Patent ID: 7802851

Claim:
A method for adjusting mutual position of two structural elements of a patient chair, which structural elements are connected to each other by an articulated shaft, in which method said mutual position of said two structural elements is adjusted by a drive device arranged to produce a linear motion, which linear motion is converted to a slow rotational motion of a first thread element arranged in connection with said articulated shaft, wherein said linear motion is produced with the help of the drive device producing rotational motion and of a second thread element which changes the rotational motion to an axial motion on said articulated shaft, wherein an essentially fast rotational motion is produced by said drive device to said second thread element, and wherein said essentially fast rotational motion produced by the drive device is converted to a linear motion of said first thread element in said second thread element by an essentially low-pitched thread element, which linear motion is further converted, in said first thread element and with the help of essentially high-pitched threads on the articulated shaft, to an essentially slow rotational motion of the first thread element.