Four-wheel drive
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A four-wheel drive, also called 4×4 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.
The Jeep Wrangler (pictured is a TJ Wrangler) is a 4WD vehicle with a transfer case to select low-range or high-range four-wheel drive.
Center transfer case sending power from the transmission to the rear axle (right) and front axle (left)
The Lamborghini Murciélago is an AWD that powers the front via a viscous coupling unit if the rear slips
The HMMWV is a 4WD/AWD that powers all wheels evenly (continuously) via a manually lockable center differential, with Torsen differentials for both front and rear
Drive shaft
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A drive shaft, driveshaft, driving shaft, tailshaft, propeller shaft, or Cardan shaft is a component for transmitting mechanical power, torque, and rotation, usually used to connect other components of a drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them.
Drive shaft with universal joints at each end and a spline in the centre
Škoda 422 rear axle, suspension and drive shaft on display at the Škoda Museum
A truck two section propeller shaft
The exposed drive shaft on BMW's first motorcycle, the R32