Maharashtra SSC Automotive Service Technician Pre-Voc/NSQF key terms

Items worn by a technician to reduce injury risk, such as safety goggles, gloves, steel-toe shoes, ear plugs and coveralls. It is the last line of defence after guards, ventilation and safe procedures have been applied.

A standard document supplied with a hazardous chemical that lists its hazards, safe handling, storage, first-aid measures and spill response. Technicians must read it before using fuels, solvents, paints, adhesives or battery acid.

A procedure for isolating energy before maintenance: switching off, locking the isolator, attaching a warning tag and proving the machine cannot start. It prevents accidental start-up or release of stored energy during repair work.

The three conditions needed for fire: fuel, oxygen and heat. Removing any one extinguishes the fire, which explains why fuel spills must be cleaned and ignition sources kept away from the workshop.

A precision measuring instrument with a calibrated screw and spindle used to measure outside diameters, thickness and shaft sizes to 0.01 mm. The barrel and thimble scales are read together after the spindle contacts the work.

A measuring tool with jaws and a sliding vernier scale used for outside, inside and depth measurements, commonly to 0.02 mm. The main scale reading is added to the vernier coincidence reading.

A gauge with a spring-loaded plunger and needle that shows small linear displacements, used with magnetic bases for runout, end play, backlash and shaft alignment checks. Readings are compared against the manufacturer's limit.

A set of thin, marked steel blades used to measure small gaps such as valve clearance, spark plug gap, piston ring end gap and clutch free play. The blade that fits with slight drag gives the measurement.

A wrench that clicks or indicates when a preset tightening torque is reached, ensuring fasteners such as cylinder head bolts and wheel nuts are tightened to specification. Incorrect torque can cause leakage, distortion or fastener failure.

The specified order in which multiple fasteners, such as cylinder head or manifold bolts, are tightened, usually in stages from the centre outwards. Following it distributes clamping load evenly and prevents gasket leaks or warping.

The operating cycle of most vehicle engines: intake, compression, power and exhaust, each completed in one piston stroke, with two crankshaft revolutions per cycle. Valve timing controls when each stroke occurs.

The ratio of cylinder volume above 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, set cold or hot as specified. Too little clearance can hold valves open and burn them; too much causes noise and reduced lift.

A sealing component clamped between the cylinder block and head that retains combustion pressure, coolant and oil. It fails through overheating, incorrect torque or warped surfaces, causing leaks or white exhaust smoke.

The clearance between the ends of a piston ring when fitted in a cylinder bore, measured with a feeler gauge. Too small a gap causes ring breakage when hot; too large allows blow-by and oil consumption.

Combustion gases escaping past worn piston rings or cylinder walls into the crankcase, raising crankcase pressure and causing oil mist, oil consumption and contaminated engine oil. It is checked with a leak-down or blow-by test.

Abnormal, explosive burning of the air-fuel mixture after spark ignition, producing a metallic knocking sound and possible piston damage. Causes include low-octane fuel, over-advanced timing, hot spots and excessive compression.

The small movement of the clutch pedal before the release bearing contacts the pressure plate, allowing full clutch engagement. Excess play causes incomplete disengagement; too little play causes slipping and bearing wear.

The bearing that presses on the clutch diaphragm or fingers when the pedal is operated, disengaging the drive. It is a wear item and becomes noisy when its races or lubricant deteriorate.

A gear set that lets the driven wheels turn at different speeds while cornering, while still transmitting drive. It contains a crown wheel, pinion and side gears, and its backlash and preload must be set correctly.

The small clearance between meshing gear teeth, such as crown wheel and pinion or steering gears, measured with a dial indicator. Too little causes noise and seizure; too much causes impact noise and wear.

A braking system that transmits pedal force through brake fluid to wheel cylinders or calipers, using Pascal's principle. Air in the fluid or a leak reduces braking force, so bleeding and leak checks are essential.

A classification of brake fluid by boiling point and composition, such as DOT 3, DOT 4 and DOT 5.1 glycol fluids or DOT 5 silicone. Glycol fluids absorb moisture and must be replaced periodically.

Loss of braking efficiency when brakes overheat, caused by friction material outgassing or fluid boiling. Symptoms include a spongy or long pedal and reduced stopping force during repeated hard braking.

Adjustment of camber, caster, toe and steering axis inclination so wheels meet the road correctly. Incorrect alignment causes uneven tyre wear, pulling and poor steering return, and is measured on an alignment machine.

Adding or removing small weights on a wheel rim so the rotating mass is evenly distributed, preventing vibration at speed. It is done on a balancing machine after tyre fitting and is separate from alignment.

Raised bars moulded into tyre grooves at a specified depth, showing when the tyre is worn out and must be replaced. Legal minimum tread depth and sidewall markings also indicate load and speed ratings.

The amount of energy remaining in a battery, indicated by open-circuit voltage or a hydrometer reading on serviceable cells. A low state of charge reduces cranking performance and can cause electronic faults.

A check of charging voltage and current at specified engine speed and electrical load, usually about 13.5 to 14.5 volts. Low output indicates a faulty alternator, regulator, belt or wiring.

Measuring the voltage lost across a cable, connection or switch while current flows, to find high-resistance faults. A good connection shows very little drop; excessive drop causes dim lights or slow cranking.

A vehicle self-diagnostic system that monitors sensors, actuators and emission performance, stores fault codes and illuminates the malfunction indicator lamp. Technicians read live data and codes with a scan tool.

An alphanumeric code stored by a control unit when a monitored circuit or system fails. The code identifies the affected circuit, but further testing is needed to find the actual cause.

An exhaust component with a coated honeycomb that converts carbon monoxide, hydrocarbons and nitrogen oxides into less harmful gases. It requires correct air-fuel ratio and unleaded fuel to work and avoid contamination.

The diesel combustion method in which air is compressed to a high temperature and fuel is injected and ignites without a spark plug. It explains diesel's higher compression ratio and different service requirements.

Metal inert gas welding, where a continuously fed wire electrode melts into the joint under a shielding gas. It is widely used for vehicle body panels and light structural repairs, with care for electronic components.

A short temporary weld used to hold parts in alignment before final welding or to join thin body panels in spaced spots. It limits heat distortion compared with a continuous bead.

The uniform clearance between adjacent body panels such as doors, bonnet and fenders. Correct gaps are checked during fitting and adjustment and affect appearance, wind noise and water sealing.

Scheduled servicing such as oil and filter changes, fluid checks, belt inspection and brake inspection, performed before failure occurs. It reduces breakdowns, extends vehicle life and lowers total ownership cost.

The distance or time set by the manufacturer between scheduled maintenance tasks, often with normal and severe-use schedules. It determines when oils, filters, belts and inspection items are due.

Driving the vehicle after repair to confirm correct operation of engine, transmission, brakes, steering and accessories under real conditions. It verifies the repair and helps identify symptoms that are not present at standstill.

A workshop document recording the customer's complaint, vehicle details, work authorised, parts used, labour time and technician observations. It supports accurate billing, follow-up and warranty claims.

A written or verbal statement of the expected cost of a repair or service, including parts and labour, given before work begins. Customer approval of the estimate protects both parties from billing disputes.

Recommending additional genuine services or products that genuinely benefit the customer, such as a coolant change or brake pad replacement found during inspection. It must be based on evidence and customer consent, not pressure.

A housekeeping method using sort, set in order, shine, standardise and sustain to keep a workshop clean, safe and efficient. It reduces time wasted searching for tools and improves safety and quality.