| Ackerman
Steering |
Steering
geometry that allows a vehicle's outside wheel to turn fewer degrees
during a turn to compensate for the larger arch tracked by the outside
wheel. If a vehicle's outside wheel doesn't turn fewer degrees, the
wheels will begin to "buck" and "skid" while turning.
|
|
|
| Active
(ride) Suspension |
An
"intelligent" suspension system found on many luxury vehicles
that senses outside forces on a vehicle (roll, pitch, weight, etc.)
and generates it's own forces to counteract them. An active suspension
system uses a computer at it's heart to monitor conditions such as
vehicle speed, road conditions, ride height, etc., and activates a
hydraulic or air pump to increase or decrease pressures at each wheel's
suspension as required to achieve a more stable ride. |
|
|
| Adhesion
(tire) |
Ability
of a tire to maintain contact with the surface of the road without
losing traction. Also see Contact patch and Limit of adhesion. |
|
|
| Adjustable
shock (s) |
A
shock absorber that can be made stiffer or softer to increase ride
and handling characteristics. The adjustments can be made either electromechanically
(solenoid) or manually (turn knob/cable). In common applications,
the adjustments change orifice sizes inside the shock absorber which
regulate internal oil flow. Smaller orifice sizes restrict oil flow
more and produce a stiffer ride. |
|
|
| Advance
(timing) |
The
process of adjusting the timing so a spark plug fires earlier in
an engine's cycle. It is the opposite of Retarded timing. Older
engines used a small vacuum diaphragm attached to the engine's distributor
to move a plate inside the distributor (advance timing) according
to engine vacuum. Spark timing and advance are computer controlled
on modern engines.
|
|
|
| Aerodynamic(s) |
Air
resistance on a forward moving body -- such as your car or truck.
There are three components that affect aerodynamics: Drag, caused
by a vehicles' shape and protruding objects such as mirrors, Air friction
on the vehicle's surface, and airflow through the car or truck (for
ventilation purposes). An average-size car traveling at 55 miles (85
kilometers) per hour uses about 60 percent of its fuel and power to
overcome wind resistance. Vehicles with improved aerodynamic design
(less air resistance) get better fuel economy. Also see Air dam and
Wind tunnel. |
|
|
| Aftermarket |
Parts
and/or accessories which come from a source other than the auto manufacturer.
Numerous companies, large and small, produce a wide range of parts,
add-ons and accessories for vehicles such as air spoiler kits, suspension
kits, engine performance upgrades, replacement windshields, tires,
shocks, upholstery, bumpers, etc.. Companies which rebuild engine
components such as starters and alternators and sell through automotive
parts stores are also considered aftermarket suppliers, even though
they may be selling rebuilt parts made by the manufacturer. Aftermarket
parts are often less expensive than original parts and their fit and
quality can vary widely. Auto restorers appreciate the availability
of aftermarket parts for classic cars where original parts may have
been out of production for many years. |
|
|
| Airbag |
Part
of a passive restraining system used on passenger cars and trucks
beginning in 1987. An airbag consists of a deflated balloon which
is packed inside a module. The modules can be placed in the steering
column and in the dash on the passengers' side. In the event of
a collision the airbag rapidly inflates to help reduce injury to
occupants. Deceleration sensors on the vehicle are used to sense
an impact and trigger inflation. An airbag can inflate in just milliseconds.
Inflation is caused typically by the burning of a dry chemical that
turns into a gas. Holes or vents in an airbag allow it to deflate
quickly after a collision. Modern vehicles also use airbag technology
to prevent side impact injuries as well.
|
|
|
| Air
bag |
A
heavy duty rubber bladder used on some luxury vehicles (Lincoln Continentals)
as a suspension component. The air bags are fitted around struts.
Air pressure inside the air bags can be increased or decreased as
needed to vary ride/handling quality and compensate for cargo weight.
Also see Air springs. |
|
|
| Air
box |
A
device mounted inside the engine compartment of modern vehicles (usually
fuel injected) that houses the air filter. Outside air is drawn into
the air box and must pass through the air filter element on it's way
to the engine. The "squarish" plastic air box replaces the
traditional round metal air cleaner that was mounted above carburetors
on older engines. Also known as an air cleaner assembly. |
|
|
| Air
cleaner |
A
"squarish" plastic box or metal canister in the engine compartment,
which houses the air filter element and connects to the motor usually
by a heavy rubber tube. All air going to the engine must pass through
the air filter which removes dust and microscopic impurities. Older
vehicles with carburetors typically housed the air filter in a round
metal canister that was mounted directly above the carburetor. |
|
|
| Air-cooled
engine |
An
engine cooled by air rather than by a liquid coolant. Most vehicle
engines are liquid-cooled. In a traditional liquid-cooled engine,
coolant (water + antifreeze) is used as a medium to transfer heat
from the motor to the radiator where it is then transferred to the
air. An air-cooled motor uses thin fins directly on the cylinders
and other areas where heat builds up. Air rushing past the fins draws
the heat away into the atmosphere. Because there is no cooling system
to fail, air-cooled engines can be very reliable. Vintage Volkswagen
Beetle engines are a popular example of a durable air-cooled engine.
