What causes ignition in a diesel oil?
Show the correct answer
Correct answer
C. High temperature of the air.
Explanation
In the photo, you can see the open compartment of a diesel engine at the rear of a bus. Ignition in a diesel engine is caused by the high temperature of the air, which heats up during compression - answer C.
The Road Traffic Act requires a vehicle to be maintained so that using it does not endanger safety - and to take care of this, a bus driver must understand how the engine works. A diesel engine has no spark plugs: the piston compresses the air very strongly, and the air heats up to a temperature of several hundred degrees. Diesel oil injected at that moment ignites by itself. Low compression pressure (answer A) and low temperature of the compressed air (answer B) are causes of starting problems, not of ignition. That is why a diesel engine is harder to start in winter, and glow plugs or an intake air heater make starting easier.
Legal basis: Art. 66 para. 1 point 1 of the Road Traffic Act (Prawo o ruchu drogowym)