What may be the cause of an extended braking distance of a truck?
Show the correct answer
Correct answer
C. Contamination of the friction elements of the braking system with oil or lubricant.
Explanation
In the photo you can see the rear of a lorry with a coupling, and on the road surface tyre marks left by braking. A longer braking distance may be caused by oil or grease contaminating the friction elements of the braking system - answer C.
The Road Traffic Act requires a vehicle to be maintained so that using it does not endanger safety. A brake works through the friction of the lining against the drum or disc; oil or grease that gets onto these surfaces - for example from a leaking hub or from careless greasing - reduces the coefficient of friction and the braking force falls, even though you press the pedal just as hard. In a combination weighing several dozen tonnes, this results in a longer braking distance and the vehicle pulling to one side, because usually only one wheel is contaminated. Pressing the pedal harder (answer A) and the correct, high pressure in the air brake system (answer B) increase the braking force rather than reduce it - and they are not the vehicle faults that this question asks about.
Legal basis: Art. 66 para. 1 point 1 of the Road Traffic Act (Prawo o ruchu drogowym)