First, the opening process
1 In the closed position, the ball is pressed against the seat by the [wiki] mechanical [/wiki] pressure of the stem.
2. When the handwheel is turned counterclockwise, the stem moves in reverse, and the angular plane at the bottom makes the ball free from the seat.
3 The stem continues to lift and interact with the guide pin in the stem spiral groove to begin a frictionless rotation of the ball.
4 Until it reaches the fully open position, the stem is raised to the limit position, and the ball is rotated to the fully open position.
Two, the closing process
1 When closing, turn the handwheel clockwise, the stem begins to drop and the ball starts to rotate away from the seat.
2 Continue rotating the handwheel, and the stem is subjected to the action of the guide pin embedded in its upper spiral groove, causing the stem and ball to rotate 90° at the same time.
3 When close, the ball has rotated 90° without contact with the seat.
4 For the last few turns of the hand wheel, the angular plane at the bottom of the stem is mechanically wedged to press the ball tightly against the seat to achieve a complete seal.
