Open the process

1, in the closed position, the sphere of stem [/ wiki] [wiki] machinery pressure function, press the seat.
2, when turn the handwheel counterclockwise, the valve stem is reverse movement, the Angle at the bottom of the plane to make the ball off the seat. 
3, stem continue to ascend, and valve stem guide pin of interaction in the spiral groove, the sphere began to rotate without some friction. 
4, until to the fully open position, the valve stem to limit position, sphere rotation to the full open position.

Close the process

1, closing, rotating the handwheel clockwise, stem began to drop and the ball left seat begin to spin. 
2, continue to rotate the handwheel, the valve stem is embedded in the spiral groove on the role of the guide pin, the stem and ball rotate 90 ° at the same time. 
3, almost closing, sphere has been without contact with the valve seat rotated 90 °. 
4, the hand wheel rotation of the last few laps, stem mechanically wedge Angle at the bottom of the plane to the oppression of sphere, make its strong pressure on the seat, to completely seal.