D licence questions
DMechanics and maintenance·126 questions
Mechanics and maintenance questions — D licence
126 exam-style Mechanics and maintenance questions for the D licence with correct answer and explanation. Practice free, no signup.
- When snow chains are the chosen anti-skid option for a bus, what minimum placement does the General Vehicle Regulations require, while also following fitting instructions?
- On a new tyre, the label in the image provides information on environmental and safety aspects. What information does this label include, among other things?
- In a lorry with a transmission-mounted hydraulic retarder, which wheels receive its retarding effect?
- In a vehicle whose cooling system has an expansion tank with level marks, where do you check the coolant level according to the manufacturer’s instructions?
- A 24 V starting system uses two identical compatible 12 V batteries. Which connection adds their nominal voltages?
- In a D1 or D bus, correct tire pressure:
- Two compatible, identical 12 V batteries form the manufacturer-specified supply for a 24 V starter motor. How must they be connected together to add their voltages?
- Outside a built-up area, a two-wheeled bicycle overtakes your bus. What minimum lateral separation must it leave between itself and the bus’s outermost parts?
- When parking a bus on a steep gradient and leaving the driving position, how must you secure it against rolling, in addition to the other precautions?
- For a flooded lead-acid battery whose manufacturer permits electrolyte inspection and topping up, what maintenance is correct?
- As a general rule, what is the first measure that should be taken to control a heavy bleed in a leg?
- In an air-brake system equipped with an air dryer, what function helps prevent ice forming in the lines?
- In a diesel engine with a conventional mechanical injection pump, which assembly includes the governor that limits maximum engine speed?
- If the carriageway you are driving on is wet, the braking distance will be:
- The gears of the gearbox and differential bevel gears are generally lubricated with:
- How often must a bus that is four years old undergo the periodic technical inspection?
- To check a bus engine’s oil level correctly, which procedure should you follow?
- A bus has hydraulic power steering with a reservoir and level marks. Should the driver check its fluid?
- On a bus with hydraulically operated clutch controls and a separate fluid reservoir, where is fluid added when the manufacturer’s manual indicates it is necessary?
- What is the function of the intercooler?
- In a combustion engine with a turbocharger and intercooler, where is the intake air filter located?
- If an exhaust silencer is broken and no longer properly attenuates engine noise, what effect does this have?
- Under normal conditions, how is the tyre prevented from coming off the rim?
- What does the word “TUBELESS” written on the side of a tyre indicate?
- Under the generic Annex IX limit, what is the maximum authorised mass of a two-axle Class II or III bus?
- In a diesel engine, black smoke from the exhaust can indicate...
- What function does the radiator perform?
- Proper engine maintenance can directly affect...
- When climbing a slope in a manual vehicle, engine revs fall because the selected gear is too high to maintain progress. What should you do?
- To compare tyre inflation pressure with the manufacturer’s recommended cold-pressure value, when should you check the tyres?
- To move off and accelerate a loaded bus forwards, how must the tractive force at the wheels compare with the forces opposing forward movement?
- After successfully passing your bus's periodic technical inspection, where will you place the sticker?
- In a conventional drivetrain with a propeller shaft and crown wheel and pinion final drive, which mechanism provides a fixed reduction before the wheels in addition to the gearbox?
- To keep the engine in good condition, it is better to…
- You witness a road accident with possible injuries and assistance has not yet been organised. If you can help without creating another danger, how should you act?
- In a vehicle with a conventional electric starter motor, which component supplies the electrical energy to turn it?
- Why is the oil filtered?
- What type of brake is shown in the photograph?
- Should you check the coolant level in your bus's engine cooling system?
- Which instrument indicates the oil-pressure value in the lubrication circuit?
- You drive a bus and intend to overtake a motorcycle outside a built-up area. Under the current general rule, what lateral clearance must you leave?
- In a conventional lead-acid battery with vented caps, what are the ventilation holes in those caps for?
- In a bus, preventive maintenance of the braking system is essential because:
- In a combustion-engine vehicle with a manual gearbox, when you need to slow down and conditions permit, which practice helps efficient safe driving?
- On a bus with hydraulic power steering and a reservoir marked MIN and MAX, should you check that fluid level?
- What are ABS, ASR and ESP devices?
- When you take your bus for its periodic technical inspection, which document, among others, might the ITV station staff ask you for?
