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Free Practice Questions for SOLAS Heavy Vehicle Mechanic

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Key Facts: SOLAS Heavy Vehicle Mechanic Exam

100

Practice Questions

OpenExamPrep

NFQ 6

Award Level (QQI Advanced Certificate Craft)

SOLAS / QQI

4 years

Apprenticeship Duration

SOLAS

7 phases

Programme Structure

SOLAS

No fee

Apprentices Paid Throughout

SOLAS

Ireland

Heavy Vehicle / HGV Craft

SOLAS

The SOLAS Heavy Vehicles Mechanics apprenticeship is Ireland's four-year, NFQ Level 6 craft programme for heavy goods vehicle technicians, administered by SOLAS with QQI certification. It is structured over seven phases (four on-the-job with the employer and three off-the-job in a training centre and colleges) and is assessed by modular multiple-choice and written theory examinations alongside practical and work-based assessments. There is no separate exam fee, and apprentices are paid throughout. Content spans diesel engines and fuel systems, transmission and driveline, full air brake systems, steering and suspension, electrical and electronics, hydraulics, diagnostics and workshop health and safety. This free prep includes 100 research-based practice questions with explanations and an AI tutor.

Sample SOLAS Heavy Vehicle Mechanic Practice Questions

Try these sample questions to review concepts for the SOLAS Heavy Vehicle Mechanic exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a four-stroke diesel engine, which event occurs during the compression stroke?
A.Air is drawn into the cylinder
B.Air is compressed and fuel is injected near top dead centre
C.Burnt gases are expelled through the exhaust valve
D.The piston is forced down by combustion pressure
Explanation: On the compression stroke the inlet and exhaust valves are closed and the rising piston compresses the trapped air to a high pressure and temperature. Fuel is injected near top dead centre, igniting by compression heat without a spark plug.
2Diesel fuel ignites in the cylinder primarily because of which condition?
A.A high-voltage spark from a glow plug
B.The high temperature of the highly compressed air
C.A carburettor mixing fuel and air before entry
D.Ultraviolet light from the injector
Explanation: Diesel engines are compression-ignition engines. Compressing the air to roughly a 16:1 to 22:1 ratio raises its temperature well above the fuel's auto-ignition point, so injected fuel ignites spontaneously.
3What is the main purpose of a turbocharger on a heavy diesel engine?
A.To cool the engine coolant
B.To force more air into the cylinders to burn more fuel and increase power
C.To reduce the engine's compression ratio
D.To filter particulates from the exhaust
Explanation: A turbocharger uses energy in the exhaust gas to drive a turbine that spins a compressor wheel, forcing a greater mass of air into the cylinders. More air allows more fuel to be burned, raising power and efficiency without increasing engine size.
4Why is an intercooler (charge-air cooler) fitted between the turbocharger and the inlet manifold?
A.To increase the temperature of the boost air
B.To cool the compressed boost air, increasing its density
C.To lubricate the turbocharger bearings
D.To filter the air before the turbo
Explanation: Compressing air in the turbocharger heats it and lowers its density. The intercooler removes heat from the charge air so a denser, oxygen-richer charge enters the cylinders, improving combustion and reducing NOx formation.
5In a modern common-rail diesel injection system, what controls the exact timing and quantity of fuel delivered to each injector?
A.A mechanical inline pump driven by the camshaft
B.The engine ECU energising electronically controlled injectors
C.Engine vacuum acting on a diaphragm
D.The driver's accelerator cable directly opening the injectors
Explanation: Common-rail systems hold fuel at high pressure in a shared rail. The engine ECU commands solenoid or piezo injectors to open for precise durations and timings, allowing multiple injection events per cycle for better combustion, lower emissions and quieter running.
6Approximately what rail pressure can a modern heavy-vehicle common-rail diesel system reach?
A.Around 5 bar
B.Around 50 bar
C.Around 250 bar
D.Up to around 2,000-2,500 bar
Explanation: Modern common-rail systems operate at very high pressures, commonly up to about 2,000-2,500 bar (roughly 29,000-36,000 psi). Such high pressure produces very fine atomisation for cleaner, more complete combustion.
7What is the function of a glow plug in a heavy diesel engine?
A.To provide a spark to ignite the fuel
B.To pre-heat the combustion chamber to aid cold starting
C.To pressurise the fuel rail
D.To meter the air entering the cylinder
Explanation: A glow plug is an electric heating element that warms the combustion chamber (or pre-combustion chamber) before and during cold starts. This raises chamber temperature so the injected fuel ignites reliably when the cold engine cannot otherwise reach auto-ignition temperature.
8Which engine component converts the reciprocating motion of the pistons into rotary motion?
A.The camshaft
B.The crankshaft
C.The flywheel ring gear
D.The rocker arm
Explanation: The crankshaft, driven through the connecting rods, converts the up-and-down (reciprocating) movement of the pistons into rotary motion at the output. Its throws and journals are balanced and supported in main bearings.
9A diesel engine's valve clearance (tappet gap) is too small. What is the most likely consequence?
A.The valves will open later and close earlier
B.The valves may be held slightly open, causing burnt valves and loss of compression
C.Increased valve-train noise but no other effect
D.The injection timing will advance
Explanation: Too little clearance can prevent a valve from seating fully, especially when hot and expanded. A valve held off its seat loses the seat's heat path, overheats and burns, and the cylinder loses compression. Correct clearance must be set to manufacturer specification.
10What does a low reading on an engine oil pressure gauge most commonly indicate?
A.Coolant level is too high
B.Worn bearings, a faulty oil pump, low oil level, or oil that is too thin
C.The air filter is blocked
D.The turbocharger is over-boosting
Explanation: Low oil pressure results from reduced resistance to flow or insufficient supply: worn main/big-end bearings with large clearances, a worn or failing oil pump, low oil level, a stuck-open relief valve, or oil thinned by fuel dilution or overheating. It demands immediate investigation to avoid bearing failure.

