What can coasting downhill seriously affect?
- A The air brakes
- B The cooling system
- C The tachograph
- D The electrical systems
Why this is the answer
Air-brake systems rely on an engine-driven compressor to keep the reservoir tanks at their operating pressure. Coasting downhill and relying on the brakes to control your speed could result in the loss of sufficient air pressure to operate the brakes effectively.
Why the other answers don't fit
- B
- The cooling system — The cooling system is driven by the engine, which is still turning while you coast.
- C
- The tachograph — The tachograph records what the vehicle does; coasting does not harm it.
- D
- The electrical systems — Electrical systems run from the alternator and are unaffected.
Where this comes from
- Driving Buses and Coaches — section 7
- Driving Goods Vehicles — section 3, section 7
Rule numbers link to The Highway Code on gov.uk.
Where this question comes from
The question, its options and the explanation are reproduced word for word from the DVSA revision question bank under licence. The licence requires them to appear unaltered, so we cannot reword them and neither can anyone else — that is why you will meet the same wording on other sites. Everything else on this page is written by Theory Hub: the explanation of why each wrong answer is wrong, the topic guide and the revision notes.
Asked in: Lorry & Bus (LGV/PCV)
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