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?

At least one driven wheel on each side. On at least one driven wheel on each side of the vehicle. Driven-axle location depends on the vehicle; always choosing front or rear is insufficient. Use compatible chains and follow manufacturer instructions for wheels, fitting and limitations. This question concerns the chain option; Article 12.5.2 also permits special tyres subject to its requirements. The minimum rule does not replace other applicable instructions or restrictions.

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?

External rolling noise level. The EU label provides information including rolling resistance (related to fuel efficiency), wet grip and external rolling noise. External noise is different from noise inside the passenger compartment. The label does not provide average service life in extreme environments or a list of recyclable materials.

In a lorry with a transmission-mounted hydraulic retarder, which wheels receive its retarding effect?

To the driven wheels through the transmission. To the driven wheels through the transmission. The hydraulic retarder creates resistance to rotation using oil between its rotor and stator. It helps control speed and reduces service-brake use; it does not work by cutting fuel injection and does not replace the service brake for every braking need. Use it according to manufacturer instructions and grip conditions.

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?

In the expansion tank. In the expansion tank, checking that the level is between the indicated marks, normally with the engine cold. Do not open a cooling-system cap while hot: pressurised coolant can cause burns. Use the specified coolant and seek workshop advice if the level repeatedly falls. The thermostat regulates coolant flow to the radiator according to temperature; it is not where the level is measured.

Mechanics and maintenance - D Licence

Step 1. The big picture

A person wearing reflective clothing inspects a front wheel of a green bus parked in a parking bay. — Bus inspection before driving

In one sentence…

Preventive maintenance of buses and minibuses is part of road safety: it prevents breakdowns, reduces braking distance, improves stability and cuts down on exam and real-driving errors. On the D licence you must treat it as part of your routine as a driver, not as a task left to the garage.

What you'll cover

1.Checks before setting off
2.Tyres, brakes and stability
3.Lights and optical signalling
4.Preparing the driving position
5.Load, luggage and trailer
6.Maintenance and efficient driving
7.How to practise this topic

Step 2. The syllabus

2.1Checks before setting off

Before demanding use or a long journey, check the tyres, pressure, tread, uneven wear, lights, optical signalling and general condition of the brakes.

Check essential levels whenever the vehicle requires it: oil, coolant, brake fluid and windscreen washer fluid, because they affect safety and visibility.
Check doors, locks, mirrors, wipers and dashboard warning lights before starting the service, especially if another driver used the vehicle before you.
If you find a defect affecting an essential component, do not treat it as a minor nuisance: it affects braking, stability, visibility and passenger safety.

2.2Tyres, brakes and stability

Tyres provide the actual contact with the road; pressure, tread and uneven wear alter grip, braking and cornering response.

A braking system in poor condition lengthens stopping distance and can turn a manoeuvre that is correct on paper into an insufficient one in a real situation.
In buses, mass, height and internal weight distribution mean that any wheel or brake defect is felt more when braking, turning or avoiding an obstacle.
The exam usually presents defects as safety problems, not as isolated mechanical vocabulary; always link the defect, its consequence and the prudent conduct.

2.3Lights and optical signalling

Lights and indicators let you see, be seen and signal manoeuvres; a faulty bulb can make an action that would be normal with full visibility dangerous.

Check indicators, position lights, dipped beam, brake lights and hazard lights with a service mindset: other road users need enough time to understand what the vehicle will do.
In passenger transport, stopping, pulling away or a slow manoeuvre needs clear signalling to protect passengers and other road users.
Do not memorise lighting as a closed list; think about how each light communicates presence, intent, width or a reduction in speed depending on the situation.

2.4Preparing the driving position

The DGT requires you to know how to prepare the vehicle for safe driving: seat, mirrors, seatbelt, doors and basic checks of the general condition.

Adjusting the driving position avoids correcting your posture while under way and improves control of the sides, the near front and tracking the bodywork.
Preparation also includes checking that the passenger compartment has no loose objects that could shift, distract the driver or affect the passengers.
In the exam, a question about the seat or mirrors is not about comfort; it tests whether you understand how poor preparation reduces observation and reaction time.

2.5Load, luggage and trailer

If the vehicle is towing a trailer or carrying a load, check the couplings, locks, electrical connections and balanced weight distribution before setting off.

