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Maharashtra HSC NSQF Automotive Service Technician (G3) study materials
Maharashtra HSC NSQF Automotive Service Technician (G3) study resources

Maharashtra HSC NSQF Automotive Service Technician (G3) practice questions

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Question 1Automotive workshop safety, environment and 5S practices

In the 5S system used in an automotive service workshop, what does the first step 'Seiri' (Sort) require a technician to do?

  1. Separate needed tools and materials from unneeded ones and remove the unneeded items from the work area Correct answer.
  2. Arrange the most-used spanners at the front of the tool trolley for quick reach
  3. Assign one technician to inspect all fire extinguishers at the end of every shift
  4. Repaint the floor around each work bay with fresh yellow and white markings

Explanation

Seiri (Sort) is the first pillar of 5S and means identifying which items are actually required for the job and clearing everything else out of the bay. Only after unneeded items are removed can the remaining tools be positioned and standardised in later steps. Repainting, arranging and inspecting are activities that belong to later pillars or to separate safety routines.

Question 2Automotive workshop safety, environment and 5S practices

A technician must lift a gearbox from a floor pallet. Which practice best protects the lower back according to workshop manual-handling guidance?

  1. Hold the load at arm's length to keep it away from the clothing
  2. Twist the trunk while lifting so the load swings onto the workbench
  3. Keep the feet together and bend the spine forward to reach the load
  4. Bend the knees, keep the back straight and hold the load close to the body Correct answer.

Explanation

Safe manual handling keeps the natural curve of the spine, uses the strong leg muscles by bending the knees, and keeps the load close to the body to reduce the lever arm on the lower back. Twisting, stooping and reaching out all increase the compressive load on the lumbar spine. Heavy components such as a gearbox should ideally be moved with a trolley or hoist rather than by hand.

Question 3Automotive workshop safety, environment and 5S practices

Which fire extinguisher class is correct for a burning petrol spill on the workshop floor?

  1. Water (Class A) extinguisher
  2. Wet chemical (Class F) extinguisher
  3. Foam extinguisher approved only for Class A solids
  4. Carbon dioxide or dry powder (Class B) extinguisher Correct answer.

Explanation

Petrol is a flammable liquid and falls in Class B, for which CO2 and dry powder extinguishers are suitable. Water must never be used on burning fuel because it spreads the flaming liquid and can cause the fire to flash back. Class F wet chemical units are intended for cooking oils and fats, not for petroleum fuels.

Question 4Automotive workshop safety, environment and 5S practices

Why must a vehicle's negative battery terminal be disconnected first before any electrical work in the workshop?

  1. It is the only terminal that carries current when the ignition is off
  2. It resets the ECU so that fault codes are cleared automatically
  3. It stops the engine from idling during the repair
  4. It prevents accidental short circuits to the chassis, which is connected to the negative terminal Correct answer.

Explanation

On a negative-earth vehicle the chassis is bonded to the battery negative, so a spanner touching the positive terminal and any body panel would create a dead short. Disconnecting the negative terminal first removes that return path and protects both the technician and the vehicle electronics. The positive terminal is reconnected last when the work is complete.

Question 5Automotive workshop safety, environment and 5S practices

In the 5S system, which activity corresponds to 'Seiketsu' (Standardise)?

  1. Sweeping the workshop floor at the end of the shift
  2. Throwing away broken tools that have not been used for a year
  3. Creating written checklists and visual standards so the first three S steps are repeated consistently Correct answer.
  4. Putting labels on all storage bins for the first time

Explanation

Seiketsu means turning the earlier Sort, Set in order and Shine activities into documented routines, checklists and visual standards so they are maintained by everyone. It is about making good practice the normal way of working, not about a one-time clean-up. The other options describe the individual Sort, Shine and Set in order actions.

Question 6Automotive workshop safety, environment and 5S practices

What is the correct way to store a used oil filter after removal from an engine?

  1. Wash it with solvent and pour the solvent down the workshop drain
  2. Place it in the general workshop bin with other metal scrap
  3. Drain it into a labelled hazardous-waste container and store the drained filter in the designated used-filter drum Correct answer.
  4. Leave it on the floor under the vehicle until the end of the shift

Explanation

A used oil filter holds residual lubricating oil, which is a hazardous waste and must be drained and collected separately for authorised disposal or recycling. Mixing it with general scrap or leaving it on the floor creates a spill and pollution risk. Solvent washings must never enter the storm or sanitary drain.

