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US Patent: 4,658,859
Valve Spool with Cross Drill Ports
Bengt S. Backe - Dundee, IL
LaMoyne W. Durham - Bartlet, IL

USPTO Classifications:
137/625.22, 137/625.23, 137/625.47, 251/283

Tool Categories:

South Bend Lathe, Inc. - South Bend, IN

Not known to have been produced

none listed

Patent Dates:
Applied: Dec. 07, 1984
Granted: Apr. 21, 1987

Patent Pictures:
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South Bend Lathe History
"Vintage Machinery" entry for South Bend Lathe Works
Barnes & Thornburg - patent attorneys


A four-way valve is provided, for selectively interconnecting pressure supply and return lines with control pressure lines of a hydraulic device, having means for independently balancing the valve against pressures exerted on the valve by any one or more of the pressure lines and at any operating position of the valve. These pressures exerted on the valve would otherwise restrict or prevent actuation of that valve. This balancing means exposes a minimum surface area of the valve to high pressure forces and isolates the fluid pressure in the pressure lines until interconnection is made by valve actuation.

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