Welcome to Truck Test Digest's
Truck Talk Glossary
With more than 200 cross-referenced vehicle terms (and growing), our Truck Test Digest glossary is the most comprehensive and consumer-friendly source for truck terms on the Internet.
The saying, "knowledge is power" especially applies when dealing in the truck and SUV arena. So, we wrote this glossary to demystify your truckin' experience; you'll find it helpful when selecting a vehicle or dealing with salespeople, loan officers, mechanics, and insurance companies. Now you can be "talkin' trucks" like the pros.
Click on any letter below to begin.
- A-Pillar
- The roof supports on either side of a car's windshield. The letter A indicates that these are the first pillars from the front of the truck or SUV.
- Active Safety
Features
- Safety features that require some action by a vehicle's occupants, such as seat belts.
- Aerodynamic Drag
- Air resistance encountered as a truck moves down the road.
- Air Bag
- A safety device that deploys in a severe frontal crash. Air bags are located in the steering wheel hub and in the passenger side dash pad.
- Air Conditioning
Compressor
- A pump that circulates refrigerant chemical through the air conditioning system.
- Air Dam
- A spoiler located beneath the front bumper. Though it serves a cosmetic purpose, an air dam is usually shaped to reduce the airflow under the truck, lower aerodynamic drag and reduce lift. It can also be contoured to increase the airflow to the radiator.
- Air Filter
- A component that contains a cartridge made of special material, usually a form of paper, which will allow air to pass through but will trap small airborne particles. The air filter becomes saturated with dirt over time and needs periodic replacement.
- Air/Fuel Mixture
- Liquid fuel, gasoline or diesel, must be converted to a vapor before it can be ignited in a combustion chamber to release its kinetic energy. A gasoline engine runs most efficiently when the fuel/air ratio is around one part fuel to 14 parts air. This mixing and atomizing of fuel and air is done either in a carburetor, which is not found on modern vehicles, or by a fuel injection system.
- All Season Tire
- A tire that provides traction under all weather conditions.
- All Wheel Drive
- Another way of saying Four-Wheel Drive (4WD), although All-Wheel Drive (AWD) usually operates full time and does not require the driver to actively engage the system. The system automatically distributes power between the front and rear wheels as needed.
- Alternator
- A component of the electrical system, it converts 12-volt DC (Direct Current) from the battery into AC (Alternating Current) at the rate of 13.8 to 14.2 volts. The alternator also provided electric power to operate the engine and accessories.
- Anti-Lock-Braking
System (ABS)
- A braking system that uses electronic sensors to detect when any of the wheels have locked up, or are about to. When the brakes are applied with maximum force, such as in a panic stop, the ABS pumps the brakes up to 30 times a second. This action prevents the wheels from locking up and allows the driver to maintain steering control, although it does not stop the truck in a shorter distance.
- Anti-Roll Bar
- A suspension component that reduces body roll.
- Antifreeze
- A liquid that cools a truck's engine but will not freeze. Antifreeze was once used only in cold weather but today's trucks use antifreeze, more properly called coolant, year round. It should be checked regularly and changed at specified intervals.
- Automatic
Transmission
- A transmission where the gears are shifted automatically without any input from the driver. These transmissions have 3, 4 or 5 speeds. In 4 and 5 speed transmissions, the highest gear is for overdrive, which provides better gas mileage at cruising speeds.
- Axle
- A steel shaft that connects the differential to the drive wheels.
- Daytime Running Lamps (DRLs)
- Lights that automatically turn on when a vehicle is started, making it more visible during daylight hours.
- B-Pillar
- The roof support behind the front doors. It's the second support pillar from the front of the vehicle.
- Ball Joint
- A flexible ball and socket joint used primarily in front suspensions.
- Base Model
- The least expensive version of a vehicle model. Often these have few power accessories, the smallest engine, and a manual transmission.
- Beam Axle
- A rigid axle supporting the non-driven wheels.
- Beltline
- The line that separates a truck's greenhouse from its lower body.
- Block Heater
- 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.
- Body material
- What the body is made from. In most vehicles, this is a combination of welded steel stampings. Some vehicles are made of fiberglass or composite materials such as carbon fiber, though this type of construction is usually found only in exotic sports cars or racing cars.
