Patent ID: 7367256

Claim:
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 associated with an attachment coupler; a return flow path for supplying pressurized fluid to a reservoir; 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 a first electrical control signal 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 pressure sensor for sensing fluid pressure supplied to an associated attachment positioning cylinder, said pressure sensor adapted to output an electrical pressure signal that changes state when said fluid pressure supplied to the associated attachment positioning cylinder exceeds a safety threshold; an electronic control system operatively connected to said pressure sensor and said first control valve, wherein said electronic control system outputs said first control signal to said first control valve to change said first control valve from said first state to said second state only after said electrical pressure signal output by said pressure sensor to said electronic control system indicates that said safety threshold is satisfied.