| 摘要 |
982,488. Valves. ROCKWELL MANUFACTURING CO. Dec. 21, 1962 [Jan. 9, 1962], No. 48375/62. Heading F2V. A rotary spherical valve has its stem 28, Fig. 2, rotated through a toggle mechanism 30 by a pair of actuators 32, 34, each consisting of a pair of cylinders 36, 38 housing pistons 40 connected by a rod 42. The valve is operated by supplying liquid to opposite cylinders in the two operators from a hand pump 45 via a four-way valve 46; alternatively the pistons may be moved by air or gas from the line controlled by the valve or from a compressor or tank under the control of another four-way valve 50. A valve position indicator 58 is provided. The toggle mechanism 30, Fig. 3, consists of a crank 60 keyed to the stem 28, the crank housing spaced arms 62, 64 pivotally mounting links 72, 74, each pair of the latter being connected to one of the two operator rods 42 by a pin 82. The angle between the arms and links changes as the valve is moved from the closed to open position after which the torque needed falls below that necessary at the beginning of the opening movement. In a modification, the stem is rotated via a toggle mechanism by a screw 94, Fig. 8, actuated by manual hydraulic, pneumatic or electric means through speed-reducing means, and connected by a follower 134 to the ends of links 122, 124 which are pivotally attached to the spaced arms 116, 118 of an asymmetrical crank 114 connected to the stem. The actuator may be provided with positional and torque limit switches. U.S.A. Specifications 2,809,011 and 3,056,573 are referred to. |
