| 摘要 |
A ball valve having a cam element, and a ball having a left arm and a right arm with a slot between each arm. A terminal portion of each arm is positioned adjacent the cam element. The cam element is shaped so that, when the ball is rotated from the open condition to the closed condition, the cam element forces the arms through three distances of separation. A first distance, when the ball has undergone no rotation from the fully open condition. A second distance, when the ball has undergone some rotation from the fully open condition towards the closed condition but has not reached the closed condition. A third distance in which the ball has undergone rotation to the closed condition. The third distance is greater than the first distance, and the second distance is greater than the third distance. |