|
|
|
| Air
dam |
An
aerodynamic device used on either the lower front or rear of a vehicle
to direct airflow around the car rather than beneath it. Air dams
are typically made out of fiberglass or heavy rubber. They hang low
to the ground. At high speeds, air rushing under a vehicle moves faster
than air rushing over the car and tends to produce an 'airplane-wing
affect' generating lift. Racers increase traction by preventing air
from flowing beneath the car and using other aerodynamic tricks. When
used on the sides or rear of a vehicle air dams are often referred
to as a skirt. |
|
|
| Air
filter |
A
replaceable device mounted inside an air cleaner or air box assembly
which removes microscopic airborne dust particles from air going into
an engine. Microscopic dust particles can quickly cause engine damage
if not filtered out. Most air filters are made of a specially pleated
paper that contains a matrix of fibers which filter out of a specified
size but let air and particles too small to cause damage to pass through.
Air filters should be inspected and replaced periodically (about every
other oil change) as part of regular maintenance. |
|
|
| Airflow
sensor |
A
sensor used in an engine's fuel injection system. It measures the
amount of airflow through the intake manifold. A signal from the airflow
sensor is sent to the vehicle's computer to determine the amount of
fuel necessary. Also see Fuel injection. |
|
|
| Air
foil |
A
device (typically a wing) used on vehicles to deflect airflow and
improve traction. Basically an upside-down wing that creates a downward
force. Additional traction and improved cornering can be achieved.
|
|
|
| Air-fuel
mixture |
A
blend of air and fuel supplied to an engine which is used for combustion.
As an engine draws in air, a fine spray of fuel is sprayed from the
carburetor or fuel injectors into the passing airstream. The air/fuel
mixture is then drawn into the combustion chambers (cylinders) where
it is ignited by a spark plug. |
|
|
| Air-fuel
ratio |
The
ratio of the mass of air to the mass of fuel supplied to an engine.
From a chemical standpoint, a specific amount of air is necessary
to completely burn all carbon and hydrogen in a given amount of fuel
and produce carbon dioxide and water with no excess oxygen remaining.
Also see Stoichoimetric ratio. |
|
|
| Air
injection system |
An
emission control system where fresh air is injected into an engine's
exhaust ports (exhaust manifolds) to allow unburned hydrocarbons to
complete combustion. It also aids in converting carbon monoxide to
carbon dioxide. Also see Emission controls. |
|
|
| Airing
down |
An
off-road driving technique of lowering air tire pressures to increase
traction in sand and mud, and reduce the possibility of tire puncture
from sharp rocks. The secret to driving over sand and deep mud without
getting stuck is riding on top. During off-road driving, airing
down prevents damage from sharp rocks by letting the tire better
conform to the rock's shape. Letting air out of a tire also flattens
out the bottom of the tire and increases the tire's footprint by
two to three times providing additional traction. In addition, it
reduces a tire's loaded radius, essentially making the tire 'smaller',
which increases power to the wheels. The opposite of airing down
is airing up.
In
severe cases, off-roaders and park rangers my lower tires pressures
down to three or four pounds in order to crawl over sand! But running
trails with tire pressures at ten pounds is common. Also see: Four-wheel-drive,
Rock crawling and Loaded radius, Free radius and Onboard air compressor.
|
|
|
| Air
lock |
A
pocket of air that prevents the flow of fluid. Air pockets sometimes
occur in fuel, brake and hydraulic clutch lines. An air lock can also
occur in the cooling system. Air locks can be bled out. Some engines
have an air bleeder screw at the top of their head or intake which
must be opened when filling with coolant to allow air to bleed out
in order to avoid engine damage. |
|
|
| Air-mass
sensor |
See
Airflow sensor (above) |
|
|
| Air
pocket |
See
Air Lock (above) |
|
|
| Air
pump |
Part
of an air injection emission system. An air pump forces fresh air
through metal tubes connected to an engine's exhaust manifolds. The
fresh air helps unburned hydrocarbons to fully combust. Also see Emission
controls. |
|
|
| Air
ride |
See:
Air suspension and Air springs |
|
|
| Air
resistance |
See:
Aerodynamic drag (above) |
|
|
| Air
scoop |
An
opening in a vehicle's body panel that allows air to flow through.
