A
drive wheel is a
roadwheelA wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle,...
in an automotive
vehicleA vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....
that receives
torqueTorque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
from the
powertrainIn a motor vehicle, the term powertrain or powerplant refers to the group of components that generate power and deliver it to the road surface, water, or air. This includes the engine, transmission, drive shafts, differentials, and the final drive...
, and provides the final driving force for a vehicle. A
two-wheel driveTwo wheel drive or 2WD describes vehicles with a drivetrain that allows two wheels to receive power from the engine simultaneously.-Four wheeled vehicles:...
vehicle has two driven wheels, and a
four-wheel driveFour-wheel drive, 4WD, or 4×4 is a four-wheeled vehicle with a drivetrain that allows all four wheels to receive torque from the engine simultaneously...
has four, and so-on.
A
steer wheel is one that turns to change the direction of a vehicle. A
trailer wheel is one that is neither a drive wheel nor a steer wheel.
Two-wheel drive
For four-wheeled vehicles, this term is used to describe vehicles that are able to transmit torque to at most two roadwheels, referred to as either
front-Front-wheel drive is a form of engine/transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longitudinal engine arrangement generally found in rear-wheel drive and...
or rear-wheel drive. The term
4x2 is also used, to indicate four total road-wheels with two being driven.
For vehicles that have part-time
four-wheel driveFour-wheel drive, 4WD, or 4×4 is a four-wheeled vehicle with a drivetrain that allows all four wheels to receive torque from the engine simultaneously...
, the term "Two-wheel drive" refers to the mode when 4WD is deactivated and torque is applied to only two wheels.
Four-wheel drive or All-wheel drive
Four-wheel drive,
4WD,
4x4 ("four-by-four"),
all-wheel drive, and
AWD are terms used to describe a four-wheeled
vehicleA vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....
with a drivetrain that allows all four
roadwheelsA wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle,...
to receive torque from the
internal combustion engineThe internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
simultaneously. While some people associate the term with
off-road vehicleAn off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with deep, open treads, a flexible suspension, or even caterpillar tracks...
s - powering all four wheels provides better control, and therefore safety on slick ice, and is an important part of
rally racingRallying, also known as rally racing, is a form of auto racing that takes place on public or private roads with modified production or specially built road-legal cars...
on mostly-paved roads.
Front-wheel drive
Front-wheel drive (or FWD for short) is the most common form of
internal combustion engineThe internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
/
transmissionA machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...
layout used in modern
passenger carAn automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s, where the engine drives the front
wheelA wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle,...
s. Most front wheel drive vehicles today feature
transverse engineA transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the long axis of the vehicle. Many modern front wheel drive vehicles use this engine mounting configuration...
mounting, whereas in past decades engines were mostly positioned
longitudinallyIn automotive engineering, a longitudinal engine is an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, front to back....
instead. Rear-wheel drive was the traditional standard, and is still widely used in luxury cars and most sport cars.
Four-wheel driveFour-wheel drive, 4WD, or 4×4 is a four-wheeled vehicle with a drivetrain that allows all four wheels to receive torque from the engine simultaneously...
is also sometimes used. See also Front-engine, front-wheel drive layout.
Rear-wheel drive
Rear-wheel drive (or
RWD for short) was a common
internal combustion engineThe internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
/
transmissionA machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...
layout used in
automobileAn automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s throughout the 20th century. RWD typically places the engine in the
frontA front-mounted engine describes the placement of an automobile engine in front of the vehicle passenger compartment.Historically, this designation was used regardless of whether or not the entire engine was behind the front axle line...
of the vehicle, but the mid engine and rear engine layouts are also used.
See also
- Drive sprocket, the powered sprocket on a tracked vehicle