The bed has a chassis, four rollers arranged on the chassis, and a selectively drivable auxiliary roller (1) that is brought into contact with a floor contact. The auxiliary roller is mounted on a rigid frame (5). A drive motor (9) e.g. electric motor, is fastened to the frame, and is additionally provided for the auxiliary roller. A separate pivot drive (23) is provided for raising and lowering the auxiliary roller together with the frame relative to the chassis. The pivot drive is entirely fastened to the frame and pivots with the frame.
