In which of the following situations should you use the speed retarder when driving a bus in a mountainous terrain?
Show the correct answer
Correct answer
A. Always while braking.
Explanation
The question is about using the speed retarder, also simply called the retarder, when driving a bus in mountainous terrain. You should use it every time you brake - answer A.
The Road Traffic Act requires you to drive at a speed that ensures control of the vehicle, taking into account the shape of the terrain. In the mountains, descents are long, and frequent use of the service brake quickly overheats the linings and discs, which then lose their effectiveness. The retarder slows the bus down without using the service brakes, so you use it every time you slow down, and you keep the service brake cool for a sudden situation. Using it only on bends (answer B) or only when driving up to the top of a hill (answer C) would mean that on a descent all the work is done by the wheel brakes. On a slippery surface you use the retarder gently, so as not to lock the driving wheels and go into a skid.
Legal basis: Art. 19 para. 1 and para. 2 point 2 of the Road Traffic Act (Prawo o ruchu drogowym)