- Body-On-Frame
Construction
- A method of vehicle construction in which the body, engine, driveline and suspension are bolted to a frame or chassis. Most light trucks are built this way but few passenger autos.
- Bore and Stroke
- Bore is the diameter of a cylinder and stroke is the maximum distance the piston travels within the cylinder. This is expressed in inches or millimeters (3.39 x 3.39 in, 86.0 x 86.0mm). The volume of a cylinder times the number of an engine's cylinders is its displacement.
- Brake Caliper
- A yoke shaped component of a disc-brake system. It contains the brake pads, a hydraulic cylinder and straddles the brake disc.
- Brake Fade
- A loss of the brake's ability to stop the truck. This occurs when the brakes heat up after heavy usage, as when driving down a long grade.
- Brake Pads
- The components of a disc-brake system that grip a disc and provide the force that brakes the vehicle. Hydraulic cylinders in the brake caliper actuate them.
- Brake Shoes
- The components of a drum-brake system that apply pressure to the brake drums and bring the vehicle to a stop. The surface of the shoes is a high-friction material that comes into contact with the inside of the drums as the shoes are pushed apart by a hydraulic cylinder.
- Brakes, Disc
- Brakes that use a disc connected to the wheel and a caliper, containing brake pads, that's attached to the wheel hub. When a driver applies the brakes, the pads are pushed against the disc by hydraulic force. The disc is pinched between a set of calipers and, as pressure is applied, slows the wheel and brings the truck to a stop.
- Brakes, Drum
- Brakes that use an iron casting shaped like a shallow drum that rotates with the wheel. Curved brake shoes inside the drum are pushed against the inside of the drum by hydraulic pressure to provide braking.
The third roof support on a vehicle. On a two-door or four-door, it's the pillar behind the rear-seat window. On a sport-utility or station wagon, it's the pillar behind the rear door. Additional pillars continue the alphabetic system; there may be a D-pillar and so forth.
- Camshaft
- A shaft with a cam, shaped like an eccentric circle, for each of an engine's intake and exhaust valves. As the camshaft rotates, each cam comes in contact with either a pushrod or rocker arm and converts rotary motion into linear motion that ultimately opens the valve (a spring closes it). One or more camshafts regulate the opening and closing of the valves in all piston engines.
- Camshaft,
Dual-Overhead (DOHC)
- See Camshaft, Overhead.
- Camshaft,
Overhead
- A valvetrain in which the engine's camshaft is in the cylinder head. This configuration locates the camshaft closer to the valves, as opposed to an in-block camshaft location, which allows the valvetrain components to be stiffer and lighter. In a single-overhead-cam (SOHC) layout, one camshaft actuates all of the valves in a cylinder head. In a double-overhead-camshaft (DOHC) layout, one camshaft actuates the intake valves, and the other operates the exhaust valves.
- Camshaft,
Single-Overhead (SOHC)
- See Camshaft, Overhead.
- Capitalized Cost
Reduction
- An up-front or down payment on a lease which can reduce monthly payments. The trade-in value of a vehicle may also be applied in place of, or in addition to, this payment.
- Carburetor
- The fuel system component that meters and mixes fuel and air in the proper proportion. The carburetor also atomizes this mixture and directs it to the intake manifold that distributes it through passages to each combustion chamber.
- Catalytic
Converter
- A component of the exhaust system — often simply called a "catalyst" — which chemically converts smog-producing emissions into less harmful compounds.
- Chains
- Accessories that can be fitted to a vehicle's driving wheels to improve traction in snow.
- Chassis
- The underlying structure of a vehicle. In vehicles with a frame, the chassis generally includes all of the mechanical components attached to the structure. In vehicles with unitized construction, the chassis includes all the components except for the body.
- Cladding
- Protective and decorative
panels along the lower body.
- Closed End Lease
- Also called a walk-away
lease, it gives the lessee the choice of returning the vehicle to
the dealer or buying it for the purchase option price when the lease
term is up.
- Clutch
- A disc-shaped mechanical
device that disengages the engine from the transmission.
- Clutch-Starter
Interlock
- A safety device
that prevents a truck from being started while it's in gear. The clutch
must be depressed for the engine to start.
- Coachwork
- Body building as applied
to an automobile. Usually used to describe custom body work. A
seldom used word, it is most often seen in reference to vintage or
classic vehicles.