About the SOLAS Heavy Vehicle Mechanic Exam

The SOLAS Heavy Vehicles Mechanics apprenticeship is Ireland's four-year, standards-based craft apprenticeship for technicians who service, diagnose and repair trucks, buses and other heavy goods vehicles. It runs over seven phases (four on-the-job with the employer and three off-the-job in training centres and colleges) and leads to a QQI Advanced Certificate Craft at NFQ Level 6. Off-the-job phases are assessed by modular multiple-choice and written examinations covering engines, fuel, transmission, brakes, electrics and more.

Exam sponsor: SOLAS (Further Education and Training Authority) with QQI certification. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Modular multiple-choice and written theory examinations taken during the off-the-job phases (Phase 2, 4, 6), plus practical skills and work-based assessments, leading to a QQI Advanced Certificate Craft at NFQ Level 6; this practice bank is 100 selected-response items across the core craft topics

Time Limit

Varies by phase examination

Passing Score

Typically 50%-60% per phase module (set by SOLAS/QQI)

Exam / Certification Fees

No separate exam fee for registered apprentices; apprentices are paid throughout the programme

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

25%

Diesel Engines & Fuel Systems

Compression-ignition cycle, common-rail injection, turbocharging, cooling and lubrication, EGR/SCR/DPF emission control and engine fault diagnosis

14%

Transmission & Driveline

Clutches, manual and automated gearboxes, range-change/splitter units, propeller shafts, universal joints, differentials and diff locks

13%

Braking & Air Systems

Air brake systems, compressor and governor, air dryer, S-cam brakes and slack adjusters, spring chambers, relay/protection valves, ABS and trailer couplings

10%

Steering & Suspension

Wheel alignment, power steering, kingpins, steel and air suspension, shock absorbers, anti-roll bars and wheel security

14%

Electrical & Electronics

24 V systems and batteries, Ohm's law and circuit testing, charging and starting, fuses, relays, sensors, diodes and CAN bus

8%

Hydraulics & Pneumatics

Pascal's principle, pumps, rams, relief valves, force calculations, contamination control and high-pressure fluid safety

6%

Diagnostics & Fault Finding

Logical diagnosis, diagnostic trouble codes and scan tools, compression and circuit testing, intermittent-fault tracing and repair verification

10%

Health & Safety

Safety, Health and Welfare at Work Act 2005, safe isolation, battery/brake-dust hazards, split-rim safety, manual handling, fire safety, PPE and waste disposal

Preparing for the SOLAS Heavy Vehicle Mechanic Exam

What You Need to Know

  • Passing score: Typically 50%-60% per phase module (set by SOLAS/QQI)
  • Assessment: Modular multiple-choice and written theory examinations taken during the off-the-job phases (Phase 2, 4, 6), plus practical skills and work-based assessments, leading to a QQI Advanced Certificate Craft at NFQ Level 6; this practice bank is 100 selected-response items across the core craft topics
  • Time limit: Varies by phase examination
  • Exam / certification fees: No separate exam fee for registered apprentices; apprentices are paid throughout the programme Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

SOLAS Heavy Vehicle Mechanic: Suggested Study Strategy

1Weight your study toward diesel engines and fuel systems and the air brake system, which together make up the largest share of the craft content
2Memorise key air-brake values: governor cut-out around 120-130 psi and spring brakes applying below about 60 psi when air is lost
3Know your emission systems cold: EGR lowers combustion temperature for NOx, the DPF traps soot and regenerates, and SCR injects 32.5% urea AdBlue to cut NOx
4Practise Ohm's law (I = V / R) and force = pressure x area for the electrical and hydraulic calculation questions
5Learn the diesel smoke colour code (black = over-fuelling, blue = burning oil, white/grey = unburnt fuel or coolant) for fault-finding questions
6Complete all 100 practice questions and review every miss with the AI tutor before your phase examinations

Frequently Asked Questions

How is the SOLAS Heavy Vehicle Mechanics apprenticeship assessed?

It is a four-year, standards-based craft apprenticeship assessed over seven phases. The off-the-job phases (Phase 2, 4 and 6) use modular multiple-choice and written theory examinations together with practical skills and work-based assessments, leading to a QQI Advanced Certificate Craft at NFQ Level 6.

How many questions are in the SOLAS Heavy Vehicle Mechanic exam?

SOLAS does not publish a single fixed question count. Each off-the-job phase is assessed by modular multiple-choice and written examinations, so the number of questions varies by module and phase. Our practice bank gives you 100 questions across all the core craft topics.

What topics does the heavy vehicle mechanic apprenticeship cover?

Core areas are diesel engines and fuel systems, transmission and driveline, air brake systems, steering and suspension, electrical and electronics, hydraulics, diagnostics, and workshop health and safety, all to NFQ Level 6 craft standard.

What qualification do I get and at what level?

Successful apprentices are awarded a QQI Advanced Certificate Craft in Heavy Vehicle Mechanics at NFQ (National Framework of Qualifications) Level 6, a recognised craftsperson qualification in Ireland.

Is there a fee to sit the apprenticeship exams?

There is no separate exam fee for registered apprentices. Apprentices are paid a wage throughout the programme, and the off-the-job training phases are State-funded through SOLAS and the education providers.

Is this free SOLAS Heavy Vehicle Mechanic practice as good as paid prep?

Our 100 practice questions cover the same craft topics as the apprenticeship phase examinations, with a teaching explanation for every answer plus free daily AI tutor interactions. All content is free forever and updated for 2026.