A differential transfers power (more accurately, torque) from the transmission or transfer gearbox to the axles/wheels, and allows the axles and wheels to turn at different speeds (so the vehicle can turn corners without drivetrain wind-up – the wheels on the outside of a curve turn faster and travel a greater distance than the inside wheels). While most differentials are mechanical gear-driven devices, sometimes a viscous coupling (VCU) or a multi-late transfer clutch pack (MPT) can act in place of a differential.