MITO Light Auto L3 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Hierarchy of control

Ranked risk controls: eliminate the hazard, substitute it, apply engineering controls, then administrative controls, with personal protective equipment last because it protects only the wearer.

Safety data sheet

A supplier document listing a chemical's hazards, first-aid measures, handling, storage and spill procedures; it must be accessible to every worker who uses that product.

Wheel chock placement

Chock the wheels that stay on the ground, on both sides, before raising any vehicle; on a slope chock the downhill side first so the vehicle cannot roll.

Used oil disposal

Drain used engine oil into a sealed, labelled container and send it to a licensed recycler; never pour it into drains, soil or general waste because it contaminates groundwater.

Torque wrench conversion

To convert newton metres to pound-feet multiply by 0.738; to convert pound-feet to newton metres multiply by 1.356. Recalibrate a wrench after any drop or overload.

Four-stroke cycle

Intake, compression, power and exhaust strokes complete in two crankshaft revolutions, while the camshaft turns once and opens each valve once per cycle.

Compression ratio

The ratio of cylinder volume above the piston at bottom dead centre to the volume at top dead centre, calculated as swept volume plus clearance volume divided by clearance volume.

Stoichiometric air-fuel ratio

The chemically ideal mass ratio of air to fuel for complete combustion: about 14.7 to 1 for petrol and about 14.5 to 1 for diesel.

Torque-to-yield head bolt

A bolt tightened past its elastic limit using angle torque, so it stretches permanently and must be replaced each time the cylinder head is removed.

Interference engine

An engine whose valve and piston paths overlap, so a broken or jumped timing belt lets valves strike pistons, causing bent valves or cracked pistons.

Thermostat opening temperature

Typically opens between 82 and 90 degrees Celsius, then modulates coolant flow to hold engine temperature near optimum; a stuck-open thermostat causes slow warm-up.

Torque converter stall

The maximum engine speed reached with the turbine held stationary; torque multiplication is greatest at stall and falls to one-to-one as turbine speed approaches impeller speed.

Final drive ratio

Ring gear tooth count divided by pinion tooth count. A higher number gives more torque multiplication and acceleration but lower road speed at a given engine speed.

Open differential action

An open differential splits torque equally and lets wheels turn at different speeds; driveshaft speed equals the average of the two wheel speeds, so one spinning wheel loses drive.

CV joint boot failure

A split or torn constant-velocity boot lets grease escape and abrasive grit enter, producing clicking on turns or vibration before the joint fails completely.

Clutch slip test

Apply the parking brake, select a high gear and release the clutch slowly while accelerating; if engine speed rises without the vehicle moving, the clutch is slipping.

Hydraulic pressure formula

Pressure equals force divided by piston area. Fitting a larger caliper piston increases clamping force but requires more fluid volume and therefore more pedal travel.

Brake fluid hygroscopy

Glycol-based DOT 3 and DOT 4 fluids absorb moisture from the air, which lowers the wet boiling point and can cause vapour lock under heavy braking.

Brake disc minimum thickness

The wear limit stamped on the disc hub or casting; a disc ground or worn below it must be replaced because it can no longer dissipate heat safely.

ABS on loose gravel

Anti-lock braking prevents wheel lock, but on gravel or snow a locked wheel builds a wedge of material that shortens stopping distance, so ABS can lengthen it.

Brake bleeding sequence

Bleed the wheel furthest from the master cylinder first, then work closer, keeping the reservoir topped up; some ABS units also need a scan-tool bleed routine.

Camber angle

The inward or outward tilt of the wheel top from vertical when viewed from the front; excessive negative camber wears the inside edge of the tyre.

Caster angle

The fore or aft tilt of the steering axis from vertical. Positive caster improves straight-line stability and self-centring but increases steering effort.

Toe setting

The difference in distance between the front and rear of the two wheels. Incorrect toe produces feathered edge wear and rapid tyre scrub.

Damper function

A shock absorber controls spring oscillation by converting kinetic energy to heat; it does not carry vehicle weight, which is the spring's job.

Ackermann steering geometry

Front wheels are linked so the inner wheel steers a tighter angle than the outer, letting all wheels roll on circles sharing a common centre in a turn.

Ohm's law

Voltage equals current multiplied by resistance; power in watts equals voltage multiplied by current. These two relationships underpin every circuit diagnosis on the vehicle.

Series and parallel circuits

In series, resistances add and current is common; in parallel, voltage is common and total resistance is always lower than the smallest individual resistor.

Voltage drop testing

Measure voltage lost across a conductor while the circuit carries its normal load; more than about 0.5 volts total indicates excessive resistance at a connection or cable.

Parasitic drain limit

With all modules asleep, current draw should typically stay below about 50 milliamps; a higher reading flattens the battery over several days of standing.

CAN bus termination

The twisted-pair network is terminated at each end by a 120-ohm resistor, giving about 60 ohms measured across the bus; a different reading indicates a wiring fault.

NTC coolant sensor

A negative-temperature-coefficient thermistor whose resistance falls as coolant temperature rises; the control unit converts that resistance change into a temperature signal.