- Coefficient of
Drag (Cd)
- The measure of the
aerodynamic efficiency, or drag, of a vehicle. An aerodynamically
efficient vehicle would have a drag coefficient, or "Cd,"
of about 0.30, although even lower, numerically stated, Cds are not
uncommon.
- Combustion
Chamber
- The space remaining
in the cylinder
when the piston is at the top of its travel. The combustion chamber
is mostly in the cylinder head and also contains the valves
and spark plug. The chamber is shaped to promote more efficient and
cleaner combustion.
- Compression
Ratio
- The ratio between
the volume of a cylinder
and combustion
chamber when the piston is at the
bottom of its stroke and when it's at the top. Within limits (see Detonation),
the higher the compression ratio, the more power is produced.
- Concept Truck
- A hand-built vehicle
designed by a manufacturer to test public reaction to a particular
design. Some concept vehicles, also called show trucks,
actually make it into production but most wind up in museums.
- Connecting Rod
- An I-beam shaped
metal rod that connects a piston to a throw on a crankshaft.
- Cooling System
Capacity
- The specified volume of
coolant required to fill the cooling system, expressed in liters or
quarts.
- Coupe
- A hardtop vehicle with
two side doors and less than 33 cubic feet of rear interior volume,
according to measurements based on SAE standard J1100. A two-door
automobile with more rear-seat room may be called a two-door sedan.
- Crankcase
- The portion of an
engine block that contains the crankshaft,
main bearings and oil sump.
- Crankshaft
- A heavy shaft with one or
more cranks, or "throws," that are attached by connecting
rods to the engine's pistons. As the piston moves up and down in the
cylinder, its linear motion is converted to rotary motion by the
crankshaft, which, in turn is connected through either a mechanical
(clutch) or hydraulic (torque converter) coupling to the
transmission.
- Crumple Zone
- Front and rear portions
of a vehicle's body that are designed to crush progressively to
better absorb the energy of a crash.
- Cylinder
- The tubular passage
through which a piston moves up and down. Automotive engines consist
of anywhere from four to 12 cylinders that are arranged in either a
straight line or in a V arrangement within the cylinder block.
- Cylinder
Head
- An aluminum or iron casting which contains the combustion chambers, the intake and exhaust ports, and much or all of the valvetrain.
- EGR
- Exhaust-gas recirculation
is an emission reducing technique that mixes some exhaust gases with
the incoming fuel.
- EPA Mileage
Ratings (MPG)
- The distance a vehicle
can travel per gallon of gasoline in specific conditions such as
city and highway driving as determined by the Environmental
Protection Agency. These are expressed as miles per gallon (MPG) and
are determined in tests conducted over a specific driving course
under laboratory conditions. The city fuel-economy test, also used
to test emissions compliance, is based on a drive through typical
Los Angeles urban traffic in the mid 1970s.
- EPA Passenger
Volume (cu. ft.)
- A vehicle's interior
volume as measured according to standards established by the
Environmental Protection Agency.
- Emissions
controls
- Components that
reduce exhaust emissions, including the catalytic
converter and EGR
system.
- Engine,
"Boxer" or Horizontally Opposed Cylinders
- An engine with its
banks of cylinders
arranged opposite each other in a flat configuration. It has a low
center of gravity and presents a lower aerodynamic profile.
- Engine, Diesel
- An engine that uses
diesel fuel rather than gasoline.
- Engine, Inline
- A type of engine
that has its cylinders
arranged in a straight line.
- Engine, V-Type
- An engine with its cylinders,
from two to as many as 12 in common practice, arranged in V-shaped
banks.
- Engine,
Water/Air-Cooled
- Water cooled engines
circulate liquid through the engine block and cylinder head, then
through a radiator, to dissipate heat caused by combustion and
friction. Air cooled engines use fins to dissipate the heat to the
atmosphere, although they are usually aided by a fan in automotive
applications.
- Engine-Control
System
- Modern engines use a
computerized system to regulate their operation. It uses sensors to
monitor and adjust the fuel/air mixture, combustion timing and other
functions to keep the engine operating at its maximum efficiency
according to pre-programmed schedules.
- Ergonomics
- The science of designing
objects to better accommodate human beings.
- Excess Mileage
- Any mileage above the standard annual allowance. At lease end, the lessee pays a predetermined charge for each excess mile. This does not apply if the lessee buys the vehicle.
