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Fail operative split tandem valve

  • US 3,933,176 A
  • Filed: 07/12/1974
  • Issued: 01/20/1976
  • Est. Priority Date: 07/12/1974
  • Status: Expired due to Term
First Claim
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1. A fail operative valve for simultaneous valving in two separate systems including:

  • a valve housing having first and second portions, said first housing portion having an inlet for pressurized fluid, at least one outlet for fluid return and a pair of ports for feeding the fluid to and from actuator means, said second housing portion having an inlet for pressurized fluid, at least one outlet for fluid return and a pair of ports for feeding the fluid to and from actuator means;

    a first valve slide positioned in said first housing portion adjacent said first housing portion inlet, outlet and ports, said first valve slide having first and second annular passageways which are the only annular passageways therein, said first and second passageways normally valving said hydraulic fluid between said first housing portion inlet, outlet and ports to operate the actuator means, said first valve slide also having a third passageway connected to said first passageway and a fourth passageway connected to said second passageway;

    a second valve slide positioned in said second housing portion adjacent said second housing portion inlet, outlet and ports, said second valve slide having first and second annular passageways which are the only annular passageways therein, said first and second passageways normally valving said hydraulic fluid between said second housing portion inlet, outlet and ports to operate the actuator means, said second valve slide also having a third passageway connected to said first passageway and a fourth passageway connected to said second passsageway; and

    bypass driver means having a connection for mechanical input commands, first preloaded resilient means connected to move said first valve slide with said bypass driver means in response to the mechanical input commands up to a predetermined force, second preloaded resilient means connected to move said second valve slide with said bypass driver means in response to the mechanical input commands up to a predetermined force, a first pair of passageways positioned to complete a bypass flow channel between said first valve slide third and fourth passageways when the predetermined force is exceeded and said bypass driver means are moved by said mechanical input with respect to said first valve slide, and a second pair of passageways positioned to complete a bypass flow channel between said second valve slide third and fourth passageways when the predetermined force is exceeded and said bypass driver means are moved by said mechanical input with respect to said second valve slide, said first and second passageways of said first and second valve slides being positioned to always be in communication with said pair of ports for feeding fluid to and from the actuator means so a jam of one of said valve slides to said valve housing cannot produce hydraulic lock of the actuator means and said first and second valve slides having concentric inner and outer cylindrical surfaces, said first and second passageways thereof being annular channels in said outer cylindrical surfaces and said bypass driving means being positioned in contact with said inner cylindrical surfaces, said bypass driver means having at least one cylindrical outer surface, said first pair of passageways of said bypass driving means being annular channels in said cylindrical outer surface thereof, said fourth passageways of said first and second valve slides being positioned to always be in communication with said pairs of passageways in said bypass driving means and said third passageways of said first and second valve slides being positioned to be in communication with said pair of passageways in said bypass driving means only when the preload of said respective preloaded resilient means is exceeded.

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