Badly placed luggage can interfere with exits, stability or interior safety, which is why controlling it is part of the vehicle's operational maintenance.
An unbalanced load changes how the vehicle responds when braking, cornering or performing a slow manoeuvre, even when the driver applies correct technique.
When the exam mentions load or a trailer, first identify which element could fail: anchoring, connection, lights, weight distribution, locking or interference with passengers.

2.6Maintenance and efficient driving

Correct pressure, wheel alignment, filters in good condition and a reasonable load reduce fuel consumption and wear without changing the main safety obligation.

Smooth driving helps, but it does not make up for a known defect in the brakes, wheels, lights or interior safety features.
Driving with a known defect can be a reportable offence if it affects essential vehicle components; the prudent decision is to fix it before providing the service.
Efficiency is studied alongside safety because a well-maintained vehicle responds predictably and avoids unnecessary mechanical strain.

2.7How to practise this topic

Turn every check into a cause-and-effect question: what am I checking, what risk does it prevent, and what would I do if I found a fault.

When reviewing practice questions, note whether the correct answer relies on passenger safety, visibility, braking, stability or load control.
Do not limit yourself to the engine; on passenger-transport licences, wheels, brakes, lights, doors, mirrors, fixings and interior features are just as examinable.
If an answer proposes continuing to drive despite an essential defect, be suspicious: the exam standard usually rewards stopping, checking or fixing before continuing.

Step 3. Key points

If you only have a minute before the exam, revise this.

1.Check tyres, pressure, tread and wear before demanding services.
2.Check brakes, lights, indicators and wipers before setting off.
3.Adjust the seat, mirrors and seatbelt before pulling away.
4.Check essential levels whenever the vehicle requires it.
5.Check doors, locks, luggage and loose objects in the passenger compartment.
6.Link each defect to its effect on braking, stability or visibility.
7.Fix any fault that affects essential components before the service.
8.Practise questions thinking about passenger safety, not only mechanics.

Step 4. Exam traps

Mistakes the DGT uses again and again on this topic.

Thinking maintenance is only a garage matter and not a road-safety matter.
Focusing on the engine and forgetting wheels, brakes, lights or fixings.
Believing that smooth driving makes up for a major mechanical defect.
Forgetting that badly placed luggage can also create risk inside the vehicle.
Treating a faulty light as a minor problem even though it prevents signalling manoeuvres.
Not linking tyre pressure and wear with braking and stability.

Step 5. Quick check

Four real exam questions on what you have just read.

Question 1/4

A 24 V starting system uses two identical compatible 12 V batteries. Which connection adds their nominal voltages?

Practise more mechanics and maintenance questions

Step 6. Frequently asked questions about mechanics and maintenance

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?: At least one driven wheel on each side. On at least one driven wheel on each side of the vehicle. Driven-axle location depends on the vehicle; always choosing front or rear is insufficient. Use compatible chains and follow manufacturer instructions for wheels, fitting and limitations. This question concerns the chain option; Article 12.5.2 also permits special tyres subject to its requirements. The minimum rule does not replace other applicable instructions or restrictions.See full question
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?: External rolling noise level. The EU label provides information including rolling resistance (related to fuel efficiency), wet grip and external rolling noise. External noise is different from noise inside the passenger compartment. The label does not provide average service life in extreme environments or a list of recyclable materials.See full question
In a lorry with a transmission-mounted hydraulic retarder, which wheels receive its retarding effect?: To the driven wheels through the transmission. To the driven wheels through the transmission. The hydraulic retarder creates resistance to rotation using oil between its rotor and stator. It helps control speed and reduces service-brake use; it does not work by cutting fuel injection and does not replace the service brake for every braking need. Use it according to manufacturer instructions and grip conditions.See full question
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?: In the expansion tank. In the expansion tank, checking that the level is between the indicated marks, normally with the engine cold. Do not open a cooling-system cap while hot: pressurised coolant can cause burns. Use the specified coolant and seek workshop advice if the level repeatedly falls. The thermostat regulates coolant flow to the radiator according to temperature; it is not where the level is measured.See full question

See all mechanics and maintenance questions

Mechanics and maintenance