Constant-velocity joint

A constant-velocity joint (also called a CV joint) is a mechanical coupling which allows the shafts to rotate freely (without an appreciable increase in friction or backlash) and compensates for the angle between the two shafts, within a certain range, to maintain the same velocity.

A common use of CV joints is in front-wheel drive vehicles, where they are used to transfer the engine's power to the wheels, even as the angle of the driveshaft varies due to the operation of the suspension.