| 摘要 |
A gate valve for selectively blocking and unblocking a flow path has a valve body filled with hydraulic liquid and provided with a pair of shutters displaceable by fluid pressure against respective seating surfaces of a valve housing. The valve body is shiftable between a blocking position, in which the shutters are aligned with their seating surfaces, and an unblocking position by means of a plunger projecting into the hollow body in a fluidtight manner but with freedom of relative displacement in the shifting direction. In a valve-closing stroke, the plunger pushes that body into its blocking position solely via the confined liquid; when the body is arrested in that position by a stop, the continuing plunger stroke displaces the liquid to press the shutters onto their seats against a biasing force such as that of elastic membranes holding them onto the body. In a valve-opening stroke, the receding plunger hydraulically withdraws the shutters from their seats and then retracts the valve body into its unblocking position.
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