Glossary of automotive terms
This glossary of automotive terms is a list of definitions of terms and concepts related to automobiles, including their parts, operation, and manufacture, as well as automotive engineering, auto repair, and the automotive industry in general. For more specific terminology regarding the design and classification of various automobile styles, see Glossary of automotive design; for terms related to transportation by road, see Glossary of road transport terms; for competitive auto racing, see Glossary of motorsport terms.
A
- accelerator
- A throttle in the form of a foot-operated pedal, or sometimes a hand-operated lever or paddle, by which the flow of fuel to the engine (and thereby the engine speed) is controlled, with depression of the pedal causing the vehicle to accelerate.[1]
- admission stroke
- See induction stroke.
- air brake
- 1. A type of brake in which the force that actuates the brake mechanism is provided by compressed air acting on a diaphragm within a brake chamber or servo. Such systems are used primarily in commercial vehicles.
- 2. An aerodynamic spoiler designed to retard high-speed vehicles.[1]
- airless injection
- A type of fuel injection which relies on mechanical pressure only; the normal method of injection in a diesel engine.[1]
- all-wheel drive (AWD)
- alternative fuel vehicle
- alternator
- A small electrical generator that converts mechanical energy into electrical energy in the form of alternating current, typically by using the engine to drive the rotation of a magnet which induces a current in a stationary armature. This electrical energy is then stored in the battery.
- antifreeze
- Any chemical, commonly ethylene glycol, that is added to the cooling water of an engine in order to decrease its freezing point for winter operation, when ambient temperatures may be below the normal freezing point of water.[1]
- articulated vehicle
- Any vehicle consisting of two or more usually separable wheeled units, such as a towing vehicle (e.g. a tractor unit) combined with a towed vehicle (e.g. a trailer or semi-trailer) that is often unpowered and carrying a load. Articulation is primarily in the steering mode, though some degree of horizontal axis articulation is usually also necessary to enable the combined tractor-trailer to negotiate road surface irregularities.[1]
- automatic transmission
- automotive design
- automotive engineering
- axle
- A horizontal transverse shaft or beam with spindles on which road wheels are mounted. There are many different types of axles, typically distinguished by their placement relative to the vehicle's center of mass and their intended use. Vehicles are often classified by the number of axles they possess.[1]
B
- back-fire
- An explosion of unburned or partially burned fuel that occurs in an exhaust or inlet system, rather than in the combustion chamber as intended.[1]
- ball and socket
- A type of mechanical joint in which a spherical end (the ball) moves freely within a recessed cavity of the same shape (the socket), commonly used in suspension and steering linkages.[1] Body-in-Blue
- brake
- brake fluid
- breeches pipe
- See Y pipe.
- bumper
C
- caliper
- In a disc brake system, the mechanism that brings the brake pads to bear on disc by a clamping or pinching action.[1]
- camber angle
- The angle between the plane defined by the circumference of the wheels and the vertical axis of the body or chassis of a vehicle, as viewed from the front or rear of the vehicle. If the top of the wheel is tilted outward, away from the body, the wheel is said to have positive camber; if the top is tilted inward, towards the body, it is said to have negative camber. Angled wheels are sometimes an intentional part of a vehicle's design, but most ordinary road vehicles are intended to have minimal or neutral camber (i.e. the wheels are completely parallel to the body and perpendicular to the road surface).
- caster angle
- The angular displacement of the steering axis from the vertical axis of a steered wheel, as seen from the side of the vehicle.
- chassis
- The structural lower part of a vehicle to which the running gear and body are attached,[1] or more generally the main load-bearing framework which supports all of a vehicle's mechanical parts and other components and on which the body is mounted.[2] Compare rolling chassis.
- choke
- A valve that restricts the amount of air entering an engine on the induction stroke, thereby enriching the fuel-to-air ratio for ease of starting and running, especially when the engine is cold.[1]
- clearance volume
- The volume remaining in a cylinder above the piston when it reaches top dead center.[1] See also swept volume.
- clocking
- Illegally tampering with a vehicle's odometer reading.[1]
- clutch
- combustion chamber
- The part of an internal combustion engine in which combustion occurs; in particular the space within a cylinder bounded by the top of the piston when at top dead center and the cylinder head in a reciprocating engine. Since most of the fuel/air mixture's combustion takes place in this space, its volume, shape, and design greatly affect the power, fuel efficiency, and emissions of the engine.[2]
- compression ratio
- The ratio between the maximum and minimum combined volume of an internal combustion engine's cylinder and combustion chamber.
- continuously variable transmission (CVT)
- coolant
- crankshaft
- A linear shaft that translates reciprocating motion created by the pistons of an engine into rotational motion via a series of "crank throws" or "crankpins" – additional bearing surfaces which are slightly offset from that of the shaft and which are attached to the connecting rods of the pistons. The crankshaft is often attached to a flywheel and vibrational dampers to reduce the pulsation characteristic of four-stroke cycles and other undesirable movement.
- curb weight
- See kerb weight.
