DGT C1 licence questions: Mechanics and maintenance

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Question index View topic Practise Mechanics and maintenance

When approaching a foreseeable stop, if conditions allow safe deceleration, what helps save fuel in a combustion-engine vehicle?
In a lorry’s friction clutch with a manual gearbox, which component is pressed against the flywheel to transmit engine rotation to the…
Should you periodically check the level of the windscreen washer fluid?
Stopping distance when braking for a hazard is the sum of...
In a conventional four-cylinder, four-stroke engine, how far does the crankshaft rotate during one complete piston stroke from one dead…
If your lorry’s engine takes too long to reach normal operating temperature, which component should be checked?
A lorry is driven at night, with good visibility and no conditions permitting fog-light use. May it travel with position lights alone?
By definition, a heated lorry is a motor vehicle that is:
A lorry circuit requires nominal 24 V and has two compatible 12 V batteries. Which connection adds their voltages?
When overtaking a car with a lorry, what safe lateral separation must be left?
Before driving a truck, which option includes checks of its safety systems rather than only fuel or cleanliness?
In a combustion-engine vehicle with electronic injection that does not require accelerator input to start, which practice avoids…
In a lorry with a liquid-cooled combustion engine, the engine takes abnormally long to reach operating temperature. Which component…
If, due to traffic conditions, a lorry with an MAM (maximum authorised mass) of more than 3,500 kg becomes stationary inside an underpass,…
In a liquid-cooled engine whose coolant pump is belt-driven, which fault may reduce coolant circulation and cause overheating?
What benefit is supported by keeping lorry tyres at the recommended cold pressure for their load?
If, due to traffic requirements, a truck with a maximum authorised mass (MAM) of more than 3,500 kg becomes immobilised inside an…
What is the “fading” effect that a vehicle's brakes can suffer from?
If a vehicle's steering system shows unstable behaviour and pulls to one side, what should we check?
If, when operating the direction indicator, the warning lamp flashes faster than normal, this indicates that...
If a warm engine persistently emits bluish exhaust smoke, what may this indicate?
Under the conventional arrangement described in the DGT mechanics manual, where is the engine cooling-system thermostat generally located?
Other conditions being equal, how may tyre pressure below the recommendation for the load affect fuel consumption?
A driver without specialist training should leave replacement of certain lamps to a workshop because of high-voltage risk. Which lamps does…
The driver of a lorry with a MAM exceeding 3,500 kg must leave the driving position when parking on a steep upward slope with a kerb. If…
In a hydraulic braking system, the pedal feels spongy and temporarily improves after repeated applications. Which of these may be a cause…
What does the aiming (adjustment) of a lorry's headlights consist of?
If you notice a major fault in the brakes or steering of a C1 or C truck, the correct action is to:
A combination of vehicles consisting of a motor vehicle coupled to a semi-trailer is known as:
Should I regularly check the windscreen washer fluid level?
One of the factors that affects driving safety is...
On a vehicle with a hydraulically actuated clutch, where should fluid level be checked following manufacturer instructions?
The engine oil dipstick is used to check...
What does the word “TUBELESS” written on the side of the tyre indicate?
In a cooling circuit designed to operate under pressure, what effect does increased pressure have on the boiling temperature of the same…
Between sunset and sunrise, you drive a lorry on a sufficiently lit road through a built-up area. Besides position lights, which headlights…
If you are driving your lorry downhill, can you put it in neutral to save fuel?
An electrical accessory does not work while the others operate normally. The manual says to check its overcurrent protection first. Which…
The vehicle ahead clearly signals that it will turn left. May a lorry overtake it on the right if there is enough space and the manoeuvre…
If an exhaust silencer is broken and no longer properly attenuates engine noise, what effect does this have?
When the shock absorber deteriorates and loses effectiveness over time, how does this affect the suspension?
After passing through a puddle, your lorry’s brakes may be wet. When it is safe to check, which operation should you verify especially?
A steering fault in a C1 or C truck:
Fog significantly reduces visibility. In addition to the compulsory position lights, may you use dipped headlights without switching on the…
What does the word 'tubeless' mean on a tyre?
In a vehicle with a manual gearbox and a working conventional pedal clutch, when is the clutch engaged, coupling the engine to the gearbox…
If your vehicle is fitted with a petrol engine and has a catalytic converter in the exhaust, what fuel should you use?
In a worm-gear steering system, how does the steering wheel return to its rest position (straight-ahead line)?
What does the word TUBELESS printed on the side of the tyre mean?
