omitted herein and a moving speed regulator 10 for a hydraulically driven work implement which differs from those of the prior art system will be described below giving priority to it in fig2 a pilot fluid under pressure is supplied by a pilot pump p through a lifting pilot valve i 1 into a pilot fluid conduit j 1 so as to control a lifting control valve g further there is provided a circuit 13 extending from this pilot fluid conduit j 1 through a change over valve 11 to a pressure regulating valve 12 the fluid pressure in the bottom ends of lifting cylinders b 1 and b 2 is introduced through a pilot piping 14 into the change over valve 11 the arrangement is made such that the change over valve 11 is changed over to its blocked or closed position 11 1 when the fluid pressure in the bottom ends of the lifting cylinders b 1 and b 2 which is a pressure required to lift a boom 34 a 34 in fig2 d is less than a preset pressure which is referred to as p 1 below whilst the pressure in the bottom ends of the lifting cylinders b 1 b 2 is more than the pressure p 1 preset.