D
- differential
- A system of gears capable of dividing the input torque of one shaft between two output shafts where the two shafts are likely to rotate at different speeds, as in cornering. The differential is used as the final drive of vehicles with two or more driven wheels.[1]
- dispersant
- A motor oil additive which separates and holds solid or liquid contaminants in suspension, preventing their settling or clumping and thereby reducing sludge deposition in the engine.[1]
- displacement
- The total volume swept by all of the pistons in all of the cylinders of an internal combustion engine, excluding the volume of the combustion chambers. Engine displacement is commonly used as a measure of an engine's size, and by extension as an indicator of the power the engine is hypothetically capable of producing and the amount of fuel it can be expected to consume.
- displacement factor
- An index of vehicle performance usually expressed as the product of the engine displacement and axle ratio divided by the product of the drive wheel rolling ratio and the vehicle's gross weight.[1]
- dive
- The dipping of a vehicle's front end that occurs when the brakes are applied. Dive is caused by a load transfer from the rear to the front suspension, as the inertial force of forward motion passes through the vehicle's center of gravity, which is higher than the points where the braking forces are exerted on the ground.[2]
- drive axle
- The axle or axles used to transmit torque from the drivetrain, imparted via a differential, to one or more drive wheels; a driven axle.[1]
- drive shaft
- The shaft or shafts by which mechanical power and torque is transmitted from the rest of the drivetrain to a differential (and hence to a driven axle and driven wheels).[1]
- drive wheel
- The wheel or wheels used to transform torque from the powertrain into tractive force, and to transmit that force from the tires to the road, overcoming stationary forces and causing the vehicle to move forwards or backwards; i.e. the wheels that are driven, as opposed to merely rolling under the momentum imparted to them. Vehicles may have any combination of driven wheels; power applied to the two front wheels or two back wheels is two-wheel drive (2WD), and power applied to all four wheels is four-wheel drive (4WD). Which wheels are driven is variable in all-wheel drive (AWD).
- drivebox
- See gearbox and transmission.
- drivetrain
- All of the components of a motor vehicle that are involved in delivering power to the drive wheels, excluding the engine or motor that generates the power. The drivetrain typically includes the clutch (if present), transmission, drive shaft, differential, and one or more axles. Contrast powertrain.
- drop arm
- See steering arm.
- dry clutch
E
- electric vehicle
- engine block
- The structure, typically cast in one piece, which contains and houses the cylinders, pistons, and other components of an internal combustion engine. Modern engine blocks usually also have an integrated crankcase, as well as coolant passages and oil galleries.
- engine configuration
- exhaust system
- The assembly of parts that conveys the gaseous products of the engine's combustion reactions (collectively known as exhaust) out of the combustion chambers, away from the engine, and ultimately into the atmosphere. In the most basic design, exhaust gases flow from each of the cylinder heads into an exhaust manifold and then through one or more exhaust pipes, which expel their contents behind or to the side of the vehicle. In modern systems, the exhaust may also flow through a turbocharger, various emissions control devices (e.g. a catalytic converter), and/or a muffler and resonator (to reduce noise and vibration) before exiting through one or more tailpipes.
F
- fan belt
- The endless belt that transmits rotational motion from the engine to the cooling fan.
- fender
- 1. The fixed part of a vehicle body exterior that frames the wheel well, with the primary purpose of blocking sand, mud, rocks, liquids, and other road spray that is thrown into the air by the rotating tire; or any deflector plate or structure mounted at the front or rear of a vehicle near ground level.[1]
- 2. A fixed side-panel that partially shrouds a tire from view and similarly serves to deflect road spray.[1]
- fifth-wheel coupling
- firing order
- The numbered sequence in which the cylinders of a multi-cylinder internal combustion engine are ignited.[1]
- flat engine
- flathead engine
- footprint
- The shape of the contact interface of a loaded tire with the ground.[1] See also contact length.
- four-stroke engine
- four-wheel drive (4WD)
- frame
- front-wheel drive
G
- gas pedal
- See accelerator.
- gearbox
- gear stick
- grille
- A grid or grating covering an opening in the body of a vehicle and allowing air to pass through it, especially an ornamental one at the front end of a vehicle designed to ventilate the radiator and engine compartment.
H
- handbrake
- Any brake operated manually by a hand lever, but especially a parking brake.
- hood
- The hinged cover over the engine compartment of a motor vehicle. Hoods can be opened to allow access to the engine and most other power and accessory components for maintenance and repair.
- hybrid vehicle
I
- idle speed
- The rotational speed of an unloaded engine at the minimum throttle setting.[1]
- idling
- Running a vehicle's engine while the vehicle is not in motion, without any loads except the engine accessories, e.g. while waiting at a traffic light.