- To check a bus engine’s oil level using its dipstick, how should you position the vehicle?
- What is the purpose of the bleeder in a hydraulic braking circuit?
- In a liquid-cooled engine whose coolant pump is belt-driven, which fault in that drive can cause overheating?
- You drive a bus and intend to overtake a motorcycle outside a built-up area. Under the current general rule, what lateral clearance must you leave?
- An ordinary M2 or M3 urban bus is seven years old from its first registration. How often must it undergo its periodic roadworthiness test (ITV)?
- What function does the system that adapts engine power to the grip of the driving wheels (A.S.R.) perform?
- If the bus you are driving has an ABS system and, when carrying out an emergency braking manoeuvre, you notice the brake pedal starting to vibrate, what should you do?
- On a bus with hydraulically operated clutch controls, how should you identify that circuit’s fluid filling point?
- During a routine check, when should you measure bus tyre pressure to compare it with the recommended cold inflation pressure?
- If the bus's clutch is operated hydraulically, should you check the fluid level?
- Should you replace the engine intake air filter on your bus?
- If, when your bus undergoes a technical inspection, the result is 'unfavourable', giving a period of one month to repair it, during that time...
- Before driving a bus, it is advisable to check:
- In a combustion-engine vehicle, when traffic and road conditions allow, which driving style helps reduce fuel consumption?
- What is the broad lateral surface of the tyre visible between its tread and the area seated on the rim called?
- In rain with reduced grip, what rule should you follow when using the bus’s electric retarder?
- In a new tyre, the label image provides information about safety and environmental aspects. What information does this label include, among others?
- In a safe place, an adult is unresponsive and not breathing normally, and 112 has been called. If you are trained and able to give rescue breaths, what compression-to-ventilation sequence should you use for CPR?
- A bus has hydraulic power steering with a reservoir and level marks. Should the driver check its fluid?
- With the engine running, the red low-oil-pressure warning remains on, outside the instrument panel’s initial check. What does it warn of?
- How should the bus be positioned when you check the engine oil level?
- Is it mandatory to install an anti-start breathalyser (alcolock) in a bus that has a standardised "interface" for its installation?
- When choosing engine coolant for a vehicle, what must you consider?
- What is the function of the discharge valve in the pneumatic braking system?
- Which periodic check is part of maintaining the engine lubrication system?
- To park your bus correctly on a noticeable slope, you must know that, besides taking other measures, you should leave it chocked, and for this purpose you may use...
- At a bus’s periodic technical inspection, which document records its technical specifications and inspections?
- In a conventional charging system, the warning lamp works during its initial check and goes out when the engine starts. If it stays off with the engine running, what does it normally indicate?
- What is the name of the system responsible for controlling the entry and exit of gases inside the cylinders?
- Your bus's electrical system runs on 24 volts and is powered by two 12-volt batteries. How must these batteries be connected to each other?
- How must the light produced by the lamps of the lighting circuit be projected by the headlamp?
- In a diesel fuel circuit with a separate feed pump, which component carries fuel from the tank to the injection system?
- A steering fault in a D1 or D bus:
- Compared with driving on underinflated tyres, maintaining the manufacturer’s recommended pressure helps to...
- To compare tyre pressure with the manufacturer’s specified cold value, in what condition should the routine check be made?
- The part that closes off and protects the moving parts of the engine from underneath is called:
- Tyre inflation pressure lower than recommended by the manufacturer will cause:
- If the voltage needed to operate the starter motor is 24 volts, how will you connect two 12-volt batteries to achieve this?
- Which gas accounts for most tailpipe greenhouse-gas emissions when burning petrol or diesel?
- In an eddy-current electromagnetic retarder, which parts make frictional contact to produce its braking torque?
- The coolant pump is the component that forces the circulation of coolant between:
- In a conventional compression-ignition diesel engine, what is the condition of the air when fuel is injected to produce combustion?
- If your bus's steering is hydraulically assisted, should you check the fluid level of the system?
- Your heavy vehicle has an auxiliary electric retarder in addition to its service and parking brakes. What should you use it for, following the manufacturer’s instructions?
- You park a manual-transmission bus on a noticeable uphill slope and will leave your driving position. Besides stopping the engine, switching off the starting system and applying the parking brake, what must you do?
