fig3 of the drawing shows the basic structure of the actuator the part a is applied as a standard unit as mentioned while the part b may be adapted to customer specific wishes the end of the rear mount 8 of the actuator which is seated in the cabinet is mounted in a mounting element 40 of hexagonal cross section which is received in a corresponding recess in the end cover of the cabinet fig6 and 11 the rear mount may thus be rotated in steps of 30 u00b0 for adaptation of its position to the structure in which the actuator is incorporated the mounting element consists of two parts 40 a 40 b which are assembled around the rear mount 8 which is secured in that a flange on the element 40 engages a groove in the rear mount the element 40 also includes a seat for a ball bearing 41 secured via a bushing on the shaft of the spindle the bearing is secured against a breast on the bushing 43 and a head 44 mounted on the outer end of the shaft the mounting element 40 with the spindle unit 4 is secured to the cover 1 a by a nut 42 on the part of the rear mount which protrudes from it and is fixed against the outer side of the cover the rear mount 8 has a cylinder element with an eye 45 but it will be appreciated that the actuator may be provided with customer specific rear mounts as mentioned.