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Two stage kneeling valve

  • US 5,544,688 A
  • Filed: 12/23/1994
  • Issued: 08/13/1996
  • Est. Priority Date: 12/23/1994
  • Status: Expired due to Term
First Claim
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1. A valve assembly comprising:

  • a body including;

    a first port in fluid communication with a volume of pressurized fluid;

    a second port fluidly connected to a source of pressurized fluid for increasing the fluid pressure in said volume; and

    a third port for controlling the venting of pressurized fluid from said volume to the atmosphere;

    a first valve member disposed in said body and movable to alternately allow and prevent fluid flow between said first and second ports;

    a second valve member movably disposed substantially within said first valve member to selectively permit fluid flow from said first port to said vent port when said first valve member prohibits fluid flow between said first and second ports;

    first biasing means for bringing the fluid pressure in said volume to a first predetermined pressure by acting upon said second valve member to allow fluid flow until pressure at said first port is insufficient to overcome the force exerted by said first biasing means; and

    second biasing means for selectively acting in cooperation with said first biasing means to bring said volume pressure to a second predetermined pressure by allowing fluid flow until pressure at said first port is insufficient to overcome the force exerted by the combination of said first and second biasing means.

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