Abstract: A hydraulic control device for a work vehicle includes: a hydraulic pump that supplies pressure oil; an arm drive actuator that drives, with pressure oil supplied from the hydraulic pump, an arm attached to the work vehicle so as to swing the arm; a bucket drive actuator that drives, with pressure oil supplied from the hydraulic pump, a bucket attached to a front end of the arm, so as to swing the bucket; an arm drive pressure oil control valve that controls drive of the arm drive actuator by controlling pressure oil supplied from the hydraulic pump to the arm drive actuator; a bucket drive pressure oil control valve that controls drive of the bucket drive actuator by controlling pressure oil supplied from the hydraulic pump to the bucket drive actuator; an arm operation unit that controls the arm drive pressure oil control valve; a bucket operation unit that controls the bucket drive pressure oil control valve; an operating state detection unit that detects operating states of the arm drive actuator and the

Abstract: An inlet port (17A) of a first exhaust gas purifying device (16) is provided on a side opposite to an engine (8) by sandwiching an axis (O1-O1) of a cylindrical body (17) of the first exhaust gas purifying device (16). An exhaust pipe (26) connecting the engine (8) and the first exhaust gas purifying device (16) is constituted by a lateral pipe line (27) extending in a left and right direction of an upper revolving structure (3) on a front side of the first exhaust gas purifying device (16) and having a bellows pipe (28) in the middle for absorbing relative displacement between the engine (8) and the first exhaust gas purifying device (16) and a bent pipe line (29) bent having a U-shape rearward from a tip end side of the lateral pipe line (27) and connected to the inlet port (17A) of the first exhaust gas purifying device (16).

Abstract: To provide a construct ion machine in which the temperature of a battery and aqueous urea within an aqueous urea tank can be prevented from rising and high stability can be secured in the vehicle body.

Abstract: A structure for mounting a cooling fan (30) includes a spider (31) and blades (32) at free ends of mounting arms (31c) of the spider (31). A rotation center portion (31b) of the spider (31) is mounted on a rotating shaft (33) through a fan adaptor (60), the rotating shaft (33) being driven by an engine (27). A partition member (70) for closing gaps in the spider (31) is mounted on the fan adaptor (60). As a result of this configuration, the gaps between the mounting arms (31c) of the spider (31) can be reliably closed, and therefore the backflow of air from the downstream side (high pressure side) of the cooling fan (30) to the upstream side (low pressure side) thereof can be prevented.

Abstract: On the right front side of a revolving frame (5) constituting an upper revolving structure (3), an operating oil tank (11) and a fuel tank (12) are arranged. On the front side of this operating oil tank (11) and the fuel tank (12), an equipment accommodating case (13) forming an accommodating space (13A) inside is provided. In the accommodating space (13A) in the equipment accommodating case (13), a control valve unit (20) for controlling supply/discharge of the operating oil and a urea water tank (24) storing urea water for removing nitrogen oxides contained in an exhaust gas of the engine (8) are arranged together.

Abstract: On a rear part side of a revolving frame (5) constituting an upper revolving structure (3), a counterweight (7) holding weight balance with a working mechanism (4) is provided, and on the front side of the counterweight (7), an engine (9) and an exhaust gas post-treatment device (21) for applying purification treatment to an exhaust gas of the engine (9) are provided. The exhaust gas post-treatment device (21) is configured by connecting a PM trapping filter device (22) and an NOx purifying device (23), and the PM trapping filter device (22) is mounted on the engine (9), while the NOx purifying device (23) is mounted on the counterweight (7). When the counterweight (7) is to be removed from the revolving frame (5), the NOx purifying device (23) is supported by a treatment device support bracket (26) mounted on the engine (9). As a result, the counterweight (7) can be removed while the PM trapping filter device (22) and the NOx purifying device (23) are connected.

Abstract: A first accommodating case (13) which is located more forward than a fuel tank (12) and is small in height dimension (H1) of an upper surface (13E) is provided on the right side of a revolving frame (5). A second accommodating case (16) the position of an upper surface (16E) of which is higher than the upper surface (13E) of the first accommodating case (13) and is lower than an upper surface plate (12E) of the fuel tank (12) is provided on the rear side of the upper surface (13E) of this first accommodating case (13). Moreover, a reducing agent tank (20) is provided in a tank accommodating space (15) in the first accommodating case (13) and articles such as a tool box (23) and the like are accommodated in an article accommodating space (17) in the second accommodating case (16).

