Abstract: A rotational speed pickup 71 (traveling speed detection means), a hydraulic pressure sensor 72 (traveling operation detection means), a hydraulic pressure sensor 73 (drive status detection means), and a voltage sensor 74 (transmission shift position detection means) detect parameters regarding the traveling state of a hydraulic traveling vehicle. A control unit 80, a solenoid proportional valve 81, an engine control system 82, and a motor regulator 33 determine the operating state of the hydraulic traveling vehicle based on the parameters regarding the traveling state, and control the equivalent displacement of the traveling system including a hydraulic traveling motor 14 and the maximum flow rate supplied to the hydraulic traveling motor 14 according to the result of determination. The pump flow rate and motor displacement are controlled according to the traveling state in this way, thereby ensuring favorable traveling performance without degrading the fuel efficiency.

Abstract: An operation circuit for a work vehicle drives an electromagnetic actuator by generating an operation signal corresponding to a switch operation and drives a work actuator in response to the drive of the electromagnetic actuator. By installing a specific detachable electric circuit unit in a first operation circuit that generates a first operation signal in response to an operation of a specific switch, the first operation circuit can be modified to a second operation circuit that generates a second operation signal different from the first operation signal in response to an operation of the same switch.

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: The present invention includes a hydraulic brake device 4, 5 that generates a braking force corresponding to an operation of a brake pedal 1 performed while the vehicle is traveling, a brake lock means 6 for applying a hydraulic lock on the hydraulic brake device 4, 5 and releasing the hydraulic lock, a brake pedal operation detection means 22 for detecting an operation of the brake pedal 1, and a control means 10 for controlling the brake lock means 6 so as to apply the hydraulic lock on the hydraulic brake device 4, 5 upon detecting via the brake pedal operation detection means 22 a predetermined depressing operation of the brake pedal 1.

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: An engine control device for a work vehicle includes: a hydraulic pump 2 driven by an engine 1; a hydraulic actuator 5 driven with pressure oil supplied from the hydraulic pump 2; a drive disallowing means 3 for disallowing drive of the hydraulic actuator with the pressure oil supplied from the hydraulic pump 2; a disallowed drive detection means 14 for detecting whether or not the drive disallowing means 3 is disallowing the drive; and a rotation rate control means 12-16 for executing control so as to adjust an engine speed to a low rotation rate NS, lower than a minimum rotation rate (hereafter referred to as a low idle rotation rate NL) at which the hydraulic actuator 5 can still be driven, at least when the disallowed drive detection means 14 detects that the drive disallowing means 3 is disallowing the drive.

Abstract: The present invention includes a hydraulic pump 10 driven by a prime mover 1, a traveling motor 12 driven with pressure oil delivered from the hydraulic pump 10, a control valve 11 for traveling that controls a flow rate of the pressure oil delivered from the hydraulic pump 10 to the traveling motor 12, a counterbalance valve 13 switched in response to a motor load pressure supplied via the control valve 11, that generates a braking pressure at a conduit L1A or L1B disposed on a return side of the traveling motor 12 as the load pressure becomes lower, an overspeed detection means 42 for detecting an overspeed state in the traveling motor 12, and a motor overspeed inhibiting means 50 for inhibiting rotation of the traveling motor 12 if the overspeed detection means 42 detects an overspeed state in the traveling motor 12 until a braking pressure is generated through a switchover at the counterbalance valve 13 and the traveling motor 12 is no longer in the overspeed state.

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 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 10 driven by a prime mover 1, a traveling motor 12 driven with pressure oil delivered from the hydraulic pump 10, a control valve 11 for traveling that controls a flow rate of the pressure oil delivered from the hydraulic pump 10 to the traveling motor 12, a counterbalance valve 13 switched in response to a motor load pressure supplied via the control valve 11, that generates a braking pressure at a conduit L1A or L1B disposed on a return side of the traveling motor 12 as the load pressure becomes lower, an overspeed detection means 42 for detecting an overspeed state in the traveling motor 12, and a motor overspeed inhibiting means 50 for inhibiting rotation of the traveling motor 12 if the overspeed detection means 42 detects an overspeed state in the traveling motor 12 until a braking pressure is generated through a switchover at the counterbalance valve 13 and the traveling motor 12 is no longer in the overspeed state.

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: A failure detection device for a hydraulic motor according to the present invention comprises a hydraulic pump 3 that is driven by a prime mover 2; a hydraulic motor 1 for traveling that is driven by hydraulic oil discharged from the hydraulic pump 3; a transmission 7 that is connected with an output shaft of the hydraulic motor 1 for traveling; a stopping detection device 26 that detects that a traveling vehicle has stopped; a fluid level detection device 35 that detects an oil level in the transmission 7; and a warning device 39, 40 that issues a warning when the stopping detection device 26 detects that the traveling vehicle has stopped, and also the fluid level detection device 35 detects that the oil level in the transmission 7 has reached a predetermined value La.

Abstract: The present invention provides a construction machine adopting a structure that assures a predetermined sound pressure level along a forward direction relative to the construction machine and allows a warning horn to be miniaturized. Warning horns 12 and 13 are mounted in the vicinity of at least either a left headlamp 9 or a right headlamp 10 provided on the left side and the right side of a vehicle body 3 of the construction machine. The warning horns 12 and 13 are housed inside a bracket 11 used to mount the headlamp 9 or 10. The plurality of warning horns 12 and 13 are disposed on a single side toward the left headlamp 9 or the right headlamp 10. Since a front attachment 7 does not block the sound generated from the warning horns 12 and 13 and thus the warning sound can travel without hindrance along the forward direction, a predetermined sound pressure level is achieved with ease along the forward direction relative to the vehicle body 3.

Abstract: The wheeled work vehicle according to the present invention has a link that links at least either one of the axles and provided at the front and the rear of the vehicle to a body, suspension hydraulic cylinders provided at the left side and the right side of the chassis to link the axle to the body in conjunction with the link and an accumulator that is made to communicate with oil chambers and of the hydraulic cylinders via restrictors.

Abstract: A failure detection device for a hydraulic motor of the present invention comprises a hydraulic pump 3 that is driven by a prime mover 2; a hydraulic motor 1 that is driven by hydraulic oil discharged from the hydraulic pump 3; an abnormality detection device 35 that detects an abnormal operation of the hydraulic motor 1; and a warning device 30, 39, 40 that issues a warning when the abnormal operation of the hydraulic motor 1 is detected by the abnormality detection device 35.

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