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Common theory questions

What is the "jackknife effect"?

When you drive with a trailer coupled to your car and apply the brakes there is a risk that the car will brake more effectively than the trailer. This risk increases if the road is slippery – especially on downhill slopes and in curves.

If this happens, the rear end of the trailer can, in a worst case scenario, slide to the right or the left – causing the car and trailer to fold up like a jackknife. This is called the jackknife effect and is a very dangerous situation as the vehicle combination becomes uncontrollable.

The best way to minimise the risk of jackknifing is to drive in a calm and careful manner that allows you to stop without having to brake hard.