Abstract: A hydraulic drive device for a construction machine includes an engine stopping unit and a discharge rate control unit. The engine stopping unit stops the engine when a predetermined state of the construction machine has continued for a predetermined period of time. The discharge rate control unit controls a discharge rate control pressure being input to the regulator, when an exhaust emission control device performs regeneration control, or performs warm-up control, and the gate lock lever is in the open position.

Abstract: A hydraulic drive device for a hydraulic excavator, includes: a first hydraulic pump; a first boom directional control valve and a second arm directional control valve which are connected in parallel to the first pump; a second hydraulic pump; and a second boom directional control valve and a first arm directional control valve which are connected in parallel to the second pump; wherein: the hydraulic drive device also includes: a third hydraulic pump; a third boom directional control valve connected to the third pump and controlling the flow of pressure oil supplied to a boom cylinder; and a third arm directional control valve connected in tandem with the third boom directional control valve and controlling the flow of pressure oil supplied to an arm cylinder.

Abstract: On the right front side of a revolving frame (5) constituting an upper revolving structure (3), an operating oil tank (11) and a fuel tank (12) are arranged. On the front side of this operating oil tank (11) and the fuel tank (12), an equipment accommodating case (13) forming an accommodating space (13A) inside is provided. In the accommodating space (13A) in the equipment accommodating case (13), a control valve unit (20) for controlling supply/discharge of the operating oil and a urea water tank (24) storing urea water for removing nitrogen oxides contained in an exhaust gas of the engine (8) are arranged together.

Abstract: On a rear part side of a revolving frame (5) constituting an upper revolving structure (3), a counterweight (7) holding weight balance with a working mechanism (4) is provided, and on the front side of the counterweight (7), an engine (9) and an exhaust gas post-treatment device (21) for applying purification treatment to an exhaust gas of the engine (9) are provided. The exhaust gas post-treatment device (21) is configured by connecting a PM trapping filter device (22) and an NOx purifying device (23), and the PM trapping filter device (22) is mounted on the engine (9), while the NOx purifying device (23) is mounted on the counterweight (7). When the counterweight (7) is to be removed from the revolving frame (5), the NOx purifying device (23) is supported by a treatment device support bracket (26) mounted on the engine (9). As a result, the counterweight (7) can be removed while the PM trapping filter device (22) and the NOx purifying device (23) are connected.

Abstract: On an upper revolving structure, an engine having an exhaust port is mounted. In the midway portion of the exhaust pipe connecting the exhaust port of the engine and an exhaust gas post-treatment device, a first bellows pipe and a second bellows pipe are arranged through a connecting pipe having an L-shaped bending portion. In this case, the first bellows pipe and the second bellows pipe are arranged so as to have a positional relationship in which axis lines thereof (X1-X1, Z1-Z1) cross each other. That is, the first bellows pipe is arranged in a horizontal direction so that its axis line (X1-X1) extends in the left-right direction of the upper revolving structure. The second bellows pipe is arranged so that its axis line (Z1-Z1) matches the vertical direction of the upper revolving structure.

Abstract: A prime mover revolution speed control system for a hydraulic construction machine sets the revolution speed of the prime mover in accordance with the operating state invoked by an operating command and as a result of a determination of an excavation state so that that the revolution speed of the engine can be increased for a heavy load (speedup) in the excavation state. When the control lever is fully operated in the direction of arm crowding, the control lever 43 is also operated, and first judgment conditions are all met to conclude that an excavation state has begun. During excavation work, when the control lever 44 is subjected to a half or greater operation in the arm crowding direction, second judgment conditions are all met to conclude that the excavation state persists, and the speedup sequence is continued.

Abstract: To provide a construct ion machine in which the temperature of a battery and aqueous urea within an aqueous urea tank can be prevented from rising and high stability can be secured in the vehicle body.

