All questions in this Heavy vehicle section ( Braking Systems ) are listed below. If you click on a question it will show you the possible answers that you might be asked in a theory test.

• When is trailer swing most likely to occur on a lorry and drawbar combination?
• Your vehicle is fitted with a 'diff-lock'. When would you normally use it?
• What colour is the auxiliary line on a three-line braking system?
• The emergency line is common to both two-line and three-line brake systems. What colour is it?
• Air-brake systems usually have two lines. Which additional line is fitted on a three-line system?
• In frosty weather, what precaution could a lorry driver take to prevent moisture from freezing in the air-brake system?
• How can a lorry driver avoid brake fade?
• When are exhaust brakes most efficient?
• What's the principal braking system on a lorry called?
• You're driving an articulated lorry. What could happen if you change to a lower gear while you're going too fast?
• When is an articulated vehicle most at risk of jack-knifing?
• Your lorry is stuck in snow. You use the diff-lock to move off. When should you switch the diff-lock off?
• Your tractor unit has three air lines. You're connecting to a trailer that has two air-line couplings. What colour is the line you shouldn't connect to the trailer?
• You're driving an articulated lorry that has three air lines connected to the trailer. What's the purpose of the red line?
• You're driving a tractor unit fitted with two air lines. You want to couple to a trailer that has three air-line couplings. How should the air lines be connected?
• Your lorry is equipped with anti-lock brakes. What's the correct procedure for stopping in an emergency?
• What does changing to a lower gear on a long downhill gradient help to avoid?
• You have to drive onto a muddy building site. Why should you switch on your diff-lock?
• How will anti-lock brakes improve your vehicle's safety?
• What could prevent air pressure from building up in an air-brake system in frosty weather?
• What should you do if the brake air-pressure warning light comes on while you're driving?
• You've just started the engine. What must you do if the brake air-pressure warning light is showing?
• Your vehicle is fitted with an anti-lock braking system. What's it designed to allow you to do?
• Your vehicle is fitted with an anti-lock braking system. When should you check that it's working properly?
• What will 'pumping' the brake pedal in a vehicle fitted with anti-lock brakes cause?
• You're driving a vehicle fitted with anti-lock brakes. What should you do when braking in an emergency?
• What's 'brake fade'?
• 'Brake fade' is a loss of effectiveness of the brakes when they overheat. When would 'brake fade' be most likely to happen?
• What should you do when driving a large vehicle down a steep hill?
• What should anti-lock brakes let you do when you have to stop in an emergency?
• Your vehicle has anti-lock brakes. How does this affect you when you're braking normally?
• When can an endurance brake (retarder) be especially useful?
• You're driving down a long hill. What should you use to prevent the brakes from overheating?
• What system is used to control a vehicle's speed without using the footbrake?
• When should an endurance brake (retarder) be used?
• Your vehicle is fully loaded. Where should you be braking when dealing with bends?
• A lorry is overtaking you on a two-lane motorway. What should you do if it doesn't have the speed to get past?
• What should you do after driving through a flood?
• What can coasting downhill seriously affect?
• When does 'brake fade' occur?
• How can you help to prevent 'brake fade'?
• What causes 'brake fade'?
• Where must extra care be taken when using an endurance brake (retarder)?
• You're stationary. The brake air-pressure warning light comes on. Why should you keep the parking brake on?
• You're about to drive a vehicle fitted with air-assisted hydraulic brakes. Why might the brake pedal feel hard when you press it?
• Your vehicle is fitted with an air-assisted hydraulic braking system. What would warn you that the air compressor is not working?
• Your vehicle is fitted with hydraulic brakes. Why might the brake pedal go down too far when it's pressed?
• You're about to drive a vehicle fitted with hydraulic brakes. What should you check before driving the vehicle?
• Your vehicle is fitted with air-assisted hydraulic brakes. What would warn you that there isn't enough air in the system?
• Which coloured band on the rev counter makes the best use of engine braking?
• Your vehicle is fitted with air brakes. What does it mean if a brake warning light shows when you've just started the engine?
• Your vehicle is fitted with air-assisted hydraulic brakes. What fault would you suspect if the brake pedal becomes hard to press?
• Which component will last longer when you use a retarder?
• What should you do when an air-pressure warning device activates?
• You're driving down a snow-covered hill. Why should you take care when using an independent endurance brake (retarder)?
• What should you avoid when using an independent endurance brake (retarder) on slippery roads?
• You're about to drive an unfamiliar vehicle. What should you do if you think there may be moisture in the air-brake reservoir?