The flowing air can be used to cool brakes, engine, radiator, etc.
Air scoops on a vehicle's hood can be used to force air into the engine's
intake system to aid in combustion. |
|
|
| Air
springs |
A
durable rubber bladder that when filled with air can be used in
place of a metal spring in a suspension system. Many luxury cars,
such as the 1988-1995 Lincoln Continentals used an air-ride suspension
which featured an air bladder mounted to a shock strut. Some advantages
of an air spring include it's variability; by increasing air pressure
to the bladder the ride height can be increased to compensate for
increased weight; reduced road noise and vibration transmitted to
the chassis and ride quality can be altered on-the-fly. Requires
an onboard air compressor.
Also
installed on pickup and heavy-duty trucks as an overload spring.
Some companies also sell large air bladders which can be used as
a jack to lift the side of a vehicle to change a tire.
|
|
|
| Air
suspension |
A
suspension system that uses heavy-duty rubber air bags at each wheel
instead of springs to suspend a vehicle and absorb bumps. Air suspensions
are frequently used on luxury vehicles because they can provide a
very comfortable and vibration-free ride. Another benefit of an air
suspension is it's variability. Air pressure can be increased or decreased
through the use of an onboard air compressor to stiffen or soften
the ride, or to adjust for additional weight. Also see Air spring
(above). |
|
|
| Alignment |
Usually
refers to wheel alignment. A vehicle's wheels and suspension must
be properly aligned for proper steering and handling. Major alignment
adjustments include checking and adjusting the caster, camber, toe,
and ride height. |
|
|
| Alloy |
A
metal composed of multiple elements. The combining of deferent elements
to metals can produce a metal with different properties such as greater
strength or specific expansion capacity. Steel can be combined with
carbon, nickel, manganese, chromium and other metals to produce a
much stronger material. Stainless steel is an alloy which contains
nickel that is very strong, heat and rust resistant and can be polished
into a mirror-like finish. |
|
|
| Allow
wheel(s) |
A
term used to describe any lightweight non-steel wheel. Lightweight
wheels are typically made from aluminum and magnesium alloys. The
term "mag" wheel originates from Magnesium wheels (very
lightweight but also rather expensive). The term "mag"
is often applied to aluminum and chrome wheels as well.
Alloy
wheels can be produced by casting (pouring molted metal into molds),
forging (hammering, stamping or pressing heated metal into the desired
shape) or from billet (creating a wheel by machining a solid piece
of metal - usually aluminum).
|
|
|
| All-wheel
drive |
A
drive system where power is directed to all four wheels. With more
drive wheels contacting the surface, traction and driveability are
greatly increased, particularly in low-traction conditions such
as mud, snow or ice.
All-wheel-drive
is similar in principal to four-wheel drive with the distinction
that most four-wheel-drive systems can be switched between two and
four-wheel- drive, while all-wheel-drive systems are typically full-time
systems.
|
|
|
| All-wheel
steering (AWS) |
A
steering system where both front and rear wheels pivot during steering.
The advantage of AWS is a significantly tighter steering radius compared
to two-wheel steering used on most vehicles. Particularly beneficial
for long wheelbase vehicles. |
|
|
| Alphanumeric
rating system |
A
measuring system used for tires begun in 1968 which is based on the
weight carrying capacity of a tire. Also see P-metric, Tire rating
system and Uniform tire quality grading system. |
|
|
| Alternator |
A
component mounted to a vehicle's engine that generates electricity
to charge up a vehicle's battery and run accessories such as lights,
power windows, etc. An alternator is driven by a belt connected to
the engine. It creates AC (alternating) current which is then converted
into DC current. Alternators are more efficient than DC generators
which were used until the mid 1960's. The also produce more current
-- necessary to power the increased number of accessories found on
modern vehicles. |
|
|
| Ammeter |
An
instrument which measures the amount of amperes of current flowing
through an electrical circuit. Also known as an amp gauge. |
|
|
| Ampere |
A
unit of electric current. The amount of amperes is equal to the
voltage divided by the resistance (in ohms) of an electrical circuit.
|
|
|
| Amplified
speakers |
Speakers
which use a dedicated amplifier separate from the radio or music source.
Usually positioned near the speaker or inside the speaker enclosure.