- Facia
or Fascia
- The front of a vehicle -
grille, headlights, bumper and valance.
- Floorpan
- The largest stamped metal
part in a truck's body, it forms the floor and also provides the
attachment points for many of the truck's mechanical parts.
- Flywheel
- A metal disc bolted
to the end of the crankshaft.
The inertia of the spinning flywheel while the engine is running
smooths the engine's operation.
- Four-Wheel
Steering
- A rarely found steering
system in which the rear wheels as well as the fronts can be
steered.
- Four-Wheel-Drive
(4WD)
- A type of drive
system where power is fed to all four wheels through a system of
driveshafts, differentials
and axles. 4WD can be full-time or part-time with the driver
selecting whichever mode is preferred.
- Front-wheel-Drive
- A type of drive system
where power is fed to the front wheels.
- Fuel
Injection
- A system that delivers a spray of fuel to an engine in the proper amount. In modern engines, fuel injection is quite sophisticated and is controlled by the engine's computerized management system. There are several types of fuel injection including Throttle-Body, which sprays the fuel into a manifold for distribution to each cylinder, and Port Injection, which sprays the fuel directly into the intake port. Fuel injected trucks typically have an electric fuel pump, an inline fuel filter and a fuel pressure regulator in the system.
- Gap
Protection
- A form of insurance which
pays the difference between what is covered by conventional
insurance and what's owed on a lease if a leased truck is stolen or
wrecked.
- Global
Positioning Satellite (GPS)
- See Navigation System.
- Greenhouse
- The portion of a
truck's body above the beltline.
- Gross Vehicle
Weight Rating (GVWR)
- The combined weight of a
light truck and its load-carrying capacity.
- Ground Clearance
- The distance from the ground of the lowest point on a vehicle's undercarriage.
- Horsepower
The standard unit of measurement of an engine's power. One horsepower is the amount of energy needed to lift 550 pounds one foot in one second.- Hydraulic fluid
The fluid in a brake system that transfers the force of braking from the brake pedal to the calipers or brake shoes that ultimately slow wheel rotation. Though the fluid operates in a closed system, it requires regular checking and occasional replacement. - Hydraulic fluid
- Ignition
System
- The components of an
engine that cause a spark plug to arc and ignite the fuel/air charge
in the combustion chamber. These
components include, in addition to the spark plugs, a unit that
sends electricity to the spark plug at the correct interval.
Commonly known as a distributor, it is a fairly simple device in
older vehicles but is a sophisticated, computer controlled component
in more modern engines.
- Induction System
- The components of an
engine that provide its fuel. These may include, in older engines, a
carburetor and intake manifold. In more
modern engines a sophisticated, computer controlled fuel injection
system is the main component of an Induction System.
- Instrument Panel
(IP)
- The cluster of gauges
which display vehicle operating data.
- Intake
Port
- A passage in a cylinder
head leading from the intake manifold to the intake valve.
- Internal
combustion engine
- An engine in which a fuel/air charge is compressed within a combustion chamber and ignited to release its kinetic energy, which exerts force on a piston, which transfers the energy to a crankshaft and, ultimately, through the driveline, to the driving wheels. All automotive engines are of this type.
- Jack
- An apparatus for hoisting
a part of a truck from the ground to aid in repairs. Most jacks sold
with trucks are scissors or bumper jacks and are used for emergency
tire changes.
- Jumpstart
- Using a set of cables (called jumper cables) to start a truck or SUV with a dead battery by connecting them with a good battery. While most jumper cables connect one truck's battery to another, new systems with cables connected to 12-volt battery packs are becoming increasingly popular with drivers living in cold climates and remote areas.
- Keyless
Entry
- A remote-control system
that allows for locking and unlocking the doors and opening the
trunk. A keyless entry system may or may not be integrated with an alarm system.
- Knock Sensor
- A sensor that detects the point of detonation in the engine's cylinders. The knock sensor sends this information to the truck's computerized engine-control system, which makes adjustments to keep the engine operating near its detonation limit and running more efficiently.
- Lease
Term
- The number of months a
lease is in effect.
- Leasing
- A popular alternative to
the traditional ways of buying a vehicle - paying cash or financing.
