What may be the cause of lack of tightness in the pneumatic braking system applied in buses?
Show the correct answer
Correct answer
A. A damage to air valves.
Explanation
The question is about the cause of a leak in the air brake system of a bus. It can be damage to the air valves - answer A.
The Road Traffic Act requires a vehicle to be maintained so that using it does not endanger safety and so that the driver can use the brakes reliably. The air brake system consists of a compressor, air tanks, pipes and many valves - a damaged diaphragm or seal in a valve lets air escape, which you can hear as a hiss and see as a pressure drop on the pressure gauge. Excessive play in the brake shoe expanders (answer B) lengthens the brake stroke, but does not make air escape. Worn brake discs (answer C) make braking worse, but do not affect whether the system is airtight. With a leak, the system may not build up the required pressure, and with a large loss of air the spring brakes will be applied.
Legal basis: Art. 66 para. 1 point 1 and 5 of the Road Traffic Act (Prawo o ruchu drogowym)