You're about to start a journey in very frosty weather. What's the likely cause of low air-brake pressure?
- A Engine temperature too low
- B Weak engine anti-freeze mixture
- C Brake pedal needs adjustment
- D Frozen moisture in the storage tanks
Why this is the answer
Air-brake systems use air from the atmosphere, which contains moisture. The moisture condenses under pressure, resulting in water in the system. Make sure the air tanks are drained daily to remove any water and to help prevent the system from freezing in cold weather.
Why the other answers don't fit
- A
- Engine temperature too low — A cold engine affects starting and running, not the air in the brake reservoir.
- B
- Weak engine anti-freeze mixture — Anti-freeze protects the cooling system, which is a separate circuit entirely.
- C
- Brake pedal needs adjustment — Pedal adjustment changes travel, and it is not a cold-weather fault.
Where this comes from
- Driving Buses and Coaches — section 11
- Driving Goods Vehicles — section 11
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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