The arguments for leasing: You can get a vehicle for very little money
up front. You pay less money every month. You get more vehicle for the
money, and you get to drive a new vehicle more often because,
presumably, you re-lease every two, three or four years. The
argument against it is that at the end of the lease, you own
nothing. Leasing is not recommended for people who tend to keep a
long time and people who drive a great deal. Buyers who are
uncertain about which path to take should compare the costs for each
option.
- Lessee
- The buyer who leases truck.
- Lessor
- The dealer or finance company that offers and administers the lease.
- Manifold,
Exhaust
- A component of the
exhaust system that combines the passage from each exhaust port into
one collector that directs exhaust gases to the catalyst, mufflers
and ultimately the tailpipe. The shape of the passages in an exhaust
manifold is carefully tuned for maximum efficiency.
- Manifold, Intake
- A component of the
induction system that distributes the fuel/air mixture from its
source, a carburetor
or fuel
injection system, through carefully
tuned passages to each cylinder.
- Manufacturer's
Suggested Retail Price (MSRP)
- The price of a vehicle,
and its options that is set by the manufacturer. Sometimes called
the sticker price, it is a guideline. The negotiated final price may
be higher or lower, depending on the demand for that particular
model. Some models can sell for more than the MSRP, while others can
sell for less.
- Master cylinder
- The component of a
braking system that forces hydraulic fluid under high pressure to
the brakes at each wheel. It has a reservoir that contains the
brake, or hydraulic fluid, and is part of a larger unit in power
brake systems.
- McPherson Strut
- A common suspension
component, the strut combines the springs and shocks into one unit.
- Mid-engine
Configuration
- A vehicle that has its engine
behind the passenger compartment but in front of the rear wheels.
Usually found in two-seater sports cars such as the Ferrari Dino and
Toyota MR2.
- Monocoque
- See "Unibody."
- Moroney Label
- The "sticker"
on a new vehicle— also called a Moroney label after the Senator who
wrote the legislation requiring it — is pasted on a window of the
vehicle. It shows the base price, all standard equipment, itemized
prices of manufacturer-installed options, transportation or freight
charges (also known as destination or delivery charges) and the
total manufacturer's suggested retail price (MSRP). The Monroney
label also includes details about the average fuel economy for the
vehicle, although this is sometimes found on a separate sticker, the
Environmental Protection Agency (EPA) Fuel Economy Label.
- Muffler
- A canister in the exhaust system that contains baffles and other material that silences a truck's exhaust.
- Navigation
System
- An increasingly popular
option which uses orbiting satellites to determine a vehicle's position
which can be shown on a map that's displayed on a dashboard video
monitor.
- Normal Wear and
Tear
- The amount of
deterioration that is permissible over the term of a lease.
- Normally
aspirated engine
- An engine without a supercharger
- Octane
- The measure of the
anti-knock (see Detonation) properties of gasoline. The higher the
octane number, the less likelihood of knocking.
- Odometer
- An instrument that
displays the accumulated miles that a vehicle has traveled. Trip
odometers can be reset to display the distance traveled on a
specific voyage.
- Off-lease
- Vehicles that have been
returned to a dealer after their lease term has expired.
- Oil
- The essential lubricant
for every engine. Oil is rated by viscosity, or thickness, which is
specified by the engine's manufacturer.
- Oil capacity
- The oil capacity of an
engine as specified by the manufacturer, expressed in liters or
quarts.
- Options
- New truck features
available at extra cost, including such things as anti-lock brakes,
power sunroof, power steering, power windows and door locks, air
conditioning and cruise control.
- Overall Height
- The distance from the
ground to the vehicle's highest point, expressed in inches or
millimeters.
- Overall Length
- A vehicle's maximum
exterior length, expressed in inches or millimeters.
- Overall Width
- A vehicle's maximum width, expressed in inches or millimeters.
- Parking
Brake
- A manually operated, as
opposed to hydraulic, brake system which locks the brakes of rear
wheels to keep the vehicle from rolling while it is parked.
- Passive Safety
Features
- Safety features that do
not require any action from a vehicle's occupants. These include air
bags, padded interior surfaces and vehicle bodies designed to absorb
the impact of a crash.
- Perimeter frame
- A type of vehicle
construction that used a tubular of box-section steel frame onto
which the body is bolted. Most often found in pickup trucks and
sport-utility vehicles.