Commonly used with subwoofers and other speakers which require more
power than can be supplied by the vehicle's radio. Also used to power,
or 'drive' more speakers than a radio is designed to power . |
| |
|
| Anchor
point |
A
sturdy hook or bracket on an automobile or truck chassis where a tow
rope or cable can be attached for purposes of towing or extracting
from a ditch. |
|
|
| Angle
of approach |
See
Approach angle. |
|
|
| Anodize |
A
process using electrolytic action to coat or plate metal usually aluminum
to improve appearance and reduce corrosion. Many trim pieces on modern
vehicles are made of anodized aluminum. Also see Stainless steel. |
|
|
| Antenna |
A
device, usually a metal rod, which picks up radio frequencies. Antennas
are used for the radio and also mobile phones as well as CB radios.
Luxury vehicles often use retractable antennas which collapse the
antenna when the radio is not in use.
In-glass
antennas were a popular options on automobiles in the 70's and 80's.
A thin filament was inlaid in the glass of the windshield in the
form of a "T".
|
|
|
| Antifreeze |
A
liquid (typically ethylene glycol) mixed with water and added to
a vehicle's cooling system that lowers the freezing point of the
coolant and prevents the coolant from freezing. Other substances
are also added to antifreeze to prevent foaming, the formation of
rust and other deposits that could clog a radiator, and to help
lubricate items such as water pump seals.
Ethylene
glycol has a sweet smell and taste and attracts animals (pets).
When ingested, even in small amounts, pets can become very sick
and die. Never allow antifreeze to sit in an open container. New
formulations which use propylene glycol (PG) as a primary ingredient
are more pet-friendly.
|
|
|
| Anti-knock
additives |
Compounds
added to gasoline which increases the octane rating of the fuel and
helps reduce pre-detonation such as knocking and pinging. |
|
|
| Antilock
braking system (ABS) |
See
ABS (above). |
|
|
| Anti-roll
bar |
Also
called "Sway bar". A device used to improve handling and
reduce a vehicle's tendency to 'roll' during cornering. Anti-roll
bars are generally "U shaped" and made out of heavy-duty
spring steel. They can be used on both the front and rear suspensions
of vehicles. Heavy-duty aftermarket anti-roll bars are available to
help give vehicles 'race car like' handling. Also see Sway bar bushings
and Sway bar endlinks. |
|
|
| Anti-skid |
See
Antilock braking system (above). |
|
|
| Anti-sway
bar |
See
Anti-roll bar (above). |
|
|
| Anti-wheelspin |
See
Traction control system. |
|
|
| A-pillar |
A
vehicle's front vertical support pillar which supports the front portion
of the roof and also the windshield. Also referred to as the A-post. |
|
|
| Approach
angle |
Generally
applied to off-road vehicles. The maximum angle of a hill a vehicle
can climb or descend without the front end scraping or getting hung
up. Determined by drawing an imaginary line drawn from the leading
edge at the bottom of a vehicle's front tire to the lowest point of
the front end. The addition of a grill guard, winch or any protruding
component reduces a vehicle's angle of approach. Lifting a vehicle,
installing taller tires or adding a higher or closer front bumper
increases a vehicle's angle of approach making it more capable on
off-road trails. Also called Angle of approach and Angle of incline.
Also see Departure angle, Breakover angle and Airing down. |
|
|
| Aquaplaning |
See
Hydroplaning. |
|
|
| Arm
rest |
A
padded device bolted to a door panel, seat or part of a center console
that occupants can rest their arms on. Door-mounted armrests can be
used to pull the door closed with. On many automobiles, power window
and door lock switches are located in the armrest for convenient access. |
|
|
| Armature |
A
wire wrapped movable shaft inside an electric motor. When the shaft
spins in a magnetic field, an electric current is created. There are
armatures in each electric motor in a vehicle such as the starter,
alternator, heater motor, power window motors, power seat motors and
windshield wiper motor. |
|
|
| Armor
All |
A
brand name of a popular product used by restorers, detailers and car
dealers to restore the look and luster of plastics, vinyls, rubber
and painted parts. Used mostly on interior parts. |
|
|
| Aspect
ratio |
Used
in describing tire size. A tire's aspect ratio is the ratio of it's
cross sectional height to it's width. The lower the number the lower
the tire profile. A 50-series tire (sectional height 50% of it's width)
would have a lower profile than a 60 series tire. Also see P-metric
and Tire ratings. |
|
|
| Aspiration |
A
term used to describe how an engine "breathes". If the air/fuel
mixture is delivered at atmospheric pressure is it considered 'Normally
aspirated'. If an engine has a turbocharger or blower to force air
into it, it is said to be "hyperaspirated", "Blown"
or "Turbo charged". Also see Turbocharger, Supercharger,
Fuel injection, and Four-stroke cycle. |
|
|
| Assisted
steering |
See
Power steering. |
|
|
| Astro
roof |
Another
name for a sunroof used on some General Motors cars (i.e. Cadillac). |
| |
|
| Asymmetrical
tread |
Describes
the layout of a tire's tread where grooves vary across the tire's
width. For example, there might be more grooves on one edge of the
tire than another. The purpose is to provide better handling, braking,
and wear characteristics. Also see Tread grooves, Contact patch, Lugs,
Tread squirm and Alignment. |
|
|
| ATF |
A
widely used acronym that stands for automatic transmission fluid;
a specially blended type of hydraulic fluid used in automatic transmissions.