Question 7Automotive workshop safety, environment and 5S practices

A technician notices a strong smell of solvent while working in a closed service bay. Which immediate action follows workshop safety practice?

  1. Light a match to check whether the vapour is flammable
  2. Continue working and open the bay door only when the job is finished
  3. Spray air freshener to mask the smell and carry on
  4. Stop work, ventilate the area and check that extraction or local exhaust ventilation is operating Correct answer.

Explanation

Solvent vapour is both a health hazard and a fire risk, so the area must be ventilated and the extraction system verified before work continues. Local exhaust ventilation at the source is the preferred control for solvent vapour. Masking the smell or testing with a flame creates serious danger.

Question 8Automotive workshop safety, environment and 5S practices

Which PPE combination is most appropriate when grinding a metal component on a pedestal grinder in the workshop?

  1. Loose overalls with open sleeves and no eye protection
  2. Welding helmet with dark filter lens and leather gauntlets
  3. Cotton gloves, sandals and a cotton apron
  4. Safety goggles, face shield, hearing protection and a dust mask Correct answer.

Explanation

Grinding produces flying particles, sparks, noise and fine metal dust, so eye and face protection, hearing protection and respiratory protection are all required. Gloves must not be worn near rotating grinding wheels because they can be caught and drag the hand into the machine. Loose clothing and open footwear add further entanglement and impact hazards.

Question 9Automotive workshop safety, environment and 5S practices

A trolley jack has been used to raise a car for a brake inspection. What must be done before the technician reaches under the vehicle?

  1. Lower the vehicle onto the jack and rely on the jack's hydraulic seal
  2. Chock only the front wheels and leave the jack holding the load
  3. Place axle stands under the vehicle's specified jacking points and lower the load onto them Correct answer.
  4. Ask a colleague to hold the jack handle steady while work is done

Explanation

A trolley jack is a lifting device, not a support device; hydraulic pressure can bleed off and the vehicle can drop. The vehicle must be supported on axle stands placed at the manufacturer's specified points before anyone goes underneath. Wheel chocks and a colleague holding the handle do not provide a positive mechanical support.

Question 10Automotive workshop safety, environment and 5S practices

A technician is about to use a two-post vehicle lift. Which check is most important before raising the vehicle?

  1. Ensure the vehicle doors are locked and the windows are closed
  2. Confirm the vehicle's centre of gravity is roughly between the posts and the lift pads contact the correct jacking points Correct answer.
  3. Check that the workshop radio is switched off
  4. Make sure the vehicle's fuel tank is completely full

Explanation

A two-post lift is stable only when the vehicle's centre of gravity lies between the posts and all four arms support the manufacturer's jacking points. Incorrect positioning can cause the vehicle to tip or slide off the lift. Fuel level, door locking and radio status have no bearing on lift stability.

Question 11Automotive workshop safety, environment and 5S practices

Which statement correctly describes the purpose of a Material Safety Data Sheet (SDS) kept in an automotive workshop?

  1. It lists the names of technicians who are authorised to use the product
  2. It provides hazard, handling, first-aid and disposal information for a specific chemical product Correct answer.
  3. It records the warranty period of every chemical purchased by the workshop
  4. It shows the retail price and supplier discount for each product

Explanation

An SDS is a standardised document that supplies information on the hazards, safe handling, storage, first-aid measures, fire-fighting and disposal of a chemical product. It must be readily accessible to workers who use or may be exposed to the substance. It does not record warranty, pricing or personnel authorisation details.

Question 12Automotive workshop safety, environment and 5S practices

A technician working with a lead-acid battery must add water to the cells. Which practice is correct?

  1. Check the level with a naked flame to see the electrolyte clearly
  2. Add concentrated sulphuric acid to top up the level
  3. Wear acid-resistant gloves and goggles, and add distilled water to the correct level Correct answer.
  4. Use tap water because the minerals help the electrolyte

Explanation

Battery electrolyte is dilute sulphuric acid, so acid-resistant gloves and eye protection are required when opening cells. Only distilled or demineralised water should be added to restore the level, because tap-water minerals contaminate the electrolyte. A flame near a battery is extremely dangerous because charging releases hydrogen gas.

Question 13Automotive workshop safety, environment and 5S practices

Which of the following is a correct procedure for handling a spill of engine oil on the workshop floor?

