CPC Vehicle Safety Checks 2

Question 1

What is the minimum brake efficiency required for HGV service brakes at annual test?

Accepted Answer

50%

Answer

UK annual test standards require service brakes on HGVs to achieve a minimum efficiency of 50%, ensuring adequate stopping power for the vehicle type and weight.

Question 2

Under-inflated tyres on an HGV are dangerous because they:

Accepted Answer

Overheat, leading to structural failure and potential blowout, and increase fuel consumption and tyre wear

Answer

Under-inflation causes the tyre sidewall to flex excessively, generating dangerous heat that can cause structural failure and blowout, increases fuel consumption and accelerates irregular tyre wear.

Question 3

What type of fire extinguisher should be carried in the cab of an HGV, and what class of fire is it for?

Accepted Answer

Dry powder or CO₂ suitable for Class A (solids), B (liquids) and electrical fires

Answer

HGV cabs should carry a powder or CO₂ extinguisher suitable for the types of fire likely in a cab (fuel, electrical and general materials), covering multiple fire classes.

Question 4

Air brake systems must have sufficient pressure before moving the vehicle. What happens if air pressure is too low?

Accepted Answer

A warning alarm sounds and the spring brakes automatically apply preventing movement

Answer

Air brake systems are fail-safe: low air pressure triggers a warning and the spring (park) brakes apply automatically, immobilising the vehicle until sufficient pressure is built up.

Question 5

What is the purpose of checking the coupling mechanism of a semi-trailer before driving a combination?

Accepted Answer

To ensure the fifth wheel coupling is fully engaged and locked, preventing separation of the tractor and trailer unit during movement

Answer

An insecure fifth wheel coupling can result in trailer separation at speed — a catastrophic and potentially fatal event; visual and physical coupling checks are essential before every departure.

Driver CPC Practice Test

Driver CPC Practice Test

CPC Vehicle Safety Checks 2