Transmission fluid is pumped under pressure through valves and channels
to engage clutches and perform shifting duties. Transmission fluid
also lubricates bearings, seals and other moving parts in the transmission.
Dextron III, designed by General Motors, is a common type of transmission
fluid used by many automobile manufacturers. Also see Dextron III
and Torque converter. |
|
|
| Audible
warning |
A
buzzer system of electronic bells a vehicle interior which chime to
warn against leaving the headlights on, leaving the keys in the ignition,
unbuckled seat belts, door ajar, etc.. Also referred to as Interior
chimes. |
| |
|
| Automatic
choke |
A
choke system that disengages automatically as opposed to a hand operated,
manual choke. Automatic chokes generally consist of a bimetalic coil
affixed to the side of the carburetor. When the engine is cold, the
coil is wound tight and turns a cam which holds the accelerator in
a slightly elevated positions (engine runs faster). As the engine
warms up, the coil is heated and expands, turning the cam back away
from the accelerator which lowers the position of the accelerator
(and rpm). Heating of the bimetalic coil usually occurs by electric
current, or heat from the exhaust manifold or cooling system. Fuel
injected engines do not use a choke. Also see Choke and Fuel injection.
|
|
|
| Automatic
climate control |
A
heating and cooling system that automatically operates the vehicle's
heater, air conditioner or ventilation system to maintain a specified
interior temperature. Some modern vehicles use sophisticated systems
that goes a step further and allows occupants to set the temperature
of ducts near them essentially allowing them to create their own unique
temperature zone. |
|
|
| Automatic
leveling |
A
suspension system that automatically compensates for added weight
in a vehicle. Such a system usually consists of air shocks or an air
bladder and sensors at each wheel. When the sensors indicate a low
ride height, an onboard air compressor pumps air into the shocks and
the vehicle rises until it reaches the proper ride height. Also see
Air springs, Air suspension and Variable rate springs. |
|
|
| Automatic
seat belt |
A
seat belt system that moves into place usually by way of an electrical
motor. A switch on the ignition or door triggers the seat belt system
to move into position. Also see Passive restraint and Retractable
seat belt. |
|
|
| Automatic
temperature control |
See
Automatic climate control (above). |
|
|
| Automatic
transmission |
A
transmission that shifts between gears with no particular extra input
from the driver to vary engine torque and rotational speed delivered
to a vehicle's wheels. A torque converter is used, along with hydraulic
pressure, to achieve shifting based on vehicle and engine speed. |
|
|
| Axle |
A
shaft which a wheel is mounted to or revolves on. An axle can be a
heavy-duty solid beam which transmits power to a wheel, or it can
also be a support between two wheels depending on application. On
a front wheel drive car, for example, each front axle would be considered
a live axle because each axle is used to drive each wheel (also
known as a half shaft). The rear beam that supports the rear
wheels would be considered a dead axle or a axle beam. Also
see Beam axle, Live axle and Constant velocity joint. |
|
|
| Axle
shaft |
The
shaft used to drive a wheel. Often a hollow axle housing supports
a set of wheels, such as used on the rear of most trucks. Such an
axle housing is hollow. Inside are solid shafts which turn and drive
the wheels. The shafts are considered axle shafts. Can also be the
shafts used to drive the wheels on a front wheel drive car. Also known
as half shafts (see Half shaft). Also see Constant velocity
joint and Live axle. |
|
|
| Axle
windup |
A
phenomenon commonly associated with rear wheel drive, solid axle vehicles
in which the torque being transmitted to the wheels is powerful enough
to cause the axle housing to rotate. It is especially common on high
horsepower vehicles where the axle is supported by leaf springs. The
springs tend to flex, allowing the housing to rotate. Axle windup
can lead to violent wheel hop as the axle winds up and unwinds. One
solution to prevent axle hop is the use of traction bars mounted to
the axle. Also see Wheel hop. |
