wheelDrive

Wheeldrive refers to the system by which a vehicle transmits engine or motor torque to its wheels. The configuration of wheel drive determines which wheels provide propulsion and how power is distributed, influencing traction, handling, and efficiency. The most common arrangements are front-wheel drive (FWD) and rear-wheel drive (RWD), while all-wheel drive (AWD) and four-wheel drive (4WD) are designed to deliver power to more than one axle. In two-wheel-drive vehicles only two wheels receive drive torque, typically the front pair in FWD or the rear pair in RWD.

Front-wheel drive sends torque to the front wheels, contributing to compactness and efficiency with usually lighter weight. Rear-wheel drive directs power to the rear wheels, often associated with balanced weight distribution and traditional handling. All-wheel drive generally provides power to both axles, with a center differential to manage speed differences, improving traction on slippery surfaces. Four-wheel drive refers to a system with transfer gears that can send torque to both axles, often with selectable high/low ranges for off-road use; some 4WD systems are part-time, others are full-time.

Mechanisms commonly involved include differentials, which allow wheels on the same axle to rotate at different speeds, and, in AWD/4WD, a center differential or transfer case to distribute torque between axles. Limited-slip and electronically controlled brakes or traction-control systems further modulate torque to individual wheels. Electric vehicles may use distributed propulsion with a motor at one or more wheels, enabling independent wheel torque control without a mechanical differential; in-wheel motors are an example.

Historically, RWD dominated early automobiles, with FWD becoming widespread in mid-to-late 20th century for compact and economical cars. AWD and 4WD gained traction in performance cars, SUVs, and trucks for all-weather and off-road capability. The choice of wheeldrive affects ride, efficiency, weight, and maintenance requirements, and is often tailored to vehicle purpose and expected driving conditions.