- Platform
- The underlying
architecture of a vehicle, normally consisting of the floorpan
and other basic sheet metal panels. A platform can be shared among a
number of a given manufacturer's vehicles that outwardly look
different because they use unique body panels.
- Port, Exhaust
- Passages in the cylinder
head leading from the exhaust valves to the exhaust manifold.
- Port, Intake
- Passages in the cylinder
head leading from the intake manifold to the intake valves.
- Pound-Feet
- The unit of measurement
for torque (for example, 132 lb-ft @ 4800
rpm), which is a gauge of an engine's power. One pound-foot is equal
to the twisting force produced when a one-pound force is applied to
the end of a one-foot-long lever.
- Power steering
- Steering which is power
assisted to reduce the effort required to turn the steering wheel.
- Powertrain
- The engine and
transmission.
- Purchase Option
- A lease feature that
gives the lessee the opportunity to buy the vehicle at lease end for
its residual value.
- Purchase Option
Price
- The price at which the
lessee can buy the truck at the end of its lease.
- Pushrod
- In a valvetrain, pushrods are used to transfer reciprocating motion from the cam to the rocker arms.
- Quarter
Panel
- The body panel that
covers the area from the rear-door opening to the taillight area or
from the headlamp area to the front-door opening.
- Quartz Halogen
Headlamps
- A headlamp bulb having a quartz shell holding the tungsten filament and filled with an inert gas containing iodine or other halogen gases. This gas reduces the gradual evaporation of the tungsten filament and increases its life. These lamps emit more lighting power per watt than standard headlamps.
- RPM
- Revolutions per minute.
- Rack-And-Pinion
- A steering mechanism
which uses a circular gear that meshes with a toothed bar, called a
"rack." The ends of the rack are linked to the front
wheels. When the steering shaft rotates the gear, it moves the rack
from side to side.
- Radiator
- A component of the cooling system, the radiator transfers the heat of engine coolant circulating through it to the atmosphere.
- Rear-Wheel-Drive
- A type of drive system
where power is fed to the rear wheels via a driveshaft
and differential.
- Recirculating-Ball
- A steering mechanism
which uses a worm gear that meshes another gear that actuates the
steering arm. Ball bearings in a recirculating track reduce friction
between the two components.
- Redline
- The rpm limit of an
engine as indicated on a tachometer.
- Refundable
Security Deposit or Reconditioning Reserve
- Cash deposits made at the
beginning of a lease. These are spelled out in the lease contract
and are generally refundable if all lease obligations are met.
- Residual or
Lease-End Value
- The estimated market
value of a vehicle at the end of its lease. It may vary depending on
the lease term, mileage allowance and the vehicle's make and model.
- Roadster
- An open-top, two-seat
vehicle such as the Porsche Boxster of Corvette Convertible.
- Rocker Panel
- The lower portion of a
truck's body between the front and rear wheel openings.
- Rocker
arm
- A valvetrain component
that transfers motion from a pushrod, camshaft lobe, or the
valvestem.
- Rotary (Wankel)
Engine
- A variation of the internal combustion engine — perfected by Felix Wankel during the 1950s and 60s — which uses a triangle-shaped rotor instead of conventional cylinders and pistons.
- SAE
- Society of Automotive
Engineers. An independent group that sets many vehicle standards,
among other things.
- Seating Capacity
- The maximum number of
passengers a vehicle can accommodate with a seat belt for each
passenger.
- Sedan
- A hardtop vehicle with
four doors.
- Shock Absorbers
- Shock absorbers cushion
road vibration and bumps. They are connected to the wheel and the
truck's frame and are filled with oil, and sometimes air or nitrogen, to
soften the shock of rough roads.
- Side Impact Air
Bag
- A type of air bag
designed to protect occupants in side impacts. It may be located in
the seat back, door or along the door's upper perimeter.
- Side Impact
Intrusion Beam
- A steel structure within
a vehicle's doors designed to protect occupants from injury in a
side impact.
- Speedometer
- A gauge showing how fast
a vehicle is moving.
- Spoiler
- An aerodynamic device
attached to a truck's body, usually on the rear deck, in order to
reduce lift or aerodynamic drag thus improving traction and stability.
Front spoilers, though seldom seen on trucks, are
used to improve airflow and engine cooling.