- You drive a heavy vehicle whose tachometer marks the recommended efficient operating range in green. Under normal conditions, with sufficient pulling power after the shift, what is advisable when selecting a higher gear?
- Insufficient tyre pressure on your bus causes:
- If you notice a major fault in the brakes or steering of a D1 or D bus, the correct action is to:
- What does the adjustment of the headlights on the lighting system consist of?
- Which oil temperature can contribute to low lubrication pressure by reducing its viscosity?
- At the same speed relative to the air and under the same conditions, which vehicle characteristics directly affect aerodynamic drag?
- You drive a bus and intend to overtake a motorcycle outside a built-up area. Under the current general rule, what lateral clearance must you leave?
- What is the main function of ABS during heavy braking?
- In a pneumatic braking system, what is the function of the relief valve that limits the maximum pressure of stored air?
- What does the ABS braking system achieve?
- What happens when a tyre has a low pressure level?
- What is the general maximum permitted mass of a three-axle articulated bus, excluding special propulsion-technology increments and other lower restrictions?
- Your heavy vehicle has an auxiliary electric retarder in addition to its service and parking brakes. What should you use it for, following the manufacturer’s instructions?
- On a bus with hydraulic power steering and a reservoir with minimum and maximum marks, should you check the fluid level following the manufacturer’s instructions?
- In a modern fuel-injected car, which practice avoids unnecessary fuel use when starting the engine?
- The oil that lubricates the turbocharger mechanism is...
- As a general rule, to provide traction when using snow chains on a bus, which wheels must they be fitted to?
- There is a flywheel at one end of the crankshaft. What is it used for?
- If we keep the tyres at the correct pressure, we will ensure that…
- If, when carrying out the periodic technical inspection of the bus, the result is unfavourable, the vehicle…
- If you keep your tyres at the correct pressure, what will you achieve?
- If a warning appears in a D1 or D bus indicating a major fault, the correct action is to:
- With the engine running, the warning light for minimum oil pressure in the lubrication circuit stays on. What does it indicate?
- During a routine check, when should you measure bus tyre pressure to compare it with the recommended cold inflation pressure?
- If you notice unusual noises or vibrations in a D1 or D bus, the prudent action is to:
- What is the maximum authorised mass per single driven axle of class II (interurban buses)?
- What are the ABS, ASR and ESP systems?
- In a diesel system with separate supply and injection pumps, which component takes fuel from the tank into the low-pressure supply circuit?
- In a four-stroke engine with wet-sump lubrication, where is the oil-collecting sump?
- In a conventional compression-ignition diesel engine, what is the condition of the air when fuel is injected to produce combustion?
- In a direct-injection internal combustion engine, where does the mixture form?
- What is the purpose of the bleeder in a hydraulic braking circuit?
- Where is the air filter located in a supercharged combustion engine?
- In a conventional drivetrain with a propeller shaft and crown wheel and pinion final drive, which mechanism provides a fixed reduction before the wheels in addition to the gearbox?
How to ace the mechanics and maintenance questions on the D licence
Mechanics and maintenance questions are usually among the highest-failure areas in the D licence exam. Each of the 126 exam-style questions here includes the options, the correct answer and an explanation of why it's correct.
The most effective way to master this topic is to alternate syllabus reading with question practice. Start by reading the full topic, then click into any question to study it in detail. Failed questions enter the smart-review queue until you master them.
Frequently asked questions about mechanics and maintenance on the D licence
- How many mechanics and maintenance questions are in the D licence question bank?
- Our exam-style question bank includes 126 mechanics and maintenance questions for the D licence. Each comes with the correct answer and explanation.
- How should I study mechanics and maintenance for the D licence exam?
- The D test has 20 questions. Use this bank to practise mechanics and maintenance with explanations, and combine topic review with full mock exams.
- What are the most common mechanics and maintenance mistakes?
- Three typical causes: 1) misreading prompts with decisive keywords ("always", "never", "except", "only", "at least") — they flip the correct answer; 2) switching correct answers in the final review due to self-induced doubt; 3) studying only by topic without full simulations, which penalises block-switching speed.
- How should I practise mechanics and maintenance to prepare for the D licence?
- Alternate three modes: first study the full topic syllabus; then practise the 126 exam-style mechanics and maintenance questions until you understand the logic of each; finally launch full D-licence simulations (20 questions, max 2 wrong) to train block-switching under pressure.