Abstract: The present invention includes:a hydraulic pump 10 that is driven by a driving motor; a travel motion motor 12 that is driven with pressure oil supplied from the hydraulic pump 10; a travel motion control valve 11 that controls a flow rate of the pressure oil supplied from the hydraulic pump 10 to the travel motion motor 12; a means for operation 22a with which the travel motion control valve 11 is operated; a means for rotation rate detection 95 that detects a rotation rate N of the travel motion motor 12; and a means for motor over rotation prevention 14, 17, 32 that reduces the rotation rate of the travel motion motor 12 if the means for rotation rate detection 95 detects a rotation rate equal to or higher than a predetermined rotation rate upper limit Nmax.

Abstract: A work machine is provided having a starter motor for starting a prime mover, which without provision of any special hydraulic equipment, allows for draining pressure oil that still remains in a hydraulic actuator for driving a front attachment. The work machine is provided with a boom cylinder for driving a front attachment, a flow rate control valve for controlling a flow of pressure oil to be supplied to the boom cylinder, and a pilot valve for producing an output of a pilot control signal, which serves to switch the flow rate control valve, by using, as a primary pressure, pressure oil delivered from a pilot hydraulic pump driven by an engine. A fuel stop switch is provided for performing stop control on a supply of fuel, which drives the engine, and a switch is provided for maintaining drivable a starter motor, which starts the engine, responsive to the stop control of the supply of fuel to the engine by the fuel stop switch.

Abstract: A prime mover control device of a construction machine according to the present invention includes a hydraulic pump (11) driven by a prime mover (40), a hydraulic traveling motor (5) driven with pressure oil output from the hydraulic pump (11), and a control valve (12) that controls a flow of the pressure oil from the hydraulic pump (11) to the hydraulic motor (5) in response to an operation of an operating member (22a).

Abstract: A hydraulic circuit includes a control valve that controls flow of pressure oil from a hydraulic source to work hydraulic cylinders, an operating device that issues a command for drive of the control valve, valve devices each comprising a check valve, each provided in correspondence to one of the plurality of work hydraulic cylinders to allow and prohibit outflow of pressure oil from a work hydraulic cylinder, a commanding device that outputs a command allowing or a command prohibiting extension/contraction for each of the work hydraulic cylinders and a control device that controls each of the valve devices to allow outflow of pressure oil from the work hydraulic cylinder by invalidating a check valve function in response to the command for allowing extension/contraction and to prohibit outflow of pressure oil from the work hydraulic cylinder with the check valve in response to the command for prohibiting extension/contraction.

Abstract: The present invention includes an undercarriage (1), a revolving superstructure (2) rotatably mounted atop the undercarriage (1), a hydraulic source (21, 28) disposed at the revolving superstructure (2), at least a plurality of work hydraulic cylinders (11) disposed at the undercarriage (1), that are to be driven by pressure oil from the hydraulic source (28), a control valve (22) that controls flow of pressure oil from the hydraulic source (28) to the work hydraulic cylinders (11), an operating means (26) for issuing a command for drive of the control valve (22), valve devices (12a, 12b) each comprising a check valve, each provided in correspondence to one of the plurality of work hydraulic cylinders (11) to allow and prohibit outflow of pressure oil from a work hydraulic cylinder (11), a commanding means (41, 42) for outputting one of a command for allowing extension/contraction and a command for prohibiting extension/contraction for each of the work hydraulic cylinders (11) and a control means (34 to 36, 4

Abstract: A prime mover control device of a construction machine includes a hydraulic pump (24) driven by a prime mover (10), an actuator (5) driven with pressure oil discharged from the hydraulic pump (24), and a control valve (25) that controls a flow of the pressure oil from the hydraulic pump (24) to the actuator (5) in response to an operation of a first operating member (22a).

Abstract: The present invention includes a hydraulic source (28), at least a plurality of work hydraulic cylinders (11) of a single type, that are to be driven with pressure oil from the hydraulic source (28), a control valve (22) that controls a flow of pressure oil from the hydraulic source (28) to the work hydraulic cylinders (11), an operating means for (26) issuing a command for drive of the control valve (22), a selector switch (41, 42) that selects at least an independent operation of the work hydraulic cylinders (11), and a pressure oil control means (12a, 12b, 34 to 37) for allowing the pressure oil to flow to a work hydraulic cylinder (11) selected with the selector switch (41, 42) and disallowing flow of pressure oil to other work hydraulic cylinders (11).

Abstract: A prime mover control device of a construction machine according to the present invention includes a hydraulic pump (11) driven by a prime mover (40), a hydraulic traveling motor (5) driven with pressure oil output from the hydraulic pump (11), and a control valve (12) that controls a flow of the pressure oil from the hydraulic pump (11) to the hydraulic motor (5) in response to an operation of an operating member (22a).

Abstract: The present invention includes a hydraulic pump (11), a variable displacement hydraulic motor (5) for traveling driven by pressure oil from the hydraulic pump (11), a motor displacement control means (17, 18) for adjusting a displacement of the hydraulic motor (5) in correspondence to a drive pressure at the hydraulic motor (5), an operating member (22) through which a forward travel command and a backward travel command for the vehicle are issued, a control means (12) to be driven in response to an operation of the operating member (22), for controlling a flow of pressure oil from the hydraulic pump (11) to the hydraulic motor (5), a reverse operation detection means (41A, 41B) for detecting a reverse operation of the operating member (22) performed to a reverse side opposite from a direction along which the vehicle is advancing, and a cavitation preventing means (25A,25B) engaged in operation so as to prevent occurrence of cavitation at the hydraulic motor (5) when the reverse operation at the operating mem

Abstract: A control apparatus of a construction machine according to the present invention includes a variable displacement hydraulic pump (10) driven by a prime mover (20), a hydraulic actuator (5) driven with pressure oil discharged from the hydraulic pump (10), and a rotation speed detection means (31) for detecting an actual rotation speed (Nr) of the prime mover (20).

Abstract: A construction machine according to the present invention includes a variable displacement hydraulic pump (11, 12) driven by a prime mover (10), a single traveling actuator (5) driven with pressure oil discharged from the hydraulic pump (11), a plurality of work actuators (2a, 4d to 4f) driven with the pressure oil discharged from the hydraulic pump (11, 12), a plurality of control valves (13 to 17) that control flows of the pressure oil from the hydraulic pump (11) to each of the traveling actuator (5) and the plurality of work actuators (2a, 4d to 4f), a detection means (24) for detecting a drive command for the traveling actuator (5), and a flow rate control means (11a, 30, 40, 43) for increasing a maximum flow rate of the hydraulic pump (11) when the drive command for the traveling actuator (5) is detected with the detection means (24).

Abstract: The present invention includes: a hydraulic pump 10 that is driven by a driving motor; a travel motion motor 12 that is driven with pressure oil supplied from the hydraulic pump 10; a travel motion control valve 11 that controls a flow rate of the pressure oil supplied from the hydraulic pump 10 to the travel motion motor 12; a means for operation 22a with which the travel motion control valve 11 is operated; a means for rotation rate detection 95 that detects a rotation rate N of the travel motion motor 12; and a means for motor over rotation prevention 14, 17, 32 that reduces the rotation rate of the travel motion motor 12 if the means for rotation rate detection 95 detects a rotation rate equal to or higher than a predetermined rotation rate upper limit Nmax.