Automotive Servicing NC I key terms

Gear worn to reduce injury risk, such as safety goggles, gloves, coveralls, and steel-toe boots. In a workshop it must be inspected before use and replaced when damaged or contaminated.

A step-by-step review of a task that identifies hazards at each stage and states the controls to apply before work starts. It is normally documented and discussed with the crew during a toolbox talk.

A procedure for isolating energy sources, applying a personal lock and tag, and verifying zero energy before servicing machinery or a vehicle system. It prevents accidental startup or release of stored energy such as pressure or springs.

A document supplied with a chemical that lists its hazards, safe handling, first-aid measures, and spill response. Workers consult it before opening fuels, solvents, coolants, or refrigerants.

Recording inspection findings, repairs done, parts used, and recommendations in clear, factual, and dated form. Good reports let the next technician or the customer understand the vehicle's condition without asking questions.

A written authorization listing the customer complaint, approved tasks, parts, labor, and promised completion time. Technicians record actual work and findings on it so billing and history stay accurate.

A wrench that releases or signals at a set torque so a fastener is tightened to specification without over-stretching. It must be zeroed after use and calibrated periodically for accurate readings.

The manufacturer-stated tightening value, usually in newton-meters or pound-feet, for a specific fastener and thread condition. Using the wrong value can strip threads, distort parts, or cause joint failure.

The prescribed order for tightening multiple fasteners, often in stages and a spiral or cross pattern. Following it distributes clamping load evenly and prevents warping of heads, covers, and wheels.

A precision instrument with a calibrated spindle and anvil used to measure outside dimensions to hundredths of a millimeter. The user must check zero and apply consistent thimble friction for repeatable readings.

A measuring tool with sliding jaws and a graduated scale for outside, inside, and depth measurements. The vernier scale lets the user read fractions of the main-scale division, commonly to 0.02 mm.

A set of thin metal blades of known thickness used to check gaps such as valve clearance, spark plug gap, or belt deflection. The correct blade should drag slightly when pulled through the gap.

A gauge with a spring-loaded plunger and needle that shows small linear movement on a graduated dial. It is used to check runout, end play, and backlash by comparing readings against a specification.

A manufacturer-defined plan of inspections, fluid changes, and part replacements at set time or distance intervals. Following it reduces breakdowns and keeps warranty coverage valid.

A structured list of items checked during a routine inspection, such as tires, lights, belts, fluids, and brakes. Each item is marked pass, fail, or adjusted, with notes on defects found.

The height of the rubber between a tire's grooves, measured in millimeters or thirty-seconds of an inch. Wear bars and legal minimums indicate when a tire no longer grips safely on wet roads.

Moving wheels to different positions at recommended intervals so wear is distributed evenly. The pattern depends on whether tires are directional, asymmetric, or mounted on staggered axles.

Verifying engine oil, coolant, brake fluid, transmission fluid, and washer fluid against marked levels with the vehicle on level ground and the engine in the specified state. Low or contaminated fluid signals a leak or service need.

The sequence of intake, compression, power, and exhaust strokes that completes one power event in a reciprocating engine. Valve timing and piston position define each stroke.

The small gap between the valve stem and the rocker or cam follower when the valve is closed. Too little clearance can hold a valve open; too much causes noise and lost lift.

A toothed belt that keeps the camshaft synchronized with the crankshaft. It must be replaced at the stated interval, and alignment marks must be observed to avoid valve and piston damage.

The radiator, pump, thermostat, hoses, and coolant that carry heat away from the engine. It maintains operating temperature and must be checked for leaks, pressure retention, and correct coolant mix.

The oil pump, filter, galleries, and oil that reduce friction and carry heat from engine parts. Correct grade and pressure protect bearings and moving surfaces from wear and seizure.

A check that applies a controlled current draw to a battery and observes whether voltage stays above a minimum. It shows whether the battery can crank the engine under real load.

A test instrument that measures voltage, resistance, and current, and often continuity. Selecting the correct function and range before probing a circuit prevents damage and false readings.

A drawing that shows circuit paths, wire colors, connectors, and component locations. Technicians use it to trace faults, identify shared grounds, and confirm which pins should have power or ground.

Measuring the loss of voltage across a conductor or connection while current flows. Excess drop reveals resistance from corrosion or loose terminals that a simple continuity check may miss.

The alternator, regulator, belt, and wiring that supply electrical power and recharge the battery while the engine runs. Testing confirms output voltage and current within specification.

Adjustment of camber, caster, and toe so wheels sit at the angles the manufacturer specifies. Incorrect alignment causes uneven tire wear and off-center steering.

Checking springs, shocks or struts, bushings, ball joints, and links for wear, leaks, and looseness. Findings explain ride complaints, noise, and irregular tire wear.

Removing air from the hydraulic brake system by opening bleed screws in the correct order while keeping the reservoir filled. Air causes a spongy pedal and reduced braking force.

Measuring friction material thickness and checking discs, calipers, and lines for wear or leaks. Pads worn to the limit or unevenly worn indicate replacement and further diagnosis.

A friction assembly that connects and disconnects engine power from the transmission during gear changes and standing starts. Wear or air in its hydraulic release circuit causes slip or poor engagement.

A gearbox in which the driver selects gears through a shifter and clutch. It uses synchros to match shaft speeds and requires the specified lubricant at the correct level.

A gear set that lets driven wheels turn at different speeds while cornering and multiplies torque to the axles. It needs the correct lubricant and backlash adjustment to run quietly.

A rotating tube with universal joints that carries torque from the transmission or transfer case to the axle. Vibration or clunking often points to worn joints, balance, or support bearings.