How do speed limiters normally work?
- A By applying the service brake
- B By applying the secondary brake
- C By reducing the fuel supplied to the engine
- D By changing to a lower or higher gear
Why this is the answer
Most speed limiters work by taking a speed signal from the tachograph and transmitting it to the engine management system. This reduces the fuel supply to the engine, and allows the speed of the vehicle to be controlled to specific limits. The speed at which a limiter is set must be shown on a plate clearly displayed in the cab. You should be aware of the effect a speed limiter will have on your vehicle, especially when overtaking.
Why the other answers don't fit
- A
- By applying the service brake — A limiter does not brake; it stops the engine delivering more.
- B
- By applying the secondary brake — The secondary brake is a back-up for a failure.
- D
- By changing to a lower or higher gear — Gear selection stays with the driver or the automatic box.
Where this comes from
- Driving Buses and Coaches — section 1
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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