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Maseno University *

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Mechanical Engineering

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Nov 24, 2024

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©2023 TVET CDACC AUTOMOTIVE ARTISAN LEVEL 4 ENG / CU/AUT/CR/2/4/A Service and repairing vehicle engines July/August 2023. Time: 3 Hours TVET CURRICULUM DEVELOPMENT, ASSESSMENT AND CERTIFICATION COUNCIL (TVET CDACC) WRITTEN ASSESSMENT ASSESSOR’S GUIDE ASSESSOR INSTRUCTIONS Award marks as per the guidelines. This guide consists of twelve (4) printed pages. Page 1 of 5
©2023 TVET CDACC Assessor should check the guide to ascertain that all the pages are printed as indicated and that no questions or answers are missing . SECTION A (10 Marks) Note to assessor: These are suggested answers to act as guidelines ( Award any 1 mark for any correct answer ) Attempt ALL questions in this section (each question carries 1mk) 1. Which of the following is a four-stroke engine cycle sequence A. Intake, compression, power, exhaust B. Compression, power, intake, exhaust C. Power, exhaust, intake, compression D. Exhaust, intake, compression, power 2. What is the purpose of the radiator in a vehicle engine? A. Ignition B. Cooling C. Lubrication D. Exhaust 3. What fuel is commonly used in gasoline engines? A. Diesel B. Petrol C. Natural gas D. Propane 4. Which component is responsible for igniting the air-fuel mixture in a gasoline engine? A. Spark plug B. Fuel injector C. Carburettor D. Camshaft 5. What is the function of the crankshaft in an internal combustion engine? A. To regulate fuel flow B. To convert reciprocating motion to rotational motion C. To control air intake D. To compress the air-fuel mixture Page 2 of 5
©2023 TVET CDACC 6. In a diesel engine, how is ignition achieved? A. Spark ignition B. Compression ignition C. Electric ignition D. Turbo ignition 7. Which of the following is a common method for reducing emissions in vehicles? A. Increasing fuel consumption B. Using leaded gasoline C. Catalytic converters D. Removing mufflers 8. What is the purpose of the transmission in a vehicle? A. To provide power to the wheels B. To steer the vehicle C. To control engine temperature D. To change speed and torque 9. What does ABS stand for in the context of automotive technology? A. Automatic Brake System B. Anti-Brake Skid C. Accelerated Braking System D. Automated Brake Suspension 10. What type of engine is commonly used in most modern automobiles? A. Steam engine B. gas turbine engine C. Electric engine D. Internal combustion engine Page 3 of 5
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©2023 TVET CDACC SECTION B (60 MARKS) Note to assessor: These are suggested answers to act as guidelines Answer ALL questions in this section 1. Define the term "compression ratio (2marks) Measure of the degree of compression of the air-fuel mixture within the engine's combustion chamber before it is ignited 2. Explain the function of the alternator in a vehicle? (2marks) The main role of an alternator is to convert mechanical energy into electrical ene rgy 3. What is the role of the spark plug in a gasoline engine? (2marks) Ignition of Air-Fuel Mixture in the engine 4. What is the main purpose of the throttle body in a fuel-injected engine? (2marks) Regulate the amount of air that enters the engine. Here are the key functions of the throttle body : 5. Explain the purpose of the starter motor in an engine (4marks) Turning the engine over during ignition 6. What safety feature does ABS (Anti-lock Braking System) provide in a vehicle, (4marks) Prevent wheel lock-up during braking and enhance vehicle control under heavy braking or emergency 7. Differentiate direct injection from a carburetted injection in fuel delivery? (4marks) In carburetted systems, fuel and air are mixed outside the engine in the carburettor while In direct injection systems, fuel is injected directly into the combustion chamber of each cylinder . 8. Describe the difference between a two-stroke and a four-stroke engine (4marks) Two-stroke engine Completes one power cycle in two strokes of the piston while four-stroke engine completes one power cycle in four strokes 9. Describe the role of a spark plug in a gasoline engine (4marks) The primary function of a spark plug is to produce a high-voltage spark that ignites the compressed air-fuel mixture within the engine's combustion chamber . 10. State any fours symptoms of a bad spark plug (4marks) Page 4 of 5
©2023 TVET CDACC A. Misfiring: B. Poor Fuel Economy: C. Increased Emissions: D. Engine Knocking or Pinging: E. Difficulty Starting the Engine: F. Poor Engine Idling G. Any other correct response 11. State any 4 potential consequences of a timing belt failure? (4marks) A. Engine Stalling B. Valve and Piston Collision: C. Bent or Broken Valves: D. Piston and Cylinder Head Damage: E. Engine Damage: F. Any other correct response 12. State and explain the function of any two engine components (4marks) Any 2 correct answer s THIS IS THE LAST PRINTED PAGE Page 5 of 5