Abstract: A drive control system for a work machine. A gradual stoppage command and an operation speed limitation command are calculated and output. A pilot pressure is corrected such that, upon a stoppage operation of a control lever, a drive actuator is stopped gradually; and the pilot pressure is corrected such that an operation speed of the drive actuator is limited. A supply of the pilot hydraulic fluid to the speed increasing unit is interrupted when a failure of a speed increasing solenoid proportional valve of the speed increasing unit is detected.

Abstract: The work machine includes a stabilization control calculation unit that calculates and outputs a gradual stoppage command for making a drive actuator stop gradually and an operation speed limitation command for limiting an upper limit operation speed according to the status of stability of the work machine, a stoppage characteristic modification unit that corrects pilot pressure so as to make the drive actuator stop gradually when a stoppage operation is performed on a control lever, and an operation speed limitation unit that corrects the pilot pressure so as to limit the operation speed of the drive actuator.

Abstract: A drive control system for a work machine includes: a stabilization control calculation unit (60a) that calculates and outputs a gradual stoppage command and an operation speed limitation command; a stoppage characteristic modification unit (210) that includes a speed increasing unit and corrects a pilot pressure such that, upon a stoppage operation of a control lever, a drive actuator is stopped gradually; an operation speed limitation unit (240) that includes a speed reducing unit and corrects the pilot pressure such that an operation speed of the drive actuator is limited; and a speed increase interruption unit (330) that interrupts, when a failure of a speed increasing solenoid proportional valve of the speed increasing unit is detected, supply of the pilot hydraulic fluid to the speed increasing unit.

Abstract: The work machine includes a stabilization control calculation unit that calculates and outputs a gradual stoppage command for making a drive actuator stop gradually and an operation speed limitation command for limiting an upper limit operation speed according to the status of stability of the work machine, a stoppage characteristic modification unit that corrects pilot pressure so as to make the drive actuator stop gradually when a stoppage operation is performed on a control lever, and an operation speed limitation unit that corrects the pilot pressure so as to limit the operation speed of the drive actuator.

Abstract: A hydraulic circuit system for a hydraulic excavator, which has a hydraulic circuit for an attachment, includes: a directional control valve 16 that supplies a hydraulic fluid to an attachment connected to the hydraulic circuit for an attachment; a first over-load relief valve unit 38 that is provided in one of lines of the hydraulic circuit for an attachment; a second over-load relief valve unit 39 that is provided in the other of the lines of the hydraulic circuit for an attachment; a first proportional solenoid valve 40 that controls set relief pressure of the first over-load relief valve unit 38; and a second proportional solenoid valve 41 that controls set relief pressure of the second over-load relief valve unit 39. The attachment having various characteristics and capacity, such as a hydraulic breaker or a crusher, can be applied to the hydraulic circuit for an attachment in a simple configuration.

Abstract: A hydraulic circuit system for a hydraulic excavator, which has a hydraulic circuit for an attachment, includes: a directional control valve 16 that supplies a hydraulic fluid to an attachment connected to the hydraulic circuit for an attachment; a first over-load relief valve unit 38 that is provided in one of lines of the hydraulic circuit for an attachment; a second over-load relief valve unit 39 that is provided in the other of the lines of the hydraulic circuit for an attachment; a first proportional solenoid valve 40 that controls set relief pressure of the first over-load relief valve unit 38; and a second proportional solenoid valve 41 that controls set relief pressure of the second over-load relief valve unit 39. The attachment having various characteristics and capacity, such as a hydraulic breaker or a crusher, can be applied to the hydraulic circuit for an attachment in a simple configuration.