RBSE SS Voc Automotive flashcards
RBSE SS Voc Automotive · Build recall with a focused review session.
34 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Compression ratio
- The ratio of total cylinder volume with the piston at bottom dead centre to the volume at top dead centre. Petrol engines run lower ratios than diesel engines.
- Torque-to-yield bolt
- A fastener tightened to a specified torque and then rotated through a set angle. It stretches permanently and must be replaced after removal.
- Valve clearance
- The small gap between the valve stem and rocker or cam follower. It is measured with a feeler gauge and set to the manufacturer's cold or hot specification.
- Cylinder taper
- The difference in bore diameter between top and bottom of the cylinder. It is measured with a bore gauge and compared with the wear limit.
- Synchroniser ring
- A cone-shaped ring that uses friction to bring the gear and shaft to the same speed before engagement. Worn rings cause gear grinding.
- Clutch free play
- The small travel of the clutch pedal before the release bearing contacts the pressure plate. Too little causes slip; too much prevents full disengagement.
- Torque converter stall
- The maximum engine speed reached with the output shaft held stationary and full throttle applied. It indicates converter and engine matching.
- CVT
- Continuously variable transmission. It changes ratio steplessly using a belt or chain running between variable-diameter pulleys.
- Final drive ratio
- The number of ring gear teeth divided by pinion gear teeth. It converts gearbox output speed into wheel speed and affects acceleration and fuel economy.
- Universal joint phasing
- The alignment of the yokes at each end of a driveshaft so they lie in the same plane. Correct phasing cancels speed fluctuation and prevents vibration.
- Limited-slip differential
- A differential that limits speed difference between driven wheels using clutch packs or a viscous coupling, improving traction when one wheel loses grip.
- Thrust angle
- The angle between the geometric centreline of the rear axle and the vehicle centreline. A non-zero thrust angle causes the vehicle to pull or steer off-centre.
- Caster angle
- The tilt of the steering axis in side view. Positive caster improves straight-line stability and steering self-centring after a turn.
- Ackermann geometry
- Steering linkage design that gives the inner front wheel a larger steer angle than the outer wheel, so all wheels turn about a common centre.
- Toe setting
- The difference in distance between the front and rear of the front tyres. It is adjusted last during wheel alignment because it is most sensitive.
- Ohm's law
- The relationship V = I × R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms. It underpins all circuit testing.
- Voltage drop test
- A measurement of voltage lost across a cable or connection while current flows. More than about 0.5 V indicates excessive resistance.
- CAN bus
- A two-wire differential network used in vehicles. CAN-High and CAN-Low carry data with 120 ohm termination at each end of the bus.
- Cold cranking amps
- The current a battery can deliver for 30 seconds at −18 °C while maintaining at least 7.2 V. It indicates starting capability in cold weather.
- Fuel trim
- The ECU's correction to fuel delivery based on oxygen sensor feedback. Positive long-term trim indicates a lean condition; negative trim indicates rich.
- Cylinder leakage test
- A test that pressurises each cylinder and measures the percentage of air lost. Listening at intake, exhaust, or oil filler locates the leak.
- Freeze frame data
- Engine and sensor readings recorded by the ECU at the moment a fault code was set. It helps reproduce and confirm intermittent faults.
- Brake fluid hygroscopy
- Brake fluid absorbs moisture from the air over time. Moisture lowers boiling point and can cause brake fade, so fluid is replaced periodically.
- Tread wear indicator
- A raised bar inside the tyre grooves at the legal minimum depth, usually 1.6 mm. Tyres worn to this bar must be replaced.
- Torque wrench storage
- A torque wrench is stored at its lowest scale setting so the internal spring is not compressed over long periods, which preserves calibration accuracy.
- Plastigauge
- A thin plastic strip placed across a bearing journal. After tightening, its crushed width is compared to a scale to determine oil clearance.
- Vernier least count
- The smallest measurement a vernier calliper can read, commonly 0.02 mm. It equals the difference between one main scale and one vernier division.
- Galvanic corrosion
- Corrosion caused when two dissimilar metals contact in the presence of an electrolyte. The less noble metal becomes anodic and corrodes preferentially.
- Thermoset plastic
- A plastic that cures into a rigid, infusible network and cannot be remelted or reshaped. It is used where heat resistance is needed.
- Primer in refinishing
- A coating applied to bare or prepared panels to promote adhesion and corrosion protection before sealer, base coat, and clear coat are applied.
- Paint film thickness
- The measured thickness of the applied coating layers. Excessive thickness causes cracking and poor adhesion, so it is checked with a gauge.
- Lockout tagout
- A safety procedure that isolates energy sources and attaches a personal tag during equipment maintenance. Only the person who applied it removes it.
- Break-even point
- The sales volume at which total revenue equals total costs. It is calculated as fixed costs divided by contribution per unit.
- Vehicle identification number
- A 17-character code stamped on the vehicle that identifies manufacturer, model year, assembly plant, and serial number. It is used in all official records.