  1. Wash the oil into the floor drain with a hose
  2. Spread the oil thinly so that it evaporates faster
  3. Contain the spill with absorbent material, clean the area and dispose of the used absorbent as hazardous waste Correct answer.
  4. Cover the oil with a thin layer of sawdust and leave it permanently

Explanation

Oil spills must be contained and absorbed rather than washed away, because oil entering drains pollutes watercourses and may breach environmental regulations. The saturated absorbent is a hazardous waste and must go to an authorised disposal route. Leaving sawdust down or spreading the oil creates ongoing slip and fire risks.

Question 14Automotive workshop safety, environment and 5S practices

What is the main reason for using a fume extraction hose on the tailpipe when running an engine inside the workshop?

  1. To carry carbon monoxide and other exhaust gases outside so they do not accumulate in the work area Correct answer.
  2. To cool the exhaust system faster after a road test
  3. To reduce engine noise so technicians can talk
  4. To measure the exhaust gas temperature for the diagnostic report

Explanation

Exhaust gas contains carbon monoxide, which is colourless, odourless and potentially fatal in an enclosed space. A tailpipe extraction hose removes these gases to the outside atmosphere and protects everyone in the workshop. Noise reduction, cooling and temperature measurement are not the purpose of extraction.

Question 15Automotive workshop safety, environment and 5S practices

A technician is about to arc weld a chassis member in the workshop. Which control is essential to protect nearby workers from ultraviolet radiation?

  1. Turn up the workshop lighting so the arc looks less bright
  2. Lower the welding current to the minimum setting
  3. Erect welding screens or curtains around the welding area Correct answer.
  4. Ask colleagues to close their eyes while the arc is struck

Explanation

Arc welding emits intense ultraviolet radiation that can cause arc eye and skin burns in bystanders, so opaque welding screens or curtains must screen the work area. The welder also needs a proper welding helmet with the correct shade. Brightening the room or lowering current does not stop UV emission.

Question 16Automotive workshop safety, environment and 5S practices

Which of the following correctly matches a workshop waste to its disposal stream?

  1. Spent solvent collected in a labelled, closed hazardous-waste drum Correct answer.
  2. Scrap brake pads placed in the paper recycling bin
  3. Used coolant drained into the general rubbish bin
  4. Old tyres left outside the workshop gate for collection with domestic waste

Explanation

Spent solvent is a hazardous liquid waste and must be collected in a clearly labelled, closed container for authorised disposal. Coolant, brake pads and tyres all require specific waste streams and must not be mixed with general or domestic rubbish. Correct segregation prevents contamination and regulatory penalties.

Question 17Automotive workshop safety, environment and 5S practices

In 5S practice, what is the recommended way to mark the floor position of a movable engine hoist so that it is always returned to the same place?

  1. Rely on each technician to remember where the hoist was last used
  2. Write the hoist's name on a paper note stuck to the wall
  3. Paint a floor outline or marking in the designated location and label it clearly Correct answer.
  4. Store the hoist wherever there is free space at the end of the day

Explanation

Visual controls such as painted floor outlines and labels make the correct location obvious so that anyone can return the hoist to its designated place. This is the Set in order and Standardise aspect of 5S. Paper notes, memory and random storage fail once the workshop gets busy.

Question 18Automotive workshop safety, environment and 5S practices

A technician is asked to remove a fuel line on a petrol-injected vehicle before working on the engine. Which sequence best controls the fire and pressure hazard?

  1. Smoke a cigarette to test whether fuel vapour is present
  2. Cut the fuel line with a hacksaw to release the pressure quickly
  3. Relieve the fuel system pressure, disconnect the battery earth, then loosen the joint with a rag and a suitable container ready Correct answer.
  4. Loosen the joint while the engine is running so the pressure can escape safely

Explanation

Petrol injection systems hold residual pressure, so the pressure must be relieved and the battery earth disconnected before any joint is opened. A rag and a suitable container catch residual fuel and prevent it reaching hot surfaces or the floor. Working on a running engine, using a flame or cutting the line all risk a serious fire or injection injury.

Question 19Automotive workshop safety, environment and 5S practices

A workshop has a compressed-air line used for cleaning components. Which practice is most consistent with safe and environmentally responsible use?

