| 摘要 |
PURPOSE:To prevent a water hammer phenomenon by allowing a valve to be opened and closed at a constant speed at the perfect or the intermediate opening degree and to be gently opened and closed in the vicinity of a cloure position by permitting input operaion at a constant speed, in operating the valve. CONSTITUTION:When a handle 14 is turned clockwise at a constant speed for closing a valve 14 from the perfect opened position, a female screw member 19 and a valve rod 4 are shifted integrally in the closing direction, and the closing speed becomes max. at the perfect or the intermediate opening degree, during closing process. In the vicinity of closure position, when a roller 28 reaches an inclined groove 27b or 27c, the speed for the valve rod 4 to shift in the direction of closure is reduced by the inclined grooves 27b and 27c, and a valve piece 2 gently closes a valve port 3, and a water hammer phenomenon is prevented. |
