| 摘要 |
The assembly 10 includes a bonnet housing 40 which is attached to a body 11 of the gate valve and has a central bore 43 and a chamber 45 along the central bore. A valve stem 48 is movably positioned within bore 43 and coupled to gate 30 and to a valve actuator 50. A piston 60 is slideably received on the valve stem 48 and is positioned within chamber 45. The piston includes at least one damping hole 64. A flange 70 is attached to the valve stem and abuts against piston 60 to move the piston when the valve stem 48 is moved from the closed position to the open position. A spring 74 is provided for independently moving the piston 60 to the original position when the valve stem 48 is moved from the open position to the closed position, and the flange 70 leaves contact with the piston 60, allowing rapid undamped closure of the gate 30. |
