SKM Motor Vehicle Mechanic L2 key terms

Items worn by a technician, such as safety glasses, gloves, coveralls and steel-toe boots, to reduce the risk of injury from chemicals, sharp edges, hot surfaces and flying debris.

A standard document supplied with a hazardous substance that lists its hazards, safe handling, storage, first-aid measures and spill response, used to plan safe workshop practice.

A procedure for isolating energy sources such as battery power, compressed air or hydraulic pressure and fitting a lock and warning tag before work begins on a vehicle or machine.

Separating used oil, coolant, brake fluid, solvents and batteries into correctly labelled containers so each stream can be recycled or disposed of without contaminating the environment.

Collecting drained engine, transmission and hydraulic oil in dedicated sealed tanks, never mixing it with solvents or coolant, and passing it to an approved recycler.

A measuring tool with a fixed main scale and a sliding vernier scale, used to read outside, inside and depth dimensions typically to 0.02 mm accuracy.

A precision measuring instrument using a calibrated screw and thimble to measure small outside dimensions, commonly to 0.01 mm, for parts such as pistons, journals and shims.

A set of thin metal blades of known thickness used to check small gaps such as valve clearances, spark plug gaps and piston ring end gaps.

A wrench that clicks, beeps or displays a reading when a preset tightening torque is reached, used so fasteners are clamped to the manufacturer's specification without over-stressing threads.

A gauge with a spring-loaded plunger and needle dial that shows small linear movement, used to measure runout, endplay and backlash on shafts and gears.

The sequence of intake, compression, power and exhaust strokes that a piston completes in two crankshaft revolutions, forming the basis of most petrol and diesel engines.

The small gap between the cam lobe or rocker and the valve stem, allowing for thermal expansion; incorrect clearance causes noise, poor sealing or valve damage.

A diagnostic check that cranks the engine and records peak cylinder pressure with a gauge, revealing worn rings, leaking valves or a blown head gasket.

A test that supplies compressed air to a cylinder at top dead centre and measures the percentage lost, with escaping air at the intake, exhaust or dipstick locating the fault.

A fastener tightened into its elastic limit and often then turned through a specified angle, so it must be replaced rather than reused after loosening.

A sealing layer clamped between the cylinder head and block that contains combustion pressure and separates coolant and oil passages from each other.

An instrument combining voltmeter, ammeter and ohmmeter functions, used to check supply voltage, circuit continuity, resistance and current draw in vehicle electrical systems.

Measuring the potential difference across a cable, connector or ground while current flows; a high reading shows unwanted resistance in that part of the circuit.

The relationship stating that voltage equals current multiplied by resistance, allowing a technician to calculate expected values and interpret meter readings in a circuit.

Current drawn from the battery by modules and accessories after the vehicle has gone to sleep, which can flatten the battery if it exceeds specification.

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

The safe practice of disconnecting and proving dead the traction battery circuit on hybrid or electric vehicles before any work, using insulated tools and rated gloves.

A condition where engine speed rises without a matching increase in road speed because the clutch friction disc cannot transmit full torque, often from wear or oil contamination.

A gearbox in which the driver selects ratios through a shift mechanism and engages drive through a clutch, using synchromesh to match shaft speeds.

An automated gearbox with two clutches serving separate odd and even gear sets, allowing the next ratio to be preselected for fast shifts without interrupting torque.

A transmission that varies its ratio steplessly, usually through a steel belt running between two adjustable pulleys, keeping the engine in an efficient speed range.

The small intentional clearance between meshing gear teeth or other paired components, measured to confirm correct assembly and to avoid noise or seizure.

Adjustment of camber, caster and toe so the wheels sit at the angles specified by the manufacturer, preventing uneven tyre wear and poor straight-line stability.

A joint in a driveshaft that transmits drive through a range of angles at near-constant speed, commonly used at the outer end of front-wheel-drive halfshafts.

A system that monitors wheel speed sensors and modulates brake pressure to prevent wheel lock-up during hard braking, preserving steering control.

The temperature at which brake fluid vaporises; absorbed moisture lowers it, so fluid is tested or replaced at the interval specified to prevent a spongy, fading pedal.

A sensor or metal tab that warns the driver, by dash light or squeal, that friction material has worn to its minimum thickness and pads need replacement.

An alphanumeric code stored by a control module when a monitored circuit or system falls outside its expected range, giving a starting point for diagnosis.

A questioning technique that repeatedly asks why a fault occurred to move from the visible symptom towards its underlying root cause before repairs are planned.

The manufacturer's table of service operations and intervals, based on time or distance, that keeps a vehicle reliable and within warranty conditions.

The measured thickness of rubber above the tread wear indicator, checked with a gauge to confirm the tyre meets the legal minimum and disperses water safely.

A documented history of maintenance, repairs and parts fitted to a vehicle, used to prove scheduled servicing, support warranty claims and inform future inspections.

A workshop document recording the customer's complaint, authorised work, parts used, labour time and technician sign-off for a specific repair.

The customer's explicit agreement, usually recorded in writing or on a job card, to additional work and cost before a technician carries it out.