TheoryHGV Theory UK Practice Questions
Free HGV Theory UK practice questions with answers and plain-English explanations. Browse the PDF, video and online mock test.
HGV Theory UK Questions
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Q1You are driving a fully laden articulated lorry down a long, steep gradient. The retarder has been active for several minutes and you notice it is becoming less effective. What is the most likely cause?
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✓ Correct answer: The retarder oil has become overheated and lost viscosity
Retarders (hydraulic or electromagnetic) generate heat when absorbing kinetic energy; prolonged use causes the fluid or components to overheat, reducing braking effectiveness — the driver should use lower gears and allow cooling rather than relying solely on the retarder.
Q2An articulated vehicle with a 13.6 m semi-trailer is negotiating a tight left-hand roundabout. The driver positions the cab close to the right-hand kerb before turning. Why?
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✓ Correct answer: To allow the trailer's rear overhang to clear the left-hand kerb during the turn
The swept path of a long semi-trailer means the rear wheels cut significantly inward on a left turn; by swinging the cab rightward first, the driver increases the radius the trailer tyres follow, preventing the rear corner from mounting or striking the left-hand kerb.
Q3You are about to drive under a railway bridge. Your loaded vehicle is 4.1 metres high and the posted clearance is 4.2 metres. What should you do?
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✓ Correct answer: Find an alternative route, because posted clearances include no tolerance and your load measurement may not be exact
DVSA guidance warns that posted bridge heights are nominal minimums and load heights measured at rest can increase due to road camber, suspension sag changes, or measurement error — a margin of only 100 mm is unsafe and an alternative route should be used.
Q4You are descending a steep hill in a 44-tonne vehicle. You selected the correct gear at the top, but your speed is now creeping above the safe limit. What is the FIRST corrective action you should take?
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✓ Correct answer: Apply steady progressive pressure to the service brake and, once speed is controlled, change to a lower gear if necessary
The DVSA advises using progressive service braking to control speed on descents and only changing to a lower gear once speed is already controlled — attempting to downshift while accelerating risks transmission damage and loss of control.
Q5When driving a long vehicle, you notice that the nearside rear wheels are tracking over a raised kerb during a left turn at a junction. What does this indicate about your line choice?
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✓ Correct answer: You turned too early, causing the trailer to cut in
Turning the steering too early on a left bend reduces the arc available to the trailer wheels, causing the rear to cut inward and mount the kerb — the correct technique is to delay the turn and take a wider initial line.
Q6You are driving a PCV with a high centre of gravity on a cambered rural road. The nearside wheels begin to follow a dip in the road surface. What specific risk does this create for this vehicle type?
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✓ Correct answer: The camber reduces effective tyre contact area, increasing rollover risk
A high-sided PCV has a high centre of gravity; when nearside wheels drop into a road dip, the vehicle's effective lean angle increases and the stability margin against rollover is significantly reduced — drivers must maintain appropriate speed and smooth steering.
Q7What is the maximum overall length permitted for a standard articulated lorry (tractive unit plus semi-trailer) on UK roads without a special order?
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✓ Correct answer: 16.5 metres
UK road traffic regulations specify a maximum overall length of 16.5 metres for a standard articulated vehicle (tractive unit and semi-trailer combined) without requiring an abnormal load authorisation.
Q8You are driving a vehicle with an automatic gearbox down a long hill. To engage engine braking, you move the selector to position '3'. What should you be aware of?
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✓ Correct answer: The gearbox will hold third gear, but downshifting at excessive speed risks transmission overspeed damage
Selecting a lower range on an automatic gearbox locks out higher gears and enables engine braking, but the driver must ensure vehicle speed has been reduced to within the safe rev range for that gear before selecting it to avoid transmission damage.
Q9You are about to cross an old humpback bridge in a 32-tonne rigid vehicle. The bridge has no weight restriction sign. What should you do?
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✓ Correct answer: Check the OS map or bridge management authority data, as many historic bridges have structural limits not yet signed
Not all structurally limited bridges carry up-to-date signage; DVSA guidance and the Highway Code advise professional drivers to use appropriate route-planning resources and consult bridge owners when in doubt, especially for heavy vehicles.
Q10You are driving an unladen 44-tonne artic on a motorway in strong crosswinds. You notice the empty trailer is yawing slightly. Compared to a fully laden trailer, what makes the unladen trailer MORE susceptible to yaw instability?
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✓ Correct answer: Lower mass reduces tyre cornering stiffness relative to aerodynamic side forces, making yaw harder to resist
With low mass, the inertial resistance to lateral movement is reduced; aerodynamic side forces (which are mainly a function of body area, not mass) therefore represent a much higher proportion of the total restoring force, making yaw oscillation more likely in high winds.
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