A drive arrangement for a shaft has a module carried by the shaft and including a motor, a driven wheel and a drive wheel. The motor, gearbox and drive wheel are carried on a slider plate which can slide transverse to the axis of the shaft. A front plate is fixed transverse to the axis of the shaft. A Bowden cable has its sheath attached to the front plate, and its inner cable attached to the slider plate, so that manipulation of the Bowden cable at a remote location allows force to be applied between the plates either tightening the belt to apply drive from the motor to the shaft, or releasing tension in the belt, to disengage the drive.