Glossary - Mechanical Terms
Click on an alphabet to see the terms and then click on the term to know its definition.
Provides better ride or handling. A variety of systems are used to vary shock-absorber firmness. Some automatically sense road conditions and adjust shock-absorber settings accordingly.
All products and services used in the repair and maintenance
Fuel pedal or throttle. A foot-operated pedal or hand-operated lever connected by linkage or electronics to control vehicle speed.
A system that injects air into the exhaust ports of an engine for combustion of unburned hydrocarbons in the exhaust gases.
An accessory which uses electric power to keep an engine that's been turned off from becoming too cold, which makes it hard to start in extremely cold climates.
Torque applied by a brake to a tire/wheel assembly, which slows or stops the vehicle.
A steering effect resulting from toe or camber changes as the suspension moves up and down.
The inward or outward angle which a front-wheel spindle makes with a vertical line, as viewed by either the front or the rear of the vehicle.
Induces chemical reactions that convert an engine's exhaust emissions into less harmful products prior to entering the environment.
The frame, suspension system, engine, and drive train of a vehicle. The assembled parts of the automobile without the body.
Also known as "knock," it is caused by the spontaneous combustion of the fuel/air mixture in a combustion chamber.
A measure of the aerodynamic sleekness of an object.
The power-transmitting components in a vehicle, including clutch, gearbox (or automatic transmission), driveshaft, universal joints, differential and axle shafts.
A device which absorbs and measures the power derived by an internal combustion engine.
Any solution that conducts an electrical current, such as a mixture of sulfuric acid and distilled water found in vehicle batteries.
An ignition system that uses transistors and other semiconductor devices as an electronic switch to turn the primary current on and off.
A non-load-carrying ball joint that maintains the position of the steering knuckle and provides the correct steering axis inclination angle; sometimes called pilot joint or friction joint.
A method of delivering fuel under pressure into an engine's combustion chamber. Fuel injection systems can be single-point, multi-point, etc. Replaces carbureted system.
A tread cutting process in which grooves of varying depths and angles are cut into a tire's tread to improve forward traction, braking, or lateral stability.
A failure of the liver to compensate for damage or injury; decrease or breakdown of liver function.
A situation where the center bore hole of a wheel is made to match up with the hub diameter of the vehicle; the wheel is then centered by the center hole, rather than the lug nuts.
Loss of traction at high speeds caused by a wedge of water, which lifts a tire off the road surface.
A device that receives metered fuel under relatively low pressure and is activated to inject the fuel into the engine under high pressure.
The tendency of any mass at rest to stay motionless, or any mass, which is moving to remain moving.
A device employing a ventury tube so that a high pressure stream flowing through the nozzle creates a lower pressure or a vacuum into which the gas to be compressed flows.
Is the derived unit of energy in the International System of Units.
An engine that is struggling to keep turning due to lack of revs. or the use of too high of a gear.
The ability of a vehicle to respond linearly to the driver's steering input at low cornering levels.
The Sensor that monitors the engines intake manifold pressure and transits the data to the engine controller.
A setting where the steering axis is inclined forward at the top as viewed from the side; a condition, which tends to cause instability.
Used to describe an aluminum specialty wheel that is cast in one piece; also the standard wheel found as OEM on production cars.
Reaction of a material with oxygen; usually resulting in degradation of the material.
Tires lose air normally through the process of permeation.
Pounds per Square Inch.
A thermocouple device used for measuring exhaust temperatures.
A Bulb with an inner quartz Bulb which holds a tungsten Filament.
A tire built with casing plies that cross the crown at an angle of 90 degrees.
The ability of a vehicle to return to a straight ahead attitude after removal of steering input.
The raised area circling the rim of the wheel and located slightly inward from the bead seat; to keep the tire from slipping into the rim well, if accidentally deflated.
A system of devices supporting the upper part (body and chassis) of a vehicle on its axles.
The product of a force applied through a lever arm to product a rotating or turning motion.
The difference in distance between each of the rear wheels and the centerline of the vehicle.
A specialty wheel comprised of a center section of aluminum or steel that is fastened to an aluminum or steel wheel.
A term describing the amount of radial and lateral force variation in a rotating part.
Side-to-side movement of a vehicle at low speeds, caused by a bent wheel or axle or by a tire with high lateral force variation.
A condition where the centerline of the wheel coincides with the mounting face.