A hydraulic fluid energy regeneration apparatus of a work machine includes: a regeneration hydraulic motor driven by a return hydraulic fluid; a first hydraulic pump mechanically connected to the regeneration hydraulic motor; a second hydraulic pump that delivers a hydraulic fluid for driving a hydraulic actuator; a confluence line that causes the hydraulic fluid delivered from the first hydraulic pump to join the hydraulic fluid delivered from the second hydraulic pump; a first adjuster configured to adjust the flow rate of the hydraulic fluid of the first hydraulic pump; and a second adjuster configured to adjust the delivery flow rate of the second hydraulic pump. A control device includes: a first calculation section configured to calculate a non-confluence time pump flow rate in the case where the hydraulic actuator is driven solely by the second hydraulic pump and calculate a control command output to the first adjuster such that the flow rate of the hydraulic fluid from the first hydraulic pump is equal to or lower than the non-confluence time pump flow rate; and a second calculation section configured to calculate a target pump flow rate by subtracting from the non-confluence time pump flow rate the flow rate of the hydraulic fluid from the first hydraulic pump and calculate a control command output to the second adjuster such that the target pump flow rate is attained.

Provided is a work machine capable of regenerating a return hydraulic fluid from a hydraulic actuator while preventing a drag loss of a regeneration hydraulic motor and a hydraulic pump from increasing and preventing the regeneration efficiency of the regeneration hydraulic motor from decreasing. A controller 100 computes a required regeneration hydraulic motor revolution speed from a displacement of a regeneration hydraulic motor 13 and a regeneration flow rate of the regeneration hydraulic motor, computes a required first hydraulic pump revolution speed from a displacement of a first hydraulic pump 15 and a target assist flow rate of the first hydraulic pump, and selects a greater one of the required regeneration hydraulic motor revolution speed and the required first hydraulic pump revolution speed as a target revolution speed of an electric motor 14.

A work machine measurement system includes an image acquisition unit that acquires an image of a work target captured, while a swinging body of a work machine is swinging, by an image capturing device mounted on the swinging body, a three-dimensional position calculation unit that calculates a three-dimensional position of the work target based on the image, a swing data acquisition unit that acquires swing data about the swinging body, a determination unit that determines whether or not the swing data satisfies a predefined swinging condition and an output unit that outputs a swinging instruction signal based on a result of the determination by the determination unit.

A working machine includes a prime mover, a hydraulic pump to be driven by power of the prime mover and to output operation fluid, a hydraulic actuator to be operated by the operation fluid, and a control device. The control device has a revolving-speed controller to increase and decrease a revolving speed of the prime mover, a first setting portion to set a limit value of the revolving speed of the prime mover, and a revolving-speed limiter to limit the revolving speed of the prime mover set by the revolving-speed controller to the limit value set by the first setting portion.

A hydraulic system for a working machine, includes an operation member, an operation valve to change an output pressure of an operation fluid in accordance with operation of the operation member, a hydraulic device to be activated by the operation fluid outputted from the operation valve, a first fluid tube coupling the operation valve to the hydraulic device, and a bleed circuit connected to the first fluid tube and configured to output the operation fluid in the first fluid tube. The first fluid tube includes a first section fluid tube arranged in a section between the operation valve and a coupling portion coupling the first fluid tube to the bleed circuit, and a second section fluid tube arranged in a section between the coupling portion and the hydraulic device, the second section fluid tube having an inner diameter different from an inner diameter of the first section fluid tube.

A controller (18) calculates, based on a target loading weight (P) that is a target value of a total weight of working objects to be loaded into a hauling vehicle, a set loading time number indicative of a loading time number required for the construction machine before the target loading weight (P) is reached and bucket shape information indicative of a shape of a bucket (7), an appropriate loading weight (W.sub.a) that is an appropriate value of the weight of the working objects to be loaded into the hauling vehicle by a single time loading work by the construction machine, creates an appropriate amount illustration (30) that is an illustration of a state at which the working objects of the appropriate loading weight (W.sub.a) are loaded into the bucket and that illustrates the state of the working objects, based on the appropriate loading weight (W.sub.a) and the bucket shape information, and controls a display device (19) to display an illustration (29) of the bucket (7) and the appropriate amount illustration (30) in a superimposed relationship.

A hydraulic system for a working machine is a load sensing system and includes a hydraulic actuator for movement of an implement and a control valve having an inlet valve and an outlet valve for controlling the flow of hydraulic fluid from a pump to the hydraulic actuator and for draining hydraulic fluid from the hydraulic actuator, respectively. The hydraulic system also includes an arrangement for determining the load on the hydraulic actuator. The hydraulic system further includes a valve for disconnecting the flow of hydraulic fluid from the pump to the hydraulic actuator, while allowing another flow of hydraulic fluid to the hydraulic actuator, provided that the determined load on the hydraulic actuator exceeds a threshold value.

A construction machine includes a hydraulic cylinder configured to drive an attachment, a hydraulic circuit configured to supply hydraulic oil to the hydraulic cylinder, an input device that is operated by an operator, and a controller configured to control the hydraulic circuit in at least one of a first control mode where the attachment is caused to generate a force corresponding to an operation amount of the input device and a second control mode where the attachment is driven at a velocity corresponding to the operation amount of the input device.

A work machine management apparatus includes: a working element identification information acquiring unit acquiring working element identification information indicating replacement of a working element; a flow rate setpoint acquiring unit acquiring a flow rate setpoint of a hydraulic oil for the working element; a pressure setpoint acquiring unit acquiring a pressure setpoint of the hydraulic oil for the working element; a working element operation information acquiring unit acquiring the acquired flow rate setpoint, the acquired pressure setpoint and operation information of the working element; and a working element actual operation information calculator calculating actual operation information containing an actual operation duration of the working element based on the information acquired by each of the working element identification information acquiring unit, the flow rate setpoint acquiring unit, the pressure setpoint acquiring unit and the working element operation information acquiring unit.

A work machine includes: control valves that control flows of a hydraulic operating oil supplied to actuators; operation lever devices that generate hydraulic signals to be output to the corresponding control valves according to an operation; solenoid proportional valves that reduce pressure of the hydraulic signals generated by the corresponding operation lever devices; and a front implement control section that controls the solenoid proportional valves. The work machine further includes: operation signal lines connected to the operation lever devices; signal input lines connected to the control valves; pressure reducing lines provided with the solenoid proportional valves; and selector valves that have a first position that interrupts connection of the operation signal lines and the pressure reducing lines and directly connects the operation signal lines to the signal input lines, and a second position that connects the operation signal lines to the signal input lines via the pressure reducing lines.