  1. Use the air jet to blow brake dust off the assemblies into the open workshop air
  2. Direct the air jet at clothing to remove dust after the job
  3. Use the air jet at reduced pressure with a suitable extraction or wet method for dust, and never point it at skin Correct answer.
  4. Leave the air line pressurised and uncoupled on the floor between jobs

Explanation

Compressed air can drive brake dust, metal particles and bacteria into the air and even into the skin if it contacts the body. Dust from friction materials should be controlled with low-pressure air and extraction or a wet method. An uncoupled, pressurised hose is also a whipping hazard and wastes energy.

Question 20Automotive workshop safety, environment and 5S practices

During a risk assessment of a tyre-changing bay, which combination of controls best follows the hierarchy of control?

  1. Ask operators to stand further away during inflation without any other change
  2. Issue personal protective equipment and leave the inflation procedure unchanged
  3. Rely on a warning sign at the bay entrance as the only control
  4. Provide a tyre cage or restraining device for inflation, then train operators and enforce the use of eye protection Correct answer.

Explanation

The hierarchy of control places engineering controls such as a tyre inflation cage or restraining device above administrative measures and PPE. Training and enforcement then support the engineering control, and eye protection addresses residual risk. Signs, PPE or distance alone leave the hazard largely uncontrolled.

Question 21Hand tools, measuring instruments and workshop equipment

A technician needs to loosen a rusted 14 mm hex bolt on an exhaust bracket without damaging the head. Which tool is the most appropriate first choice?

  1. An adjustable wrench set to 14 mm
  2. A 14 mm six-point ring spanner Correct answer.
  3. A pair of slip-joint pliers
  4. A 14 mm open-end spanner

Explanation

A six-point ring spanner grips all six flats of the bolt head, so the load is spread and the risk of rounding a rusted fastener is lowest. It also allows a firm pull without slipping off.

Question 22Hand tools, measuring instruments and workshop equipment

On a metric outside micrometer, the thimble reads 12 divisions past the datum line and the barrel shows 7.5 mm. What is the measured reading?

  1. 7.12 mm
  2. 8.12 mm
  3. 7.50 mm
  4. 7.62 mm Correct answer.

Explanation

Each thimble division on a 0.01 mm micrometer equals 0.01 mm, so 12 divisions add 0.12 mm. Adding this to the 7.50 mm barrel reading gives 7.62 mm.

Question 23Hand tools, measuring instruments and workshop equipment

What is the main purpose of a torque wrench in engine assembly?

  1. To remove fasteners that are seized by corrosion
  2. To tighten a fastener to a specified clamping force Correct answer.
  3. To check the runout of a rotating shaft
  4. To measure the length of a fastener before fitting

Explanation

A torque wrench controls how much twisting force is applied so the fastener develops the clamping load the manufacturer specifies. Correct clamping prevents loosening, gasket leaks and thread or component damage.

Question 24Hand tools, measuring instruments and workshop equipment

A dial test indicator is mounted on a magnetic base to check brake disc runout. Which setup gives a valid reading?

  1. Stylus perpendicular to the disc face, base on a rigid non-vibrating surface Correct answer.
  2. Stylus at 45 degrees to the face, base held by hand
  3. Stylus resting on the disc edge, base clamped to the flexible brake hose
  4. Stylus touching the caliper body, base on the disc itself

Explanation

The stylus must contact the surface being measured at right angles so the reading reflects true axial movement. The base must sit on a rigid, stationary surface so vibration and flex do not add false readings.

Question 25Hand tools, measuring instruments and workshop equipment

Which instrument is designed to measure the internal diameter of a cylinder bore?

  1. Vernier height gauge
  2. Inside micrometer Correct answer.
  3. Feeler gauge
  4. Outside micrometer

Explanation

An inside micrometer has jaws that expand against the bore walls, so it reads internal diameter directly. Bore measurement also allows taper and ovality to be assessed when taken at several depths and directions.

Question 26Hand tools, measuring instruments and workshop equipment

A feeler gauge is the correct tool for which workshop task?

  1. Checking valve clearance with the engine cold Correct answer.
  2. Measuring piston ring end gap in the bore
  3. Checking crankshaft journal diameter
  4. Measuring cylinder head warpage

Explanation

A feeler gauge is a set of precision steel blades of known thickness used to check a gap by trial fit. Valve clearance is set by finding the blade that slides with slight drag at the specified clearance.

