Six-wheel drive


Six-wheel drive is an all-wheel drive drivetrain configuration of three axles with at least two wheels on each axle capable of being driven simultaneously by the vehicle's engine. Unlike four-wheel drive drivetrains, the configuration is largely confined to heavy-duty off-road and military vehicles, such as all-terrain vehicles, armored vehicles, and prime movers.
6×6 with three evenly spaced axles and full-time 6x6 H-drive
When such a vehicle only has six wheels by definition all are driven. When it has ten - with two pairs of ganged "dual" wheels on each rear axle as on a GMC CCKW - all are also driven but the 6×6 designation remains. For most military applications where traction/mobility are considered more important than payload capability, single wheels on each axle are the norm.
Heavy hauler and ballast tractor 6×6s have had a long history as prime movers both in the military, and commercially in logging and heavy equipment hauling both on- and off-road.
Most six-wheel drive vehicles have a forward axle and two at the rear, or three evenly spaced in varying steering configurations. Depending on the vehicle's role, the number of wheels varies between six and ten. Drive may be limited to the rear two axles for on-road use.

Examples

Military
Military/commercial
Commercial
Conversions
Recreational ATV/UTV
, testbed, and limited production commercial examples include:
Twin front axle
Twin rear axle
drive in the rear, and an integrated "roll steer" function built into the suspension design. All 6x6 Australia Pty Ltd vehicles are ADR-compliant with IPA for both "heavy" and "light" vehicles.