Vehicle technology: engine, fluids, fuel, electrics, drivetrain, troubleshooting, maintenance
How the diesel engine, turbocharger, fuel and SCR system, electrics and drivetrain work, and how to interpret important warning lights. Also systematic troubleshooting, preventive maintenance and the rules on vehicle condition, exhaust maintenance and periodic inspection.
- 52 questions in this topic
- Topic 10 of 16 in the course: Bus & Coach – supplementary theory cat. D and D1
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From the key facts
- Before driving, the driver checks that the vehicle and load comply with the rules; minor defects en route: continue with care, repair without delay (VRV Art. 57 para. 1 and 3).
- Red warning lights (oil pressure, coolant temperature, brake) require an immediate stop; yellow lights indicate faults or information to be dealt with promptly.
All key facts, the questions with explanations and the exam simulation are part of the course.
Sample questions from this topic
3 of 52 questions free to try. All questions with explanations and the exam simulation are part of the course.
Question 1: How is the fuel ignited in a diesel engine?
- By spark plugs in each cylinder
- By the air heated during compression
- By glow plugs that glow continuously while driving
Show answer
Correct answer: By the air heated during compression
The diesel engine compresses air so strongly that it becomes very hot; the injected fuel ignites on it by itself. Petrol engines have spark plugs. Glow plugs or an intake air heater only help with cold starts.
Legal reference: Practice (generally recognised); VZV Annex 11 no. II.2.11
Question 2: What is the function of the turbocharger?
- It uses exhaust energy to compress the intake air.
- It delivers the fuel at high pressure to the injectors.
- It cools the engine oil under high load.
Show answer
Correct answer: It uses exhaust energy to compress the intake air.
In the turbocharger, the exhaust flow drives a turbine which turns a compressor via a shaft. This forces more air into the cylinders so that more fuel can be burnt and more power produced. Fuel delivery and oil cooling are other assemblies.
Legal reference: Practice (generally recognised); VZV Annex 11 no. II.2.11
Question 3: What is the intercooler used for?
- It cools the air of the air conditioning in the driver's cab.
- It cools the intake air compressed by the turbocharger.
- It cools the exhaust gases before they enter the particulate filter.
Show answer
Correct answer: It cools the intake air compressed by the turbocharger.
When compressed in the turbocharger, the air heats up. The intercooler cools it down again; cooler air is denser and contains more oxygen for combustion. It has nothing to do with exhaust or cab cooling.
Legal reference: Practice (generally recognised)
Legal references for this topic
The questions in this topic are based on these provisions:
- VTS Art. 35, 36, 49, 50, 52, 54, 80, 81, 97
- VRV Art. 33, 57, 59, 59a, 59b, 59c
- VZV Annex 11, Annex 12