four-wheel drive v. all-wheel drive
Wednesday, December 2, 2009 Four-wheel drive (4WD) and all-wheel drive (AWD) systems allow a vehicle’s engine to provide torque to all four wheels simultaneously.
Four-wheel drive is a part-time system that can be switched manually between two-wheel drive and four-wheel drive modes. 4WD is usually found on trucks and off-road vehicles, and improves handling on low traction surfaces like ice, snow, mud, or gravel. When engaged, the front and rear wheels rotate at the same speed.
All-wheel drive is implemented in on-road consumer vehicles like sedans and SUVs. In an all-wheel drive system, all four wheels are always being driven by the engine. AWD can be used on dry pavement without the tires slipping thanks to a center differential, which enables the front and rear axles to rotate at different speeds.