| 摘要 |
PURPOSE:To protect the drive means from being applied with heavy load when starting, by providing a relatively slidable valve body on a valve rod not to be removed while stretching spring means between a member fixed to the valve rod and the valve body. CONSTITUTION:When a valve body 3 is in close position, the valve rod 4 is displaced through drive means 7 to the position rearer by predetermined distance from the position of valve seat 10. Under this condition, the valve body 3 is pressed through a spring 6 against the valve seat 10 thus to stop the flow reliably. The pressing force of valve body 3 is regulated by regulating the displacement of valve rod 4. Consequently, even upon application of voltage across a motor to start displacement of valve rod 4 in open-valve direction, the valve body 3 will maintain the valve close position until a stopper ring 13 will contact against the valve body 3 thus to prevent application of load onto the motor when starting.
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