosion of metal parts of the braking system, but also significantly lowers its boiling point. Even at 2.5% water content in the brake fluid boiling point is about 150 ?� C. This is particularly dangerous when heavy braking, as in this case, the brake may be very hot, and near them in the brake fluid may form vapor bubbles. This increases the stroke of the brake pedal, and in some cases may even pedal to "fall". In this case, the pressure will quickly pumping the brake pedal.

This effect is especially dangerous after heavy braking when the vehicle is stopped, because due to lack of a counter-flow of the air flowing around the brakes heat up even more, and the highest temperature is maintained for another 15 minutes of parking. In this case, only after 30 minutes, the temperature of brake fluid becomes normal. To eliminate this effect regulation prescribes maintenance to replace the brake fluid every year. The brake fluid must comply with safety standards FMVSS ?�571.116 DOT 4 specifications and SAE J1703. All liquids such specifications can be mixed.

The brake fluid level is too low

When the brake linings in the operation of a vehicle wear out, the brake fluid level approaches the bottom mark. This is quite normal, since the worn brake linings projecting from the cylinder piston disc brakes reserve cylinders larger volume, which is filled with brake fluid. The critical moment is when the fluid level in one part of the tank has dropped below the mark ?�MIN?�. Since the brake fluid does not evaporate and is not consumed, it can emerge only at the site of injury. Therefore, as soon as possible it is necessary to determine the location and repair.

Replacing brake fluid

The need to replace the brake fluid is caused not only the risk of bubbles, but also the danger of corrosion in the brake cylinder and the pipe because of the brake fluid to soak into the water. When replacing brake fluid must act as well as in the air and removing. To replace the reserves of 2 liters of fresh brake fluid.

Removal of air from a hydraulic drive of brakes

The air in the brake hydraulic drive significantly reduces braking efficiency. The air can get into the hydraulic system as a result of depressurization at repair, replacement of separate knots or a brake liquid. The presence of air in the drive indicate an increased brake pedal travel and its "softness". Before air removal check up tightness of all knots of a drive of brakes and their connections.

1. Remove the lid from the tank and fill it with fresh brake fluid up to the upper mark. In the process of removing air, make sure that the brake fluid does not drop below the middle of the tank.

2. Connect one end of the vinyl tube to the screw to remove the air, and the other end lower in the capacity half filled with brake fluid (Fig. 6.1).

3. Slowly repeatedly press the brake pedal.

4. When the brake pedal depressed, unscrew the screw to remove the air so that the liquid began to flow. Without releasing the pedal, tighten the screw of removal of air.

5. Repeat steps. 3 and 4 as long as the brake fluid is not air bubbles.

6. Tighten the screw to remove the air torque 7-13 Nm.

7. Repeat this procedure for each wheel in the sequence shown in Fig. 6.2.