MITO Light Auto L3 key terms

Clothing and equipment worn to reduce the risk of injury, such as safety glasses, gloves, hearing protection and steel-toed boots. It is the first line of defence against cuts, burns, chemical splashes and flying debris in a workshop.

A supplier document listing a chemical product's hazards, safe handling, storage, first-aid measures and spill procedures. Technicians read it before using solvents, brake fluid or coolant so that exposure, storage and disposal are managed safely.

A wrench that signals, by click, beep or dial, when a preset tightening force is reached, so fasteners are clamped to the manufacturer's specification. Over-tightening stretches bolts, while under-tightening allows joints to work loose.

A rigid, adjustable support placed under the vehicle's chassis after it has been raised, so the hydraulic jack is not the only thing holding the load. Never work beneath a car supported only by a jack.

An extraction system that captures exhaust fumes, solvent vapour or dust at the point where they are produced and carries them outdoors. It protects the lungs where general workshop ventilation alone is not enough.

Sorting workshop waste into separate streams such as used oil, coolant, solvents, scrap metal, batteries and general rubbish, so each can be recycled or disposed of legally. Mixing streams can turn the whole container into hazardous waste.

The sequence of intake, compression, power and exhaust strokes that a piston completes in a spark-ignition engine. Two crankshaft revolutions are needed for one full cycle, during which the camshaft turns once.

The ratio between the cylinder volume with the piston at bottom dead centre and the volume remaining at top dead centre. Raising it improves efficiency and power but demands higher-octane fuel to avoid detonation.

A shaft with lobes that open and close the intake and exhaust valves in step with the crankshaft. Belt, chain or gear drive keeps the two shafts synchronised, and incorrect timing can let valves hit pistons.

A toothed belt that drives the camshaft from the crankshaft at exactly half engine speed. It must be renewed at the specified interval, because a failure on most engines bends valves and stops the car.

A heavy disc bolted to the crankshaft that smooths the power pulses between firing strokes and carries the starter ring gear. Its machined face also provides the friction surface for the clutch disc.

The mass of air mixed with a given mass of fuel, written as a ratio. Petrol engines run near 14.7:1 at stoichiometric mixture, and the control unit varies the ratio for power, economy and emissions.

A friction assembly that connects and disconnects the engine from the gearbox, allowing smooth pulling away and gear changes. A pressure plate clamps the driven disc against the flywheel when the pedal is released.

A fluid coupling containing an impeller, turbine and stator that multiplies engine torque and drives an automatic gearbox. Because it slips, the car can be held stationary in gear without stalling.

A compact arrangement of sun, planet and ring gears that produces several forward ratios and reverse. Holding or driving different members gives the gear changes an automatic transmission needs.

A special oil that transmits hydraulic pressure, lubricates gears and bearings and carries heat away inside an automatic gearbox. Using the wrong specification or leaving the fluid degraded causes harsh shifts and clutch wear.

A gear set that divides drive between the two wheels while allowing them to rotate at different speeds in a corner. Without it, tyres would scrub and the driveline would wind up on dry surfaces.

A constant-velocity joint at each end of a driveshaft that transmits drive smoothly through steering and suspension movement. A split rubber boot lets dirt in and grease out, causing clicking and rapid wear.

A pump operated by the brake pedal that pressurises hydraulic fluid and sends it to the calipers or wheel cylinders. A worn seal shows as a pedal that slowly sinks when held under pressure.

A hygroscopic hydraulic fluid rated DOT 3, 4, 5.1 or 5, which transmits pedal force and must resist boiling at high temperature. Absorbed moisture lowers its boiling point and corrodes system components.

Removing trapped air from the hydraulic brake circuit by opening each bleed screw in turn while an assistant holds pedal pressure. Air can be compressed, so a spongy pedal usually means bleeding is incomplete.

The clamp that straddles the disc and pushes one or more pistons to press the pads against it. Sliding calipers must move freely on their guide pins or they drag and wear unevenly.

An electronic system that releases and reapplies brake pressure at any wheel about to lock, so the driver keeps steering control during hard braking. Wheel speed sensors and a hydraulic modulator perform the correction.

Loss of stopping power caused by heat in the brakes, either from the pads outgassing or from brake fluid boiling. It builds after repeated hard stops and fades away again as the system cools.

A suspension layout in which the shock absorber and coil spring form the upper locating link, working with a lower wishbone. It is compact and inexpensive, but wheel geometry changes as the suspension travels.

Adjusting camber, caster and toe so the wheels sit at the correct angles relative to the car and road. Wrong settings cause uneven tyre wear, pulling to one side and an off-centre steering wheel.

The adjustable link that connects the steering rack to the hub carrier and sets the toe angle. A bent rod or worn end causes uneven tyre wear and vague, wandering steering.

A steering gear in which a pinion on the steering column turns a toothed rack, converting rotation into side-to-side movement of the tie rods. It gives direct feel with few moving parts.

A system that uses an electric motor on the steering column or rack to reduce driver effort, controlled by torque and speed signals. It uses less energy than a constantly driven hydraulic pump.

A damper that turns suspension movement into heat so the springs settle quickly after a bump and the tyres stay in contact with the road. Oil leaks and a bouncy ride show it has lost effectiveness.

A sealed rolling element that lets the hub rotate with very little friction while carrying the vehicle's weight. A worn bearing hums or rumbles, changes noise when cornering and can upset ABS operation.

A 12-volt lead-acid store of electrical energy that cranks the engine and stabilises system voltage while the car runs. Its capacity drops sharply in cold weather and deep discharge shortens its life.

A belt-driven generator that produces alternating current, rectifies it to direct current and charges the battery with the engine running. Its regulator holds system voltage at roughly 13.5 to 14.5 volts.

An electric motor whose pinion engages the flywheel ring gear to crank the engine until it fires. Slow cranking points to a flat battery, high-resistance cables or a failing starter.

A test instrument that measures voltage, resistance and current, and often continuity as well. Correct range and probe placement matter, because measuring current in parallel with a load blows the meter fuse.

Measuring the voltage lost across a cable, connector or switch while current flows, which reveals high resistance without disconnecting anything. Roughly half a volt lost on a main circuit indicates a fault.

A twisted-pair serial network that lets control units exchange short digital messages. Modules share engine, brake and body data over two wires instead of running a separate cable for every signal.

A microprocessor that reads sensors, runs control strategies and drives actuators. Engine, transmission, braking and body functions each have their own unit, and they communicate over the CAN bus.