- Standard
Equipment
- Features which are
included in the base price of a vehicle.
- Steering
Geometry
- Angles at which the
steering's components and related suspension parts are set. These
affect handling and include camber, caster, toe-in, and trail.
- Steering Ratio
- The ratio between the
gear that turns with the steering shaft and the gear which
translates that motion to the steering arm.
- Supercharger
- A compressor that pumps
air under pressure into an engine's induction system. When mixed
with fuel, the charge is denser than in an un-supercharged (or
normally aspirated) engine and produces more power during
combustion. The term is frequently applied only to mechanically
driven compressors, but it defines all compressors, including
turbochargers.
- Supercharger,
Positive Displacement
- A mechanically driven
compressor that puts out a specific volume of air with each
rotation.
- Supercharger,
Turbocharger
- A supercharger, or compressor, powered by an exhaust-driven turbine.
- Tachometer
- A gauge that displays the
revolutions per minute, or speed, of the engine.
- Targa
- A removable-roof body
style. The style was popularized by Porsche but has been used on
other, sporty brands of vehicles.
- Throttle
- The gas pedal.
- Torque
- The rotational equivalent
of force (see Pound-Feet).
- Torque Steer
- A tendency for a
front-wheel drive vehicle to turn in a particular direction when
power is applied.
- Towing capacity
- The heaviest weight a
vehicle can tow, as recommended by the manufacturer.
- Track,
Front/Rear
- The distance between the
centerlines of a vehicle's front/rear tires, expressed in
millimeters or inches.
- Traction Control
- An electronic control
system that prevents wheelspin. It uses sensors to detect when a
driven wheel is about to break traction and prevents it by either
reducing engine power and/or applying the brake.
- Transaxle
- A combination of transmission
and differential found in
front-wheel-drive vehicles. The differential is inside the
transaxle, and the drive axles are connected through constant
velocity joints (CV joints) to the wheels.
- Transfer Case
- A gearbox that
distributes power to the front and rear axles of a four-wheel-drive
vehicle. Depending on the vehicle, a transfer case may allow
shifting between two-wheel-drive, full-time four-wheel-drive,
part-time four-wheel-drive, and four-wheel-drive low range.
- Transmission
- A gearbox with a number
of selectable ratios which matches the engine's rpm and torque to so
that the vehicle is operating in the engine's most useful power
range while accelerating.
- Turbo
- See Supercharger,
Turbocharger.
- Turning Circle
Curb-to-Curb
- The tightest circle a
vehicle can negotiate as measured at the outer edge of the outside
tires.
- Turns
lock-to-lock
- The number of revolutions of a steering wheel between full left and right.
- Unibody
- A type of vehicle
construction that uses many stamped sheet components welded into a
single structure. In this manufacturing process the sheet metal body
parts are combined with stress-bearing structures so that the body
and chassis are a single unit. Also called "unit" or
"unibody" construction, it is the method used to build the
majority of small vehicles today.
- Universal Joint
- A joint that transmits rotary motion between two shafts that are not in a straight line.
- Valve
- The component that
regulates the flow of fuel and air into and out of a combustion
chamber. There are two kinds of valves, intake and exhaust. Most
engines only have one of each, but higher performance engines often
have multiple valves to increase their volumetric (the mass of
fuel/air which an engine can accommodate) efficiency.
- Valves, Multiple
Per Cylinder
- A valvetrain with three
or more valves in the combustion chamber.
- Valvetrain
- The components which
cause the valves to open and close, including the camshaft, tappets
(or, cam followers), pushrods, rocker arms, valve springs and
valves.
- Vehicle
Identification Number (VIN)
- A 17-digit combination of letters and numbers unique to each vehicle. It is located on the driver's side of the dashboard at the base where the windshield glass and dashboard meet.
- Weight
Distribution, Front/Rear
- The amount of a vehicle's
weight on the front and rear wheels. Expressed as a percentage and
in pounds.
- Wheel alignment
- Aligning a vehicle's
wheels, by checking and, if necessary, resetting front and/or rear
suspension and steering angles to the manufacturer's specifications.
Uneven tire wear or steering that pulls can indicate a need to have
the wheel alignment checked or adjusted.
- Wheelbase
- The distance between the centerlines of a vehicle's front and rear wheels, expressed in inches or millimeters.