主权项 |
1. A mud valve comprising:
a) an annular frame having a lower surface forming a flange, and an upper surface with an open center having an inner circumference forming a seating surface with a seat angle relative to the upper surface of the annular frame; b) a yoke having an arch with an apex, a first arm with an inner surface and an end, and a second arm with an inner surface and an end; the inner surface of the first arm having a guide rail with a thickness, and the inner surface of the second arm having a guide rail with a thickness; the end of the first yoke arm and the end of the second yoke arm being permanently connected to the upper surface of the annular frame; c) a valve plug having a diameter with a first end and a second end, an upper surface, a lower surface with a circumference, and a seating surface on the circumference of the lower surface of the valve plug having a seat angle corresponding to the seat angle of the inner circumference of the annular frame; d) a first pair of tabs comprising a first tab mounted on the upper surface of the valve plug with a lower edge of the first tab at a first distance from the upper surface of the valve plug and a second tab mounted on the upper surface of the valve plug with a lower edge of the second tab at a second distance from the upper surface of the valve plug which is greater than the first distance, the first tab and the second tab being at opposite sides of the first end of the diameter, the pair of tabs extending radially past the first end of the diameter of the valve plug and being separated from each other by a distance at least as great as the thickness of the guide rail on the inner surface the first arm of the yoke; e) a second pair of tabs comprising a first tab mounted on the upper surface of the valve plug with a lower edge of the first tab at a first distance from the upper surface of the valve plug and a second tab mounted on the upper surface of the valve plug with a lower edge of the second tab at a second distance from the upper surface of the valve plug which is greater than the first distance, the first tab and the second tab being at opposite sides of the second end of the diameter, the pair of tabs extending radially past the second end of the diameter of the valve plug and being separated from each other by a distance at least as great as the thickness of the guide rail on the inner surface the second arm of the yoke; the first tab of the second pair of tabs being on a same side of the diameter as the first tab of the first pair of tabs, and the second tab of the second pair of tabs being on a same side of the diameter as the second tab of the first pair of tabs; f) a valve stem passing through the apex of the yoke and having an end coupled to the upper surface of the valve plug; and wherein a distance between an upper edge of each first tab and a lower edge of each second tab in each of the pairs of tabs being at least as great as the thickness of the guide rail on the inner surface of the yoke. |