UK PCV Theory Braking Systems and Technique Questions and Answers

Question 1

You are driving a coach down a long, steep hill. To control your speed and prevent the service brakes from overheating, what is the most effective technique?

Accepted Answer

Select a low gear and make use of the engine brake or retarder.

Answer

Using a low gear allows the engine's natural resistance (engine braking) to help control the vehicle's speed. This effect is enhanced by an auxiliary braking system like an engine brake or retarder. This technique prevents the service brakes (footbrake) from overheating and losing effectiveness, a dangerous condition known as 'brake fade'.

Question 2

What is the primary purpose of an Anti-Lock Braking System (ABS) on a PCV?

Accepted Answer

To allow the driver to maintain steering control during emergency braking.

Answer

The main function of ABS is to prevent the wheels from locking up during heavy braking. By preventing the wheels from skidding, it allows the driver to maintain steering control, which is crucial for avoiding a hazard. While ABS can sometimes reduce stopping distances on good surfaces, its primary safety benefit is the retention of steering control.

Question 3

Which of the following describes how an exhaust brake works to slow a vehicle?

Accepted Answer

It restricts the flow of gases leaving the engine's cylinders.

Answer

An exhaust brake is a valve that closes the exhaust path, creating back-pressure in the exhaust manifold and cylinders. This increased pressure makes it harder for the pistons to push exhaust gases out, which slows the engine's rotation and, in turn, slows the vehicle.

Question 4

A warning light on your dashboard indicates low air pressure in the braking system. You have stopped the vehicle safely. What is the most appropriate action to take?

Accepted Answer

Secure the vehicle with the parking brake and investigate the cause, seeking assistance if necessary.

Answer

Low air pressure is a critical safety defect in an air brake system, as it can lead to total brake failure. The driver must not continue the journey. The correct procedure is to ensure the vehicle is safely parked (using the parking brake), investigate the cause (such as a leak), and call for technical assistance. Driving a vehicle with known critical brake defects is illegal and dangerous.

Question 5

The term 'brake fade' refers to a reduction in braking efficiency. What is the most common cause of this phenomenon?

Accepted Answer

Excessive heat build-up in the braking components from prolonged use.

Answer

Brake fade is the loss of braking power that occurs when the braking system overheats. This typically happens during long descents or repeated heavy braking. The high temperatures can cause the brake pads to lose their frictional properties and can even boil the brake fluid, making the brakes feel spongy and ineffective.

DVSA UK Driving Theory Practice Test

DVSA UK Driving Theory Practice Test

UK PCV Theory Braking Systems and Technique Questions and Answers