Abstract: A drive assembly for a valve includes a motor, a transmission which is coupled to the motor and the valve, and a manual drive unit having a shaft which is arranged to be driven by a handwheel. The shaft has a small amount of axial play and is provided with a worm. The transmission includes a hollow gear having internal teeth coupled to the motor shaft and external teeth in permanent mesh with the worm. A membranous disc is mounted on the worm shaft in such a manner that the outer margin of the disc is held against displacement in axial direction of the worm shaft while the central portion of the disc adjacent the worm shaft is fixed against axial displacement relative to the worm shaft. However, the worm shaft can rotate relative to the disc. Strain gages in the form of strips are mounted on one side of the disc and are connected to an integrated circuit on the same side of the disc.