Patent ID: 7047866
Filing Date: 2006-05-23
Classification: E02F,F15B

Abstract:
1. A hydraulic control circuit for an attachment coupling system, said control circuit comprising: an input flow path for receiving a supply of pressurized fluid; first and second actuator flow paths for supplying fluid to respective first and second input/output locations of a first hydraulic actuator; a return flow path for supplying pressurized fluid to a reservoir; a pilot pressure path adapted for connection to an associated attachment positioning device that outputs a varying pilot pressure of said pressurized fluid from said input flow path to said pilot pressure path in response to operator input; a first control valve connected to said input flow path, said return flow path, and said first and second actuator flow paths, said first control valve selectively positionable in at least first and second states in response to first electrical input wherein: (i) in said first state, said first control valve connects said input flow path to said first actuator flow path and connects said return flow path to said second actuator flow path; and, (ii) in said second state, said first control valve connects said input flow path to said second actuator flow path and connects said return flow path to said first actuator flow path; a first pressure sensor for sensing fluid pressure in said input path meeting or exceeding a first threshold; a second pressure sensor for sensing fluid pressure in said pilot pressure path meeting or exceeding a second threshold; wherein said first and second pressure sensors control said first electrical input to said first control valve to prevent a change of state of said first control valve depending upon fluid pressure in said input path and said pilot pressure path, respectively.