Question 27Hand tools, measuring instruments and workshop equipment

Why should a torque wrench be returned to its lowest setting after use?

  1. To prevent the handle from corroding in humid workshops
  2. To reset the ratchet direction for the next job
  3. To lock the scale so the setting cannot change
  4. To relieve spring tension and preserve calibration accuracy Correct answer.

Explanation

The internal spring stays compressed if the wrench is stored at a working setting, and over time this causes it to lose tension and drift out of calibration. Backing off to the lowest scale value protects the accuracy of the tool.

Question 28Hand tools, measuring instruments and workshop equipment

A technician must lift a removed gearbox weighing about 60 kg from the floor to a bench. What is the safest workshop practice?

  1. Drag the gearbox along the floor to the bench
  2. Use a suitable lifting device or get help rather than lifting alone Correct answer.
  3. Lift alone but keep the load away from the body
  4. Bend at the waist and lift quickly to save time

Explanation

A 60 kg load exceeds safe single-person manual handling limits, so a hoist, transmission jack or a two-person team should be used. Mechanical assistance removes the strain that causes back injury.

Question 29Hand tools, measuring instruments and workshop equipment

A hydraulic floor jack is used to raise a vehicle for underbody work. Which additional item is mandatory before anyone goes beneath it?

  1. Wooden blocks under the wheels only
  2. A trolley jack handle extension
  3. Rated axle stands placed under the chassis Correct answer.
  4. A second hydraulic jack on the opposite side

Explanation

A hydraulic jack can lose pressure or fail, so the raised vehicle must be supported on rated axle stands at the specified jacking points. The jack is a lifting device, not a support device.

Question 30Hand tools, measuring instruments and workshop equipment

A bench grinder is fitted with a new wheel. Which check must be done before starting the machine?

  1. Check that the tool rest is removed for clearance
  2. Spin the wheel by hand and listen for bearing noise
  3. Ring-test the wheel and confirm the rated speed exceeds the grinder speed Correct answer.
  4. Verify that the wheel guard has been removed for access

Explanation

A sound ring test detects cracks that could cause the wheel to burst, and the wheel's rated maximum speed must be at or above the machine speed. Both checks protect the operator from fragmentation injury.

Question 31Hand tools, measuring instruments and workshop equipment

A vernier caliper is used to measure the outside diameter of a valve stem. The main scale reads 6 mm and the vernier's 8th division aligns with a main scale line on a 0.02 mm caliper. What is the diameter?

  1. 6.16 mm Correct answer.
  2. 6.08 mm
  3. 6.40 mm
  4. 6.80 mm

Explanation

With a least count of 0.02 mm, the aligned vernier division is multiplied by 0.02, so 8 x 0.02 = 0.16 mm. Adding this to the 6 mm main scale reading gives 6.16 mm.

Question 32Hand tools, measuring instruments and workshop equipment

Which property makes a micrometer more suitable than a steel rule for measuring a crankshaft journal?

  1. A scale that is easier to read in poor light
  2. A longer measuring range in a single tool
  3. A lighter body that is easier to hold
  4. A resolution of 0.01 mm with a controlled measuring force Correct answer.

Explanation

Crankshaft journals have tight tolerance bands, so a tool reading to 0.01 mm is needed. The micrometer's friction thimble also applies a consistent measuring force, which prevents operator-induced variation.

Question 33Hand tools, measuring instruments and workshop equipment

A piston is measured at the skirt 90 degrees to the gudgeon pin axis. Why is this direction specified?

  1. The skirt is oval in the opposite direction to the bore wear
  2. Measuring across the pin axis gives the smallest diameter
  3. The pin axis is the only truly round part of the piston
  4. The skirt is relieved across the pin axis and is largest perpendicular to it Correct answer.

Explanation

Pistons are machined slightly oval, with the skirt relieved near the gudgeon pin bosses to allow for expansion and pin support. The specified measuring point perpendicular to the pin axis is therefore where the true running clearance is set.

Question 34Hand tools, measuring instruments and workshop equipment

What does the least count of a measuring instrument represent?

  1. The largest dimension the instrument can measure
  2. The smallest change in a measured value that the instrument can display Correct answer.
  3. The error introduced by temperature change
  4. The force applied by the measuring jaws

Explanation

Least count is the resolution of the instrument, meaning the smallest increment it can distinguish. For a vernier caliper with 50 divisions on a 49 mm vernier, this works out to 0.02 mm.