In a conventional manual gearbox and bevel-gear differential, what lubricant is normally used for the gears, respecting each unit’s…
Your lorry has a coolant expansion tank marked MIN and MAX. Under the manufacturer’s specified checking conditions, how should you check…
A heavy lorry has a working electric retarder. On a steep descent with adequate grip and use permitted by the manufacturer, how should it…
When the windscreen washer reservoir is low, how should you replenish it?
Which statement about braking distance on an icy road compared with a dry road at the same speed is correct?
When checking a lorry’s engine oil level with the dipstick under manufacturer instructions, on what ground should it be parked?
What is the function of the oil filter?
In a lorry with pneumatic brakes equipped with an air dryer, which device removes moisture from compressed air to reduce the risk of…
If the lorry I am driving has a hydraulically operated braking circuit, I must...
In a conventional system whose coolant pump is belt-driven from the engine, which component supplies movement to that belt?
Passive safety systems are...
On a road surface in good condition, the steering wheel vibrates particularly at certain speeds. Which of these mechanical causes may…
At the same speed and with the same vehicle, a wet road reduces grip compared with a dry road. What happens to braking distance?
When driving a vehicle with a manual gearbox and clutch pedal, what helps avoid unnecessary transmission wear?
What does adjusting the headlights of your lorry's lighting system involve?
With a small tread puncture where the object remains embedded, which tyre usually loses air more slowly than a tyre with an inner tube?
You park a 4,000 kg MAM lorry on a significant uphill gradient and leave the seat. In addition to stopping the engine, disconnecting the…
If you keep your vehicle's tyres at the correct pressure, you will ensure that...
What properties should a gearbox gear lubricant have?
Which gas is produced by complete combustion of the carbon in petrol or diesel fuel?
In a flooded lead-acid battery with vented caps, what are the vent openings for?
A lorry has an operational electric retarder and descends a steep gradient with suitable grip. Under manufacturer instructions, how should…
For efficient driving of a vehicle with a working synchromesh manual gearbox whose manufacturer does not require double-clutching, how…
As a general rule, stopping on urban roads shall be carried out by positioning the vehicle…
What does the pressure gauge in the lubrication system indicate?
One of the components that forms part of the pneumatic braking system is...
When checking engine oil level with a dipstick, what conditions should you follow?
What type of oil is a lubricant classified SAE 15W-40?
A lorry travels at night, between sunset and sunrise, on an insufficiently lit road through a built-up area. Which lights must it use?
How is the normal operating temperature of an engine’s coolant determined?
What should I do to drive efficiently?
An insulated lorry uses a cold source other than mechanical compression or absorption equipment to lower and maintain its internal…
If my lorry's steering is hydraulically assisted, should I check the steering fluid level?
Among the different systems that make up a vehicle's engine, which one does the catalytic converter belong to?
What is a lubricating oil with SAE 15W-40 specification?
When driving on a stretch of road that is flooded with water, what consequences can a shock absorber in poor condition have?
What risk does brake overheating from excessive use, for example on a long descent, create?
In a diesel engine with a conventional mechanical injection pump and rack-controlled fuel delivery, which assembly includes the governor…
Under comparable conditions and as a general rule, tyre grip is usually lower when driving on…
In an electrical diagram with two identical compatible 12 V nominal batteries suitable for series connection, which link gives 24 V nominal…
Light rain does not significantly reduce visibility. There is no fog, smoke, dust or other visibility-reducing condition, and you are not…
When parking a vehicle with a trailer on a noticeable uphill gradient and leaving the driving position, a suitable kerb is available but no…
In a serviceable flooded lead-acid battery, the level has fallen through normal water loss during use. Following manufacturer instructions,…
In a lorry with a synchronised manual gearbox, does unnecessary double-declutching with extra throttle blips and slower shifts support…
On a lorry with hydraulic power steering and a reservoir marked MIN and MAX, should you check its fluid level?
What main function do road-tyre tread grooves serve on a wet road?
If a road vehicle’s tyres, when cold, have less pressure than specified by the manufacturer for its load and use...
At the same speed, which driver-related factor can increase the distance travelled from perceiving danger until braking begins?
While driving your lorry, you notice that it veers towards one side of the carriageway only when you press the brake pedal. What could this…
In an internal-combustion engine, what does persistent bluish-white exhaust smoke associated with high oil consumption usually indicate?
At the same speed and with the same lorry, a wet road reduces grip compared with a dry road. If you do not intend to overtake, how should…