Spool valve
Patent 4593719 Issued on June 10, 1986. Estimated Expiration Date: 
November 30, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
November 30, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2600348 2655940 2966891 2982306 3219060 3269417 3339572 3502109 3508584 Fluidic repeater InventorApplicationNo. 06/676702 filed on 11/30/1984US Classes:137/625.66, Fluid motor137/625.63, Common to plural valve motor chambers137/625.64ElectricExaminersPrimary: Michalsky, Gerald A.Attorney, Agent or FirmInternational ClassesF16K 3/00 (20060101)F16K 3/36 (20060101) F16K 11/07 (20060101) F16K 11/065 (20060101) AbstractA high frequency four-way valve reciprocated by hydromechanical amplifiers has its amplifier volumes volume compensated by passage means in each valve spool end connecting each amplifier volume with the adjacent outlet port. In a modification, there are longitudinally extending grooves on the outer periphery of each drive piston, one group of longitudinal grooves connecting the amplifier volume with the annular lubrication grooves around the piston and another group of longitudinal grooves connecting the annular grooves with the adjacent outlet port. The longitudinal grooves supply lubricant to the annular grooves, and also enhance the volume compensation.Other References
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