Red Seal Automotive flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Torque formula
- Torque equals force multiplied by distance from the pivot; in metric units it is expressed in newton-metres, and one newton-metre equals 0.7376 pound-feet.
- Micrometer reading
- Read the barrel in millimetres, then add the thimble division multiplied by 0.01 mm; the spindle moves 0.50 mm per full barrel revolution.
- Metric thread pitch
- The distance in millimetres between adjacent thread crests; an M8×1.25 fastener has a nominal diameter of 8 mm and a pitch of 1.25 mm.
- SDS sections
- A Safety Data Sheet has 16 standardized sections covering identification, hazards, composition, first aid, fire-fighting, handling, exposure controls, properties, stability, toxicity, ecology, disposal, transport, and regulations.
- Four-stroke cycle
- Intake, compression, power, and exhaust strokes occur in sequence; the crankshaft rotates two full turns and the camshaft rotates once per complete cycle.
- Engine displacement formula
- Displacement equals pi divided by four, multiplied by bore squared, multiplied by stroke, multiplied by the number of cylinders.
- Compression ratio
- The ratio of cylinder volume at bottom dead centre to volume at top dead centre, equal to swept volume plus clearance volume divided by clearance volume.
- Cylinder leakage test
- Pressurized air is fed into a cylinder at top dead centre; leakage above about 20 percent, or bubbles in the coolant, indicates worn rings, bad valves, or a head gasket fault.
- Ohm's law
- Current in amperes equals voltage in volts divided by resistance in ohms; it is written V = I × R and applies to each circuit branch.
- Parallel resistance
- The reciprocal of total resistance equals the sum of the reciprocals of each branch; two equal resistors in parallel give half the value of one resistor.
- Battery state of charge
- A resting 12-volt lead-acid battery reads about 12.6 volts at 100 percent state of charge and about 12.0 volts at roughly 25 percent.
- CAN bus termination
- A healthy high-speed CAN network has two 120-ohm terminating resistors in parallel, so resistance measured between CAN high and CAN low is about 60 ohms.
- Voltage drop rule
- Under load, total circuit voltage drop should generally be 0.5 volt or less, with each connection or cable contributing no more than about 0.1 volt.
- Gear ratio
- Driven gear tooth count divided by driving gear tooth count; a numerically higher ratio multiplies torque and reduces output speed.
- Overall drive ratio
- Transmission gear ratio multiplied by final drive ratio; it determines total torque multiplication and engine speed relative to road speed.
- Open differential
- A gear set that allows left and right wheels to turn at different speeds; it delivers equal torque to both sides, so the wheel with less traction spins.
- Driveshaft phasing
- The universal-joint yokes at both ends of a shaft must align in the same plane, and operating angles at each end should be equal and opposite to limit vibration.
- Hydraulic pressure formula
- Pressure equals force divided by piston area; increasing master cylinder bore area lowers line pressure for a given pedal force.
- DOT 5 brake fluid
- A silicone-based fluid that is not compatible with glycol-based DOT 3 or DOT 4 fluid; mixing them can cause seal swelling and braking loss.
- Brake fade
- Loss of braking friction caused by overheating of pads, shoes, or fluid; fluid boil produces a spongy pedal, while pad fade raises pedal effort.
- ABS warning lamp
- A lit yellow ABS lamp means the antilock function is disabled, but conventional hydraulic brakes normally remain operational; the fault should be diagnosed.
- Camber angle
- The inward or outward tilt of a wheel viewed from the front; negative camber tilts the top of the wheel inward toward the vehicle centreline.
- Caster angle
- The forward or rearward tilt of the steering axis viewed from the side; positive caster tilts the top rearward and improves straight-line stability.
- Toe setting
- The difference in distance between the front and rear of a pair of tires; toe-in means the front edges are closer together than the rear edges.
- Thrust angle
- The angle between the rear axle centreline and the vehicle's geometric centreline; a nonzero thrust angle causes the vehicle to dog-track.
- Refrigeration cycle
- Compressor raises refrigerant pressure and temperature, condenser rejects heat, expansion device drops pressure, and evaporator absorbs heat from cabin air.
- Superheat
- The difference between the actual temperature of refrigerant leaving the evaporator and its saturation temperature at the same pressure; a TXV regulates superheat.
- Subcooling
- The difference between the saturation temperature in the condenser and the actual liquid temperature at the condenser outlet; it indicates how much liquid reserve exists.
- Orifice tube system
- A fixed-restriction metering system that uses an accumulator on the low side to store excess refrigerant and prevent liquid slugging of the compressor.
- Airbag pretensioner
- A pyrotechnic or mechanical device that tightens the seat belt during a collision; it fires with the airbag and must be replaced after deployment.
- Structural urethane
- Adhesive used to bond windshields; it transfers loads between glass and body and requires a specified cure time before the vehicle is driven.
- Galvanic corrosion
- Corrosion caused when two dissimilar metals contact in the presence of an electrolyte; the less noble metal becomes anodic and corrodes.