Haryana BSEH Secondary NSQF Automotive key terms

Special clothing and gear worn to reduce injury risk in the workshop, such as safety goggles, gloves, steel-toe boots, ear plugs and overalls. It is the last line of defence after guards and safe procedures.

The three elements needed for fire: fuel, oxygen and heat. Removing any one stops combustion, which is why fuel spills are cleaned and ignition sources kept away from flammable liquids and vapours.

Keeping floors, benches and aisles clean, dry and free of clutter, oil spills and loose tools. Good housekeeping prevents slips, trips and fires and makes tools easy to find and check.

A measuring tool with a main scale and a sliding vernier scale that reads outside, inside and depth dimensions, usually to 0.02 mm. The jaws must be closed and the scale zero-checked before use.

A precision instrument using a calibrated screw and thimble to measure small outside dimensions, commonly to 0.01 mm. The spindle and anvil are cleaned and the zero error checked with the anvils closed.

The smallest value an instrument can read, found by dividing the smallest main-scale division by the number of vernier or thimble divisions. It decides how precisely a measurement can be reported.

A set of thin steel blades of known thickness used to check small gaps, such as valve clearances or spark plug gaps. The blade that fits with slight drag gives the clearance.

A wrench that clicks or indicates when a set tightening torque is reached, so fasteners are neither loose nor over-stretched. Values are taken from the manufacturer's manual and applied to clean, lightly oiled threads.

The operating cycle of most vehicle engines: intake, compression, power and exhaust, each taking one piston stroke and two crankshaft revolutions. Valves open and close at set points in this cycle.

The ratio of cylinder volume with the piston at bottom dead centre to the volume at top dead centre. Higher ratios raise thermal efficiency but require higher-octane petrol to avoid knocking.

The small gap between the valve stem and rocker or cam follower when the valve is closed, allowing for heat expansion. Too little clearance causes burnt valves; too much causes noise and poor breathing.

A shaft with lobes that open the intake and exhaust valves in time with the crankshaft, driven by a belt, chain or gears. Its profile and timing set engine breathing and power delivery.

The casting bolted on top of the cylinder block that closes the cylinders and carries valves, ports, camshaft and spark plugs. It is tightened in a set sequence to a specified torque to avoid distortion.

A sealing layer between the cylinder head and block that holds compression, coolant and oil apart. Failure shows as white exhaust smoke, coolant loss, overheating or oil and coolant mixing.

A friction coupling that connects and disconnects the engine from the gearbox so the vehicle can start from rest and change gear smoothly. It slips during engagement and locks fully when the pedal is released.

The bearing that pushes the clutch diaphragm or pressure plate fingers when the pedal is pressed, freeing the friction disc. It is a wear item and often noisy when worn.

A stepped-ratio transmission in which gears on shafts mesh in selected pairs, giving several forward speeds and one reverse. Ratios trade engine speed against wheel torque and road speed.

A gear set that splits drive to the two wheels while allowing them to turn at different speeds in a corner. It also provides the final drive reduction between the propeller shaft and half shafts.

The number of teeth on the driven gear divided by the number on the driving gear. It tells how many input turns are needed per output turn and hence the torque and speed change.

A joint in a front-wheel-drive shaft that transmits power smoothly through large steering and suspension angles. A split rubber boot lets grit in and causes clicking on turns.

A system in which brake fluid transmits pedal force through pipes to wheel cylinders or calipers. Because liquid is nearly incompressible, force is multiplied by piston area differences.

Removing trapped air from brake hydraulic lines by opening each bleeder screw in turn while an assistant holds the pedal and fresh fluid is added. Air must never enter the master cylinder reservoir.

A hygroscopic hydraulic liquid, usually DOT 3 or DOT 4 glycol based, with a high boiling point. It absorbs moisture over time, lowering the boiling point and risking vapour lock under hard braking.

An electronic system that senses wheel lock and rapidly modulates brake pressure so the wheels keep turning during hard braking, preserving steering control on slippery surfaces.

Adjusting camber, caster and toe so the wheels point correctly relative to the vehicle and road. Wrong alignment causes uneven tyre wear and pulling to one side.

Adding small weights to a wheel rim so mass is distributed evenly about the axle, preventing vibration at speed. It is done on a balancing machine after tyre fitting.

A damper that converts spring oscillation into heat so the body settles quickly after a bump. A leaking or worn unit causes bouncing, poor grip and uneven tyre wear.

The height of the rubber blocks above the grooves, measured with a depth gauge. Legal minimums and wear indicators show when grip in wet conditions is no longer safe.

The charge a battery can deliver, usually stated in ampere-hours, plus a cold-cranking current rating for starting. Capacity falls in cold weather and as the battery ages.

A belt-driven generator that produces alternating current, rectifies it to direct current and charges the battery while the engine runs. Its regulator holds charging voltage near 14 volts.

A heavy-duty electric motor that cranks the engine through a pinion engaging the flywheel ring gear when the ignition switch is turned. It draws a very large current for a short time.

A test instrument that measures voltage, current and resistance, and often continuity. It is used to trace open circuits, check charging voltage and test sensors and fuses.

A sensor at each wheel that reports rotation speed to the ABS and engine control units. A dirty or damaged sensor disables ABS and may trigger a warning lamp.

A thin metal strip in a holder that melts and breaks the circuit when current exceeds its rating, protecting wiring and components. A blown fuse must be replaced with the same rating.

A number showing a petrol's resistance to knocking, measured against reference fuels. Higher ratings suit higher compression ratios; using a lower rating than specified can cause detonation.

The mass of air mixed with a unit mass of fuel, about 14.7 to 1 for petrol at stoichiometric conditions. The engine control unit varies it for power, economy and emissions.

An electrically operated nozzle that sprays a measured quantity of fuel into the intake port or cylinder. Clogged nozzles cause rough running, poor economy and emissions failure.

A heat exchanger that passes hot coolant through tubes and fins so airflow carries heat away. A blocked core or failed cap causes overheating and coolant loss.

A temperature-operated valve that stays closed while the engine warms and then opens to send coolant through the radiator. A stuck-open unit causes slow warm-up and poor heater output.

A toothed belt that drives the camshaft at exactly half crankshaft speed. It must be replaced at the stated interval; breakage on many engines causes valve and piston damage.

A manufacturer's list of checks and replacements at set time or distance intervals, such as oil, filters, belts and brake inspection. Following it prevents breakdowns and keeps warranty cover valid.

A measure of an oil's resistance to flow, graded by SAE numbers such as 10W-40. The first number reflects cold flow and the second the thickness at operating temperature.

A cartridge or spin-on element that traps metal particles and sludge before oil reaches bearings and galleries. It is replaced at every oil change to keep the bypass valve from opening.

The general workplace abilities employers expect alongside technical skill, such as punctuality, teamwork, safety awareness, problem solving and willingness to learn. They are assessed in NSQF vocational subjects.

Paying full attention to a speaker, not interrupting, and confirming understanding by summarising or asking questions. In a workshop it prevents mistakes when taking job instructions or customer complaints.

Starting and running a business, taking financial risk in return for profit. For a technician it can mean opening a repair workshop, estimating costs, pricing jobs and managing staff and customers.