Karnataka II PUC Automobile - Vocational (KSEAB) flashcards
Karnataka II PUC Automobile - Vocational (KSEAB) · Build recall with a focused review session.
33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Four-stroke cycle
- The sequence of intake, compression, power and exhaust strokes completed in four piston movements, giving one power stroke per two crankshaft revolutions.
- Compression ratio
- The ratio of total cylinder volume when the piston is at bottom dead centre to the volume remaining at top dead centre.
- Mechanical efficiency
- Brake power divided by indicated power, expressed as a percentage; it shows how much indicated work reaches the flywheel after friction losses.
- Flash point
- The lowest temperature at which a liquid gives off enough vapour to form an ignitable mixture near its surface; petrol has a very low flash point.
- Piston ring function
- Compression rings seal combustion gases against blow-by, while oil control rings scrape surplus oil from the bore back to the sump.
- Valve clearance
- The small gap between the valve stem and rocker or tappet, measured with a feeler gauge when cold, allowing thermal expansion.
- Firing order
- The specified sequence in which cylinders receive their power strokes, chosen to balance crankshaft loads and smooth engine running.
- Turbocharger
- A turbine driven by exhaust gas that turns a compressor to force more air into the cylinders, increasing power for a given displacement.
- Octane number
- A measure of a petrol's resistance to knocking, compared with reference fuels; a higher number allows higher compression without detonation.
- Cetane number
- A measure of diesel fuel's ignition quality; a higher cetane number means a shorter ignition delay and easier cold starting.
- Stoichiometric ratio
- The chemically correct air-fuel mass ratio for complete combustion, about 14.7:1 for petrol and about 14.5:1 for diesel.
- Thermostat
- A temperature-operated valve in the cooling system that stays closed while the engine warms and opens to send coolant to the radiator.
- Clutch free play
- The pedal or linkage travel before the release bearing touches the pressure plate, needed so the clutch engages fully without slipping.
- Gear ratio
- The number of teeth on the driven gear divided by the number on the driving gear; it sets the speed and torque change through that pair.
- Differential
- A gear set that divides drive to the wheels while letting them rotate at different speeds, as required when the vehicle turns.
- Torque converter
- A fluid coupling with impeller, turbine and stator that transmits and multiplies engine torque in place of a clutch in automatic transmissions.
- Ackermann steering
- A linkage geometry that turns the inner front wheel more sharply than the outer one, so both wheels roll without sideways scrub.
- Shock absorber
- A hydraulic damper that converts spring oscillation into heat, controlling body movement and keeping the tyres in contact with the road.
- Brake fade
- Loss of braking force when heat from repeated or prolonged braking reduces friction between lining and drum or disc.
- Tyre aspect ratio
- The tyre sidewall height expressed as a percentage of its section width; a lower ratio means a shorter, stiffer sidewall.
- Ohm's law
- The relationship V = I × R, meaning voltage equals current multiplied by resistance in a circuit at constant temperature.
- Alternator
- A belt-driven generator producing alternating current that is rectified by diodes to charge the battery and supply the vehicle's electrical loads.
- Electronic control unit
- A computer that reads sensor signals, calculates the required output and drives actuators such as injectors and ignition coils.
- CAN bus
- A twisted-pair serial network that lets electronic modules share data, reducing the number of wires in the vehicle harness.
- Compression test
- A check of each cylinder's peak pressure with the starter turning the engine; low readings reveal valve, ring or head gasket leakage.
- Cylinder leakage test
- A test that feeds compressed air into a cylinder at top dead centre and measures the percentage lost, locating leaks by listening.
- Hygroscopic brake fluid
- Brake fluid absorbs moisture from the air over time, which lowers its boiling point and can cause a spongy pedal and corrosion.
- Vernier least count
- The smallest measurement a vernier instrument can read, found by dividing the smallest main scale division by the number of vernier divisions.
- Micrometer least count
- The smallest reading of a micrometer, equal to the screw pitch divided by the number of thimble divisions, commonly 0.01 mm.
- Torque wrench
- A wrench that slips or signals when a set torque is reached, used to tighten fasteners to the manufacturer's specified value.
- Three-way catalytic converter
- An exhaust device that oxidises carbon monoxide and hydrocarbons and reduces nitrogen oxides, working efficiently only near the stoichiometric air-fuel ratio.
- Exhaust gas recirculation
- A system that returns a small part of the exhaust gas to the intake, lowering peak combustion temperature and so reducing nitrogen oxide formation.
- Regenerative braking
- A system in hybrid and electric vehicles that uses the motor as a generator during deceleration, recovering kinetic energy into the battery.