In which of the following cases can you use an emergency switch-off of the engine?
Show the correct answer
Correct answer
C. While stopping the vehicle.
Explanation
In the photo you can see the dashboard of a bus, and an arrow points to a "STOP" switch - the emergency engine stop switch. You may use it when the vehicle is stopped - answer C.
The emergency engine stop switch is used to turn off the engine immediately, for example when smoke is coming out of the engine compartment or something is endangering people near the vehicle. Using it while driving is dangerous: when the engine is turned off, the power steering stops working and the compressor no longer refills the air in the braking system, so steering and braking a heavy bus becomes very difficult. That is why on a sharp mountain bend (answer A) switching off the engine could mean that you do not make it round the bend. With damaged brakes on a downhill slope (answer B) it is even worse - you may lose engine braking and the retarder, especially with an automatic gearbox, and the air supply in the brakes will quickly run out. The Road Traffic Act requires a vehicle to allow reliable use of the steering and braking controls - switching off the engine while driving takes away part of this reliability. First you stop the bus, and only then do you use the switch.
Legal basis: Art. 66 para. 1 point 1 and 5 of the Road Traffic Act (Prawo o ruchu drogowym)