The booster is a part of the assembly kit of the main tandem brake cylinder. It is not disassembled and can only be repaired by the manufacturer.
The amplifier operates on the basis of vacuum, taken in cars with a gasoline engine from the suction pipeline, and in cars with a diesel engine from a separate vacuum pump. The pressure during testing is 0.08 MPa.
The brake booster only works when the engine is running. When driving with the engine stopped, the brakes work, but to achieve the desired braking effect, you need to press the pedal harder.
The booster consists of a chamber made up of two tightly connected steel stampings - a cover and a bottom. The piston assembly is inserted inside. It consists of a plastic piston, there is also a control valve with steel segments, a support and a lining, ensuring the progressiveness of the booster. The next parts of the piston assembly are: a button acting on the THV piston, and a piston with a membrane. Inside the booster chamber there is a spring that returns the piston assembly to its original position after braking. The chamber is sealed. The booster is controlled by a rod from the brake pedal.
The operation of the booster is as follows: when you press the brake pedal with your foot, the control valve is pressed into the plastic piston and through the steel segments and the lining, the button is set in motion, acting on the THV piston.
When the resistance on this piston increases, the rubber part of the control valve sits on the seat of the plastic piston.
As a result, the connection between both volumes of the booster chamber is broken. With further movement of the control piston, the booster volumes on the cover side are connected to the atmosphere. The difference in pressure on both sides of the piston assembly causes it to move further, the movement is transmitted by the button on the THV and increases the pressure in the liquid brake system. Therefore, the degree of amplification depends on the force developed by the pedal and on the vacuum created in the booster.
The required braking performance is achieved by the magnitude of the mechanical transmission of the steel segments through which this force is transmitted.
When the brake pedal is released, the spring returns the piston assembly to its original position and the vacuum in both volumes of the booster chamber is immediately equalized.
If the booster is not sealed properly or if the engine is not running, it is still possible to mechanically control the brakes, naturally without booster.
Material is available on the website SkodaBook.ru
Examination
1. With the engine not running, press the brake pedal several times with your foot to relieve any remaining vacuum in the system.
2. Then press the pedal again and hold it in this position.
3. Then start the engine.
4. If the amplifier is working, the pressed pedal should still settle by about 10 mm.
5. If the pedal does not fall through, you need to visit a service center to determine the cause of the malfunction.