Moving speed regulator for hydraulically driven work implement

A moving speed regulator for a hydraulically driven work implement comprising a pilot circuit having a pilot pump;

• a hydraulic circuit for driving a work implement, which includes a work implement operating valve adapted to be actuated by a pilot fluid pressure from a hydraulic pilot valve installed in the pilot circuit;
• a pressure regulating valve installed in the pilot circuit so as to regulate the fluid pressure in said pilot circuit;
• and a change-over valve installed in said pilot circuit so as to change over the pressure regulating valve either to its operative condition or to its inoperative condition, the arrangement being made such that the maximum discharge flow rate of the fluid through the work implement operating valve can be controlled by regulating the pressure of the fluid under pressure through the cooperative effect of the change-over valve and the pressure regulating valve, characterized in that said change-over valve is changed over either to its operative condition or to its inoperative condition in response to the fluid pressure in a work implement driving hydraulic cylinder, and when the fluid pressure in the hydraulic cylinder becomes a high pressure more than a predetermined value both the change-over valve and the pressure regulating valve are actuated.