| 摘要 |
A pneumatic or hydraulic rotary drive, in particular for a shut-off valve such as a ball shut-off valve, has a power cylinder, the piston stroke of which can be converted via screw gearing into the rotary movement of an output member connected to the shut-off cock in such a way as to be fixed in terms of rotation. The power cylinder has a central piston rod (62) with a diametral transverse pin (72) which projects through pairs of slotted holes in two concentric control sleeves (44, 54) held against axial displacement. The outer control sleeve (44) is held against rotation and the inner control sleeve (54) forms the output member. Both control sleeves contain slotted holes which in one control sleeve (54) are designed to be straight and in the other control sleeve (44) run helically about the axis thereof. The rotary drive thereby obtained is exceptionally compact and insensitive to contamination. <IMAGE> |