Question 35Hand tools, measuring instruments and workshop equipment

A hydraulic press is used to press a wheel bearing into a hub. Which practice protects both the bearing and the press?

  1. Press on the outer race when fitting the inner race
  2. Apply force only to the race being fitted and keep the ram aligned Correct answer.
  3. Strike the bearing with a hammer while the press holds it
  4. Overload the gauge briefly to seat the bearing faster

Explanation

Force must pass through the race that is being fitted so the rolling elements do not take the load and brinell the races. Keeping the ram aligned prevents side loading that can crack the bearing or bend the press.

Question 36Hand tools, measuring instruments and workshop equipment

During a compression test the gauge reading fluctuates and the needle will not settle. Which instrument fault is the most likely cause?

  1. A rubber hose that is too short
  2. A gauge body that is too heavy
  3. A leaking or sticky non-return valve inside the gauge Correct answer.
  4. A gauge scale marked in the wrong units

Explanation

A compression gauge holds the peak pressure with a small non-return valve, so a leaking or sticking valve lets pressure escape and the needle falls back. The result is a fluctuating reading that never settles on a stable value.

Question 37Hand tools, measuring instruments and workshop equipment

Which tool should be used to remove a stubborn wheel nut without damaging the wheel or the nut?

  1. A breaker bar with a correctly sized six-point socket Correct answer.
  2. A pipe wrench on the nut flats
  3. A cold chisel and hammer
  4. An open-end spanner of the nearest metric size

Explanation

A breaker bar gives high leverage through a six-point socket that fully surrounds the nut, so the load is spread over all flats. This removes tight nuts without rounding them or marking the wheel.

Question 38Hand tools, measuring instruments and workshop equipment

A workshop air impact wrench is rated at 700 Nm. Why should it not be used to finally tighten cylinder head bolts?

  1. Impact torque is uncontrolled and cannot guarantee the specified clamp load Correct answer.
  2. Impact sockets are not available in head bolt sizes
  3. Impact wrenches are too slow for a sequence of head bolts
  4. Impact wrenches cannot rotate in the tightening direction

Explanation

Cylinder head bolts require a defined torque, often followed by a torque-angle stage, to produce even clamping across the gasket. An impact wrench delivers uncontrolled hammering torque that cannot meet this specification and may over-stretch the bolts.

Question 39Hand tools, measuring instruments and workshop equipment

What is the function of a valve spring compressor in cylinder head work?

  1. To measure the free length of the valve spring
  2. To compress the valve spring so the retainer and collets can be removed Correct answer.
  3. To reface the valve seat angle
  4. To check valve stem straightness in the guide

Explanation

The compressor squeezes the spring so the split collets release from the valve stem groove and the retainer can be lifted off. The same tool is used to refit the spring and collets safely.

Question 40Hand tools, measuring instruments and workshop equipment

A technician compares a vernier caliper, an outside micrometer and a dial caliper for routine brake pad thickness checks. Which statement is the most defensible?

  1. The vernier caliper suits the task because 0.02 mm resolution is adequate and the jaws reach the pad Correct answer.
  2. All three are equally valid because resolution never matters
  3. The micrometer is best because its 0.01 mm resolution is always needed
  4. The dial caliper is unsuitable because it cannot measure thickness

Explanation

Brake pad wear limits are typically stated in whole or half millimetres, so 0.02 mm resolution is more than adequate and the caliper jaws reach into the caliper bracket easily. Choosing a tool also depends on access and the tolerance of the job, not resolution alone.

Question 41Automotive engine systems: construction, components and working principles

In a four-stroke petrol engine, during which stroke does the piston move from top dead centre to bottom dead centre with both valves closed?

  1. Power (expansion) stroke Correct answer.
  2. Intake (suction) stroke
  3. Exhaust stroke
  4. Compression stroke

Explanation

The power stroke begins just after ignition at TDC, when the burning charge drives the piston down to BDC. Both valves stay closed so the expanding gases push on the piston instead of escaping. This is the only stroke that delivers useful work to the crankshaft.

Question 42Automotive engine systems: construction, components and working principles

Which component converts the reciprocating motion of the piston into rotary motion of the crankshaft?

