4 Wheel Drive

A four-wheel drive, also called 4×4 ("four by four") or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges.
A four-wheel drive vehicle with torque supplied to both axles is described as "all-wheel drive" (AWD). However, "four-wheel drive" typically refers to a set of specific components... meer