- inline engine
- An internal combustion engine layout in which all cylinders are aligned in one row without any offset, i.e. in a single plane of the crankshaft axis. Inline layouts tend to be simpler in design and easier to build than flat or V-shaped layouts, smaller in physical dimension, and more broadly compatible with various engine designs because they can be mounted in any direction.[1]
- internal combustion engine
J
- jacking bracket
- jump lead
- One of a pair of heavy-duty electrical leads by which a vehicle with a discharged battery may be connected to an external source of power, such as a charged battery in another vehicle, in order to recharge the dead battery, a process known as a jump start.[1]
- jump start
- A procedure of starting the engine of a vehicle with a discharged or depleted battery by using jump leads from a charged battery or other external power source.[1]
K
- kerb weight
- The total mass of an unladen vehicle including standard equipment and all consumables necessary for operation, including water, motor oil, transmission fluid, brake fluid, coolant, etc., and (sometimes) a full tank of fuel, but excluding passengers and cargo. The precise definition varies by location. Compare gross vehicle weight.[1]
- kickdown
- A system that enables a driver to select a lower gear than the one automatically engaged by an automatic transmission, e.g. when accelerating rapidly, usually by depressing the accelerator pedal fully.[1]
- kingpin
- 1. The vertical or inclined shaft about which a steered wheel assembly pivots.[1]
- 2. The main fastening member between a fifth-wheel and semi-trailer.[1]
- knock rating
- See octane rating.
- knocking
- knockout axle
- A type of detachable axle, usually on a low-loader, the removal of which allows further lowering of the loading bed.[1]
L
- leaf spring
- lifting axle
- locking differential
M
N
- 1. The hollow or dished center part of a road wheel on which the rim is mounted.[1]
- 2. The face of a road wheel that is bolted to the hub.[1]
O
- octane rating
- odometer
- overhead valve engine (OHV)
- overspeed governor
- A device that limits the rotational speed of an engine, usually by controlling the fuel supply.[1]
P
- parking brake
- A mechanism used to keep a vehicle securely motionless when parked, often consisting of a cable connected to two conventional wheel brakes (usually on the rear wheels), and also to a pulling mechanism, typically either a hand-operated lever or pull handle located near the steering column or a foot-operated pedal near the other pedals.
- piston
- platform
- A set of common design, engineering, and production efforts, as well as major automotive components, shared between a number of outwardly distinct vehicle models and even different vehicle classes which are often manufactured by different though usually related marques. Auto manufacturers commonly introduce new models based on existing platforms in order to reduce the costs associated with the development of entirely new products.
- play
- Free movement or looseness within a mechanical system, especially when not intended by the mechanism's design, e.g. any motion of a steering wheel before the steered wheels respond by turning.[1]
- powertrain
R
- rack and pinion
- A type of linear actuator comprising a circular gear (the pinion) engaging a linear gear (the rack), which operate together to translate rotational motion into linear motion or vice versa: rotating the pinion causes the rack to be driven linearly, and driving the rack linearly causes the pinion to rotate. Rack-and-pinion mechanisms have been employed in many different automotive systems and components, as in rack-and-pinion steering.
- rear-wheel drive
- redline
- 1. The maximum rotational speed, in revolutions per minute (rpm), at which an internal combustion engine or traction motor and its components are designed to operate without causing damage to the components themselves or to other parts of the engine assembly. The redline of a particular engine depends on various factors such as stroke, displacement, and the mass, composition, and balance of the engine components. The term is derived from the red-colored line or colored sector of a tachometer display which indicates the maximum allowable sustained engine speed.[2]
- 2. To operate a vehicle above its engine's redline. Straying above the redline usually does not mean instant engine failure, but may increase the chances of damaging the engine.
S
- sludge
- soak time
- solenoid switch
- solid injection
- See airless injection.
- spark ignition
- A system that uses a high-voltage electrical arc or "spark" to ignite a fuel/air mixture.[1]
- spark plug
- An insulated plug that supports the electrodes between which the electrical arc or "spark" passes to initiate ignition of a spark-ignition engine.[1]
- speedometer
- A gauge that measures and displays the instantaneous speed of a vehicle. Universal in modern automobiles and typically mounted on the dashboard behind the steering wheel.
- straight engine
- See inline engine.
- strangler
- See choke.
- stroke
- subframe
- suspension
T
U
- undercarriage
- The wheels, axles, and suspension system of a vehicle, particularly a commercial vehicle; more generally, all of the parts of an automobile accessible from the underside of the vehicle.[1]
- unsprung mass
V
W
- wheelbase
- The longitudinal distance between the front and rear wheel axes of a vehicle.[1]
- wheelfight
- A rotary disturbance occurring in the steering wheel that is produced by forces acting on the steered wheels.[1]
- wheel well
- See fender.
- windshield
- The front window of an automobile, providing visibility in the forward direction of travel while protecting the occupants from the elements. Modern windshields are usually made of laminated safety glass, consisting of two curved sheets of glass with a plastic layer laminated between them, which is bonded to the window frame.
- wiring harness
Y
- Y pipe
- A two-branch exhaust manifold connecting the exhausts of a V engine to form a single exhaust.[1]
See also
- Glossary of automotive design
- Glossary of mechanical engineering
- Glossary of motorsport terms
- Glossary of road transport terms
- List of auto parts
- Outline of automobiles
References
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao Goodsell, Don (1995). Dictionary of Automotive Engineering (2nd ed.). Warrendale, PA: Society of Automotive Engineers, Inc. ISBN 1-56091-683-4. OL 796394M.
- ^ a b c d "Glossary of Car Terms". caranddriver.com. 15 June 2009.