A drive wheel is a roadwheel in an automotive vehicle that receives torque from the powertrain, and provides the final driving force for a vehicle. A two-wheel drive vehicle has two driven wheels, and a four-wheel drive 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.
Drive wheel configurations
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- 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 drive, 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 vehicle with a drivetrain that allows all four roadwheels to receive torque from the internal combustion engine simultaneously. While some people associate the term with off-road vehicles - powering all four wheels provides better control, and therefore safety on slick ice, and is an important part of rally racing on mostly-paved roads.
Front-wheel drive (or FWD for short) is the most common form of internal combustion engine / transmission layout used in modern passenger cars, where the engine drives the front wheels. Most front wheel drive vehicles today feature transverse engine mounting, whereas in past decades engines were mostly positioned longitudinally instead. Rear-wheel drive was the traditional standard, and is still widely used in luxury cars and most sport cars. Four-wheel drive is also sometimes used. See also Front-engine, front-wheel drive layout.
Rear-wheel drive (or RWD for short) was a common internal combustion engine / transmission layout used in automobiles throughout the 20th century. RWD typically places the engine in the front of the vehicle, but the mid engine and rear engine layouts are also used.
- Drive sprocket, the powered sprocket on a tracked vehicle
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