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Full-time 4WD
Although in the strictest sense, the term "four-wheel drive" refers to a capability that a vehicle may have, it is also used to denote the entire vehicle itself. In Australia, vehicles without significant offroad capabilities are often referred to as All-Wheel Drives (AWD) or SUVs, while those with offroad capabilities are referred to as "four-wheel drives". This term is sometimes also used in North America, somewhat interchangeably for SUVs and pickup trucks and is sometimes erroneously applied to two-wheel-drive variants of these vehicles.
The term 4x4 is used to denote the total number of wheels on a vehicle and the number of driven wheels; it is often applied to vehicles equipped with either Full-time 4WDor Part-time 4WD. The term 4x4 is common in North America and is generally used when marketing a new or used vehicle, and is sometimes applied as badging on a vehicle equipped with four-wheel drive.
Similarly, a 4x2 would be appropriate for most two-wheel-drive vehicles, although this is rarely used in the USA in practice. In Australia the term is often used to describe utes that sit very high on their suspension. This is to avoid the confusion that the vehicle might be a 4x4 because it appears to be otherwise suited to off-road applications. A 2×4, however, is unambiguously a piece of lumber.
The Full-time in Full-time four-wheel drive means that four-wheel drive is engaged at all times no matter whether the surface of the road.4wd_demystified/fulltime.tmpl A center differential that allows the front and rear wheels to rotate at different speeds differentiates the full-time and the part-time system. Unless, the vehicle has a a locking center differential, the 50/50 power split can deteriorate by the abilty to drive on dry pavement.
Select-Trac, a four-wheel driveline offerd by Jeep, offers drivers 4WD Full-time, 4WD Part-time (center differential locked), 4WD Low-range and 2WD. Select-Trac does not use automatic-locking hubs, but rather, the front driveshaft and axle rotate with the wheels at all times.
External Links
4wd_turbo_cars.html RallyCars Article on Full-time 4 Wheel Drive
