All-wheel drive vehicle
An all-wheel drive[1] vehicle (AWD[2] vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand.
Types
[edit]The most common forms of all-wheel drive are:
- 1x1
- All unicycles
Reflects one axle with one wheel capable of being powered. - 2x2
- Some motorcycles and bikes
Reflects two axles with one wheel on each capable of being powered. - 4×4 (also, four-wheel drive or 4WD)
- Reflects two axles with both wheels on each capable of being powered.
- 6×6 (also, six-wheel drive or 6WD)
- Reflects three axles with both wheels on each capable of being powered.
- 8×8 (also, eight-wheel drive or 8WD)
- Reflects four axles with both wheels on each capable of being powered.
Vehicles may be either part-time all-wheel drive or full-time:
- On-demand or Part-time
- One axle is permanently connected to the drive, the other is connected as needed
- Full-time or Permanent
- All axles are permanently connected, with or without a differential.
- Independent
- The wheels are driven, but not dependent on a central mechanical power coupling.
Terminology
[edit]In the context of hybrid and electric vehicles, the North American designation of 'all-wheel-drive' may differ. In some hybrid vehicles, the combustion engine is only mechanically connected to the front wheels, while the rear wheels are powered independently by an electric motor; this may be marketed as eAWD. Furthermore, many electric vehicles have individual, unconnected motors powering each axle, or even each individual wheel, also without any center differential.
Characteristics
[edit]When tire grip is good during road driving, a differential is used between the axles to avoid driveline windup. This is not required off-road, as the limited grip allows the tires to slip. All-wheel drive vehicles designed for extensive off-road use may not have such a differential, and so they suffer from wind-up when used on-road.[3] Selectable 4WD also avoids this problem and requires only a simple dog clutch in the transfer case, rather than a differential. For this reason, most early off-road vehicles used that system; e.g., Jeep, Land Rover.
As vehicles became more sophisticated and tires gave better winter performance in the 1960s, there was an interest in giving the benefits of all-wheel drive to conventional cars: not for off-road use but for winter use in snow and ice or on wet roads. Exotic vehicles such as the high-powered Jensen FF followed by the AMC Eagle, Subaru Leone and Audi Quattro series were the first to offer all-wheel drive in a high-speed road-based car. These, particularly the Quattro, would extensively develop this drivetrain with the use of viscous couplings and differentials to provide a safe and drivable car. The first off-road / on-road hybrids such as the Range Rover also chose the permanent all-wheel-drive system rather than manual selection.
See also
[edit]- All-terrain vehicle
- Four Wheel Drive or FWD, one of the first companies, from 1909, to build four-wheel drive vehicles.
- Front-wheel drive
- H-drive
- Individual wheel drive (IWD)
- Rear-wheel drive
- Two-wheel drive
References
[edit]
- ^ Meyer, Donald E. "The first century of GMC truck history" (PDF). Archived from the original (PDF) on 9 January 2014 – via GM Heritage Center.
By December [1939], GMC had orders for more than 4,400 all-wheel-drive military trucks.
- ^ "Automotive History". allisons.org. Australia. Retrieved 24 October 2024.
1929: AEC started to build AWD trucks in conjunction with FWD (UK)
- ^ Ware, Pat (1994). In National Service. Warehouse Publications. p. 118. ISBN 0-9525563-0-8.
External links
[edit]- "All Wheel Drive Motorcycles 2x2". Fuel. 23 January 2021. Retrieved 28 September 2025.
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