Abstract: An aqueous urea tank structure is provided for a construction machine, in which a temperature rise of the aqueous urea within the tank can be suppressed and the load applied to the tank due to vibration of a vehicle body can be reduced. The aqueous urea tank structure including an aqueous urea tank which is disposed within a revolving upperstructure of a hydraulic excavator to store aqueous urea that purifies the exhaust gas discharged from an engine, wherein the aqueous urea tank structure further includes a securing member which encloses the periphery of the aqueous urea tank to secure the aqueous urea tank within the revolving upperstructure, and heat insulating materials which are interposed between the securing member and the aqueous urea tank to hold the aqueous urea tank. The securing member contains a box.

Abstract: A relief pressure control system is provided with a controller for outputting, responsive to an adjustment signal output from a dial switch, a control signal to control a relief pressure of a variable solenoid relief valve, a display unit for displaying, responsive to display signals outputted from the controller, a relationship between a circuit pressure output from a pressure sensor and a pressure required by a hydraulic cylinder, and a control device constituting a start instruction unit for instructing a start of control of the variable solenoid relief valve. Stop valves are arranged in sections of main lines, which communicate a directional control valve and the hydraulic cylinder with each other, to open or close the section. The sections are located between positions on the main lines, where the variable solenoid relief valves are connected to the main lines, respectively, and the hydraulic cylinder.

Abstract: Disclosed is a hydraulic drive system for a working machine, which enables to conduct forced regeneration continuously for a sufficient time. Based on an input of a lock detection signal S1 from a gate lock detection switch 40, a controller 50 detects that a gate lock lever 32 for controlling a gate lock on/off valve 33 is in a locked state, in other words, hydraulic actuators such as an arm cylinder 12 arranged on a hydraulic excavator 1 are all in non-operated states. Upon an input of a forced regeneration command signal So from a forced regeneration switch 53 in this detected state, control signals Cp,Cf are outputted to a boosting control valve 51 and regulator 52 to make a forced regeneration means (an arm cylinder control valve 27 and the regulator 52) conduct forced regeneration.

Abstract: A hydraulic control device for a work vehicle includes: a hydraulic pump that supplies pressure oil; an arm drive actuator that drives, with pressure oil supplied from the hydraulic pump, an arm attached to the work vehicle so as to swing the arm; a bucket drive actuator that drives, with pressure oil supplied from the hydraulic pump, a bucket attached to a front end of the arm, so as to swing the bucket; an arm drive pressure oil control valve that controls drive of the arm drive actuator by controlling pressure oil supplied from the hydraulic pump to the arm drive actuator; a bucket drive pressure oil control valve that controls drive of the bucket drive actuator by controlling pressure oil supplied from the hydraulic pump to the bucket drive actuator; an arm operation unit that controls the arm drive pressure oil control valve; a bucket operation unit that controls the bucket drive pressure oil control valve; an operating state detection unit that detects operating states of the arm drive actuator and the

Abstract: In an attachment control apparatus for a hydraulic excavator having a hydraulic circuit that includes a hydraulic pump, a plurality of actuators having a breaker which is an attachment actuator, and a plurality of flow control valves having an attachment flow control valve that is switched by operation pilot pressure from a control pedal device to supply delivery fluid of the hydraulic pump to the attachment actuator, if the control pedal device is operated in a state where an attachment mode is not selected by an attachment selection device, the movement of the attachment actuator is limited. Thus, failure and reduced life of the attachment and other hydraulic devices can be prevented in the event that an operator has forgotten to switch from a normal mode to an attachment mode and has operated the attachment.

Abstract: A first hydraulic circuit leads, as clutch control pressure, pressurized oil supplied from a first hydraulic pump, to a transmission control device after regulating the pressurized oil, and leads, as torque converter operation oil, pressured oil to a torque converter, and leads pressurized oil to an oil cooler. Through a second hydraulic circuit, pressurized oil from a second hydraulic pump is distributed to a circuit portion downstream of the pressure regulation valve and upstream of a safety valve and to a circuit portion downstream of the torque converter and upstream of the oil cooler. A flow control device changes a proportion of a rate of flow in the second hydraulic circuit so that a proportion of the rate of flow to the circuit portion downstream of the torque converter and upstream of the oil cooler increases as pressure at an entrance of the torque converter increases.