Haryana BSEH Senior Secondary NSQF Automotive key terms

Special clothing and gear such as safety goggles, gloves, boots and ear defenders worn to reduce the risk of injury while working on vehicles or handling chemicals.

Letter groupings of fires by fuel type, such as Class A solids, Class B flammable liquids and Class C electrical, used to select the correct extinguisher for a workshop emergency.

Deliberate movement of fresh air through a work area to remove exhaust gas, paint vapour, fuel fumes and dust so that breathing air stays safe.

A calibrated hand tool that clicks, beeps or shows a dial when a set turning force is reached, used to tighten fasteners to the manufacturer's specified value without over-stretching them.

A precision measuring instrument with a calibrated screw spindle, used to measure small thicknesses and diameters such as brake disc wear or piston skirt size to hundredths of a millimetre.

A set of thin steel blades of known thickness used to check small gaps, for example valve clearance, spark plug gap or brake pad clearance.

A measuring tool that reads the internal diameter of a cylinder or bearing housing, usually used with a micrometer to calculate taper and ovality.

The sequence of intake, compression, power and exhaust strokes that a piston makes in two crankshaft revolutions to convert fuel energy into useful work.

The ratio of the cylinder volume with the piston at bottom dead centre to the volume at top dead centre, which strongly affects power, efficiency and fuel octane requirement.

The small designed gap between the valve stem and the rocker arm or cam follower that allows for heat expansion and keeps the valve sealing fully when closed.

A cylinder head or suspension fastener tightened to a specified torque and then turned a further angle so it stretches into its elastic limit and must be replaced after removal.

An abrasive finishing process that cuts a fine cross-hatch pattern inside a rebored cylinder so the new piston rings can bed in and retain an oil film.

The clearance between the two ends of a ring when it sits squarely in its cylinder, checked with a feeler gauge to allow for heat expansion without ring breakage.

Abnormally rapid uncontrolled burning of the air-fuel charge that produces a sharp metallic knock and can damage pistons, often caused by low octane fuel or excessive advance.

A condition where engine speed rises without a matching rise in road speed because the friction disc cannot transmit full torque, usually from wear, oil contamination or weak pressure plate springs.

The small amount of pedal or lever travel before the release bearing touches the pressure plate fingers, needed so the clutch fully engages and does not drag.

A gear set that lets the two driven wheels turn at different speeds during a turn while still sharing engine torque, containing a crown wheel, pinion and planet gears.

The small intentional clearance between meshing gear teeth, such as crown wheel and pinion, that allows lubricant film and heat expansion without binding.

A joint in a front-wheel-drive shaft that transmits power smoothly through large steering angles without speed fluctuation, usually protected by a rubber boot.

The process of removing trapped air from the brake lines by forcing fluid through the system at each bleed nipple until a clear, bubble-free stream appears.

Loss of braking force after repeated or prolonged use when heat builds up in the linings or fluid, reducing friction or causing vapour lock.

A classification of brake fluid by boiling point and composition, such as DOT 3, DOT 4 and DOT 5.1, which must never be mixed with silicone-based DOT 5.

Camber, caster, toe and steering axis inclination settings that determine how the tyres meet the road and affect straight-line stability and uneven tyre wear.

Adding small weights to a wheel rim so its mass is evenly distributed about the axle, preventing vibration at speed and uneven tyre wear.

The release of hydrogen and oxygen from a lead-acid battery during charging, which requires ventilation and a ban on sparks or flames nearby.

A test instrument that measures voltage, current and resistance, used to trace open circuits, shorts and excessive voltage drop in vehicle wiring.

A live measurement of the potential difference across a cable, switch or connection while current flows, revealing unwanted resistance that a simple continuity check would miss.

A two-wire serial bus that lets electronic control units share sensor and status data, reducing wiring and allowing scan-tool fault codes to be read.

The vehicle's self-monitoring system that stores fault codes and freeze-frame data in the engine control unit, retrieved through a diagnostic link connector.

A piezoelectric device bolted to the engine block that detects detonation vibrations and signals the control unit to retard ignition timing.

A system that routes a small portion of exhaust gas back into the intake to lower combustion temperature and reduce nitrogen oxide emissions.

A honeycomb device in the exhaust stream coated with precious metals that converts carbon monoxide, hydrocarbons and nitrogen oxides into less harmful gases.

An oxygen sensor in the exhaust that reports the air-fuel ratio to the control unit so injection quantity can be trimmed toward stoichiometric mixture.

A trap in the exhaust of a diesel engine that collects soot particles and burns them off periodically during a regeneration cycle at high temperature.

A finish supplied as base and hardener that cures by chemical reaction, giving a hard durable coat but requiring respiratory protection and accurate mixing ratio.

A paint defect with a bumpy skin-like texture caused by incorrect spray viscosity, air pressure, gun distance or drying conditions.

A logical process of verifying the complaint, gathering information, testing from cause to effect and confirming the repair, rather than replacing parts by guesswork.

A structured check of a new or repaired vehicle covering fluids, fasteners, lights, tyre pressures, road test and documentation before handover to the customer.

A housekeeping discipline of sort, set in order, shine, standardise and sustain that keeps tools, parts and aisles clean, labelled and easy to find.

A written record of the customer complaint, vehicle details, work authorised, parts used, labour time and technician sign-off that supports billing and warranty claims.

A short written breakdown of each step of a workshop task, the hazards involved and the controls applied before work starts.