| 摘要 |
A valve (10) for controlling fluid flow to and from an actuatable device (30) includes a housing (34) defining a chamber (90) for establishing fluid communication between a fluid supply (14) and the actuatable device (30). A spherical ball (120) controls fluid flow through the chamber (90). The housing (34) has a housing seat (84) on which the ball (120) can be seated. A piston (100) movable in the chamber (90) in response to a control input has a piston seat (106) on which the valve element (120) can be seated. The valve (10) has an exhaust condition in which the ball (120) is seated on the housing seat (84) and is spaced apart from the piston seat (106), and a supply condition in which the ball is seated on the piston seat and is spaced apart from the housing seat, and a hold condition in which the ball (120) is seated on the housing seat (84) and the piston seat (106) is seated against the ball (120) simultaneously.
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