  1. Connecting rod Correct answer.
  2. Flywheel
  3. Push rod
  4. Camshaft

Explanation

The connecting rod links the piston pin to the crankpin and swings through an arc as the crank rotates. This geometry turns straight-line piston travel into rotation. The other parts either drive the valves or smooth out the rotation.

Question 43Automotive engine systems: construction, components and working principles

The swept volume of one cylinder is calculated using which pair of dimensions?

  1. Combustion chamber volume and compression ratio
  2. Cylinder bore and piston stroke Correct answer.
  3. Valve head diameter and lift
  4. Crankshaft radius and flywheel diameter

Explanation

Swept volume equals the cross-sectional area of the bore multiplied by the stroke length. Bore gives the area, and stroke gives the distance the piston travels. Together they define the displacement of each cylinder.

Question 44Automotive engine systems: construction, components and working principles

What is the main function of the flywheel in a single-cylinder four-stroke engine?

  1. It stores energy during the power stroke and releases it during the other strokes. Correct answer.
  2. It mixes fuel with air before the inlet valve.
  3. It filters the lubricating oil before it reaches the bearings.
  4. It opens the exhaust valve at the correct moment.

Explanation

In a single-cylinder four-stroke engine, only one stroke in four produces work, so rotation would be very uneven. The heavy flywheel absorbs surplus energy during the power stroke and gives it back during intake, compression and exhaust. This keeps the crankshaft turning smoothly between power impulses.

Question 45Automotive engine systems: construction, components and working principles

In a diesel engine, ignition of the fuel occurs because:

  1. the fuel is injected into air that has been heated by high compression Correct answer.
  2. a spark plug fires just before top dead centre
  3. a glow plug ignites the mixture on every stroke
  4. the exhaust valve opens early to create a flame front

Explanation

A diesel engine compresses only air to a high ratio, which raises its temperature well above the fuel's self-ignition point. Fuel injected near the end of compression ignites spontaneously. No external spark is needed.

Question 46Automotive engine systems: construction, components and working principles

Which part of the valve train directly opens the valve against spring pressure?

  1. Valve seat
  2. Valve stem seal
  3. Rocker arm Correct answer.
  4. Valve guide

Explanation

The rocker arm pivots on its shaft and pushes down on the valve stem tip, overcoming the valve spring. The spring then closes the valve when the rocker releases it. The guide and seat only locate and seal the valve.

Question 47Automotive engine systems: construction, components and working principles

The main purpose of the cooling system in a water-cooled automotive engine is to:

  1. raise the temperature of the incoming charge
  2. keep metal temperatures within a range that maintains clearances and oil film strength Correct answer.
  3. lubricate the camshaft bearings
  4. increase the compression ratio

Explanation

Combustion heats the head and block, and excessive temperature would distort parts, reduce clearances and break down the oil film. The cooling system removes surplus heat and holds the engine near its designed operating temperature. It does not change compression ratio or lubricate bearings.

Question 48Automotive engine systems: construction, components and working principles

Which engine layout places the cylinders in two rows set at an angle to each other on a single crankshaft?

  1. Radial engine
  2. Inline engine
  3. Opposed-piston engine
  4. V-type engine Correct answer.

Explanation

In a V engine the two cylinder banks share one crankshaft and are inclined to form a V. This shortens the engine compared with an inline arrangement of the same cylinder count. Inline engines have all cylinders in one row.

Question 49Automotive engine systems: construction, components and working principles

A four-cylinder four-stroke engine has a bore of 80 mm and a stroke of 90 mm. Using π/4 × bore² × stroke for one cylinder, what is the approximate total engine displacement?

  1. 2260 cm³
  2. 1810 cm³ Correct answer.
  3. 905 cm³
  4. 1440 cm³

Explanation

One cylinder volume is π/4 × 8² × 9 = 452.4 cm³. Multiplying by four cylinders gives about 1810 cm³. The other figures come from using the wrong number of cylinders or misplacing the bore and stroke values.

Question 50Automotive engine systems: construction, components and working principles

A petrol engine has a swept volume of 400 cm³ and a clearance volume of 50 cm³ per cylinder. What is its compression ratio?

  1. 8:1
  2. 9:1 Correct answer.
  3. 7:1
  4. 10:1

Explanation

Compression ratio equals (swept volume + clearance volume) divided by clearance volume, that is (400 + 50)/50 = 9:1. Using swept volume alone over clearance volume would incorrectly give 8:1. The clearance volume must be added to the swept volume first.