Odisha CHSE VOC-ITV Four Wheeler Service Technician key terms

Safety clothing and gear such as goggles, gloves, safety shoes and hearing protection worn in the workshop to reduce the risk of injury from sparks, chemicals, noise and heavy components.

A calibrated hand tool that tightens threaded fasteners to a preset turning force and signals, usually by a click, when that torque is reached, preventing over-tightening or loosening.

A precision measuring instrument with a calibrated screw spindle used to measure small outside diameters and thicknesses, commonly to 0.01 mm, for checking shaft, piston and disc wear.

A set of thin metal blades, each marked with its thickness, used to measure narrow gaps such as valve clearances, spark plug gaps and clutch free play.

The sequence of intake, compression, power and exhaust strokes completed by a piston in two crankshaft revolutions in a standard spark-ignition engine.

The ratio of the cylinder volume above the piston at bottom dead centre to the volume at top dead centre; it influences power, efficiency and fuel octane requirement.

The small gap between the valve stem tip and the rocker arm or cam follower, set to the manufacturer's specification so the valve can close fully when the engine is hot.

The exact position where the piston reaches its highest point in the cylinder and momentarily stops before moving down, used as the reference for ignition and valve timing.

A major repair in which the engine is removed, stripped, measured, worn parts are replaced or reconditioned, and the unit is reassembled, timed and tested before refitting.

A fuel delivery system in which an electronic control unit opens solenoid injectors for calculated periods to spray a precise amount of fuel into the intake or cylinder.

A diesel injection layout where a high-pressure pump feeds one shared accumulator rail connected to all injectors, so injection pressure and timing can be controlled independently.

An exhaust component containing a coated honeycomb that promotes chemical reactions converting carbon monoxide, hydrocarbons and nitrogen oxides into less harmful gases before they leave the tailpipe.

A sensor fitted in the exhaust stream that measures residual oxygen and sends a voltage signal to the engine control unit for correcting the air-fuel mixture.

A system that returns a measured portion of exhaust gas to the intake manifold, lowering peak combustion temperature and reducing the formation of nitrogen oxides.

A temperature-operated valve in the cooling circuit that stays closed during warm-up and opens at a set temperature to let coolant circulate through the radiator.

A mixture of water and glycol with corrosion inhibitors that transfers heat from the engine to the radiator, raising the boiling point and lowering the freezing point.

An engine-driven gear, rotor or vane pump that draws oil from the sump and delivers it under pressure to the crankshaft bearings, camshaft and other moving parts.

A friction coupling between the engine flywheel and gearbox that transmits drive when engaged and slips or separates when the pedal is pressed, allowing standing starts and gear changes.

A gearbox mechanism that uses cone clutches to bring the selected gear and its shaft to matching speed before the dog teeth engage, preventing gear clash.

A rotating tube, usually fitted with universal joints at each end, that carries torque from the gearbox or transfer case to the final drive.

A gear assembly between the driven wheels that divides engine torque while allowing the wheels to rotate at different speeds when the vehicle turns a corner.

Adjustment of camber, caster and toe angles so the wheels are positioned correctly relative to the vehicle and road, improving stability and reducing uneven tyre wear.

The tilt of a wheel from the vertical when viewed from the front, measured in degrees; too much negative or positive camber causes uneven tyre wear.

The forward or backward lean of the steering axis when viewed from the side, which provides self-centring force and straight-line stability at speed.

A hydraulic damper that converts suspension spring movement into heat, controlling bounce and keeping the tyres pressed against the road surface.

The height of the raised pattern above the grooves in a tyre, which clears water and maintains grip; it must remain above the legal minimum.

A braking arrangement in which pedal force is converted by a master cylinder into fluid pressure that operates wheel cylinders or calipers, pressing friction linings against rotating surfaces.

The procedure of opening bleed screws at each brake and expelling fluid until no air bubbles remain, restoring a firm pedal and reliable hydraulic pressure.

An electronic system that monitors wheel speed and rapidly modulates brake pressure at individual wheels to prevent locking, helping the driver keep steering control during hard braking.

A temporary loss of braking performance caused by overheating of friction material or brake fluid, often after repeated or prolonged heavy braking.

A rechargeable electrochemical device that stores energy and supplies direct current for cranking, lighting and ignition, and is recharged by the alternator when the engine runs.

A belt-driven generator that produces alternating current, rectifies it to direct current and regulates output to charge the battery and power electrical loads while the engine runs.

A test instrument that measures voltage, resistance and current, used to check continuity, sensors, wiring and charging-system output during electrical diagnosis.

An alphanumeric code stored by an electronic control unit when it detects an abnormal signal or condition, retrieved with a scan tool to guide fault diagnosis.

A diagnostic device that connects to the vehicle's data link connector to read trouble codes, display live sensor data and command actuator tests or resets.

A structured method that starts with the customer's description, verifies the complaint, then tests the most likely causes in order instead of replacing parts at random.

Scheduled servicing such as oil changes, filter renewal, inspections and adjustments carried out at set intervals to prevent breakdowns and maintain safe, efficient operation.

A checklist of checks and adjustments performed on a new or repaired vehicle before handover to confirm that it meets quality, safety and appearance standards.

A workshop document recording the customer complaint, authorised work, parts used and labour time, used to control the job, price the repair and support billing.

A unique seventeen-character code stamped on the vehicle that identifies its make, model, year, engine and specification, and is used for ordering correct parts.