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Electro-hydraulic directional control valve

  • US 4,543,875 A
  • Filed: 11/30/1983
  • Issued: 10/01/1985
  • Est. Priority Date: 12/07/1982
  • Status: Expired due to Fees
First Claim
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1. An electro-hydraulic directional control valve comprising a main control valve for controlling the communication between a pressure source, a hydraulic actuator and a fluid reservoir, said main control valve including a main control spool supported for reciprocation, springs acting on opposite ends of said main control valve spool for urging said main control valve in a centered position, a control pressure chamber formed at one end of said main control valve spool for urging said main control valve spool axially in a first direction upon pressurization of said control pressure chamber and for urging of said main control valve spool in the opposite direction upon the communication of said control pressure chamber with said reservoir, a pilot control valve including a spring biased pilot control spool and a proportional solenoid for actuating said pilot control spool against the action of said spring, said pilot control spool being movable from a neutral position toward either side thereof to respective first and second operating positions, said pilot control valve spool being operative in said first position to pressurize said control pressure chamber and in said second position being operative to communicate said control pressure chamber with said reservoir, said spring biased pilot control spool being urged to a neutral position by said spring, the improvement comprising means forming a pressure chamber acting on said main control valve spool in a direction opposite to said control pressure chamber, and means to pressurize said control pressure chamber and said pressure chamber when said spring urges said pilot control valve spool to its neutral position for maintaining said main control valve spool in a neutral position and for communicating said pressure chamber with said reservoir when said pilot control valve spool is in said first and second operating position.

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