Vehicle Knowledge, Load and Driving Technique for Heavy Vehicles
What this domain tests
The exam checks daily vehicle checks, braking systems, coupling, tyre rules and how load affects handling. You must know what a warning lamp means and how to drive a laden lorry safely.
Core rules
- Do a walk-around check before driving: tyres, lights, mirrors, air leaks, coupling, load securing and warning lamps.
- Air-brake systems need pressure. If the pressure warning sounds or pressure falls, stop safely and find the fault; do not continue.
- Check tyre tread and pressure. Heavy vehicles need adequate tread for the season; winter tyres are required in winter conditions, and studded tyres have date restrictions.
- Know the difference between service brake, parking brake, retarder and engine brake. On long descents, select a low gear and use the retarder rather than riding the brakes.
- Load position changes axle loads and stability. Keep the centre of gravity low and within the permitted axle loads shown on the vehicle documents.
Worked example
You drive a loaded tipper down a long mountain descent. The service brakes begin to fade after repeated use. Correct action: select a lower gear, use the engine brake or retarder, and stop at a safe place to let the brakes cool. Do not continue relying on the footbrake, and never use the parking brake as a running brake.
Traps that cost marks
Believing ABS shortens every stopping distance - on gravel or ice it may not. Checking coolant by opening a hot radiator cap. Forgetting that a fully laden lorry needs a longer braking distance and wider turns. Ignoring an air-pressure warning because the brakes still feel normal.
Key points
- Stop for low air-pressure warnings; brakes may fail without warning.
- Use a low gear and retarder on long descents to avoid brake fade.
- Load position affects axle loads, steering and stability.
- ABS does not guarantee a shorter stop on low-friction surfaces.