Hydraulic control for a quick coupler

A hydraulic control adapted for use with a coupling for attaching an implement to a machine, the hydraulic control comprising:

• a hydraulic actuator having a head end and a rod end, the rod end includes a piston rod engageable with the implement to couple the implement to the machine;
• a first system of pressurized fluid being connected to the head end of the actuator for providing a constant fluid pressure to the head end of the actuator for engaging and maintaining the piston in engagement with the implement the first system includes a first pump providing a first predetermined fluid pressure to the head end of the hydraulic actuator;
• a second system of pressurized fluid selectively connected to the rod end of the actuator for disengaging the piston rod from the implement the second system includes a second pump providing a second predetermined fluid pressure to the rod end of the hydraulic actuator, the second predetermined fluid pressure being greater than the first predetermined fluid pressure;
• a check valve being actuated by a pilot signal from the second system of pressurized fluid;
• and
• a thermal check valve having one side connected between the first pump and the pilot actuated check valve and a second end connected between the pilot actuated check valve and the head end of the hydraulic actuator.