Importance

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Abstract

A gate valve apparatus which includes a housing having a passageway defined therein for a fluent material, a generally planar gate, and apparatus for supporting the gate within the housing. The apparatus for supporting allows movement of the gate in opposed first and second directions that are generally parallel to the generally planar gate. The apparatus also includes an annular seal carried on the housing around the perimeter of the passageway and apparatus for moving the gate in a direction substantially perpendicular to the generally planar gate. The apparatus for moving includes a first and second shafts, the shafts have a first and second axial portions that is disposed in eccentric relationship to other axial portions of the shaft, a roller is carried on each of these eccentric portions. A roller including a bearing allowing free rotational movement is carried on each of these eccentric axial portions. The apparatus may include structure for rotating the first and second shafts to urge the rollers against the gate and move the gate to compress the seal. This apparatus may include at least a first pneumatic cylinder and a mechanical over-center linkage coupling the first pneumatic cylinder and the first and second shafts. The linkage may have a locking position which the linkage will maintain after once been attained followed by a failure of the pneumatic supply to the first pneumatic cylinder. The linkage may include an S-shaped arm fixed to the first shaft and a second arm fixed to the second shaft. Each of the various embodiments of the invention may use bearings that are needle bearings.

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First Claim