To perform stable control more quickly after changing the speed of a hoisted load and after starting a winch drum by restricting the hunting of the rotating speed of a hydraulic motor and restricting the deterioration of the fuel economy of a hydraulic working machine.
This control device 1 includes: an inside pilot type counter balance valve 40 provided in a hydraulic motor outlet pipeline 27 for controlling pressure in an outlet of a hydraulic motor 20 so as to become set pressure P1; and a valve control means 50 which controls the inside pilot type counter balance valve 40. In the valve control means 50, motor inlet target pressure Pmi' is set. The valve control means 50 computes the motor holding pressure ΔP of the hydraulic motor 20 when lowering a hoisted load 24 based on a load of the hoisted load 24 which is estimated by a moment limiter 10, and controls the inside pilot type counter balance valve 40 so that the set pressure P1 becomes a total value of the motor inlet target pressure Pmi' and the motor holding pressure ΔP.
IMANISHI ETSUJIRO
SUGANO NAOKI
YAMAGATA KATSUMI
KOBELCO CRANES CO LTD