Revision question · Braking systems

You're driving an articulated lorry. What could happen if you change to a lower gear while you're going too fast?

Revision material from the imported DVSA bank includes source-checked Lanekind learning corrections. These corrections are not newly issued official examination questions, and practice does not reproduce a live test paper.

Answer options

The vehicle could jack-knife

The engine could stall

The brakes could fail

The trailer could uncouple

Show the answer

The vehicle could jack-knifeThis was the right answer

Severe braking or selecting a gear too low for your road speed can cause the tractor unit to slow more quickly than the trailer. The trailer can then pivot around the coupling (fifth wheel), causing the vehicle to jack-knife. Jack-knifing is more likely to occur with an unladen vehicle, particularly on a bend or curve.

Reviewed reading for this question

Brake before turning, not sharply in the bendReviewed guidance summary · These ask about drawbar trailer swing, an abrupt low-gear change, heavy braking and braking before a bend; all involve combining forces that destabilise the combination.

Loading the questions