A compact utility loader compact utility loader comprising a frame, a first track and a second track positioned on either side of the frame, and a pair of loader arms. The loader arms are configured to couple with an attachment via a hitch plate and a hitch pin. The compact utility loader is configured such that as the loader arms are raised and lowered, the hitch pin follows a path approximately defined by a curve ?(x)=4.641e.sup.0.34x. The value x represents a horizontal direction and the function f(x) represents a vertical direction.

A method for estimating a weight of a load in a bucket of a work vehicle includes obtaining, via a controller, a speed of an actuator of a lift coupled to the bucket. The method also includes comparing, via the controller, the speed provided to an instantaneous command to a hydraulic valve coupled to the actuator. The method further includes estimating, via the controller, a hydraulic pressure drop across the hydraulic valve based on the comparison of the speed to the instantaneous command to estimate pressures in the cylinder. The method even further includes determining, via the controller, a hydraulic force of the actuator. The method still further includes estimating, via the controller, the weight of the load in the bucket of the work vehicle based on the estimated pressures in the actuator and the hydraulic force.

A work machine includes: a satellite communication antenna for detecting a position of an upper swing structure; angle sensors detecting postures of two work devices; position computing devices that calculate postures/positions of the two work devices on the basis of outputs from the satellite communication antenna and the angle sensors; a display device on which the position of at least one work device of the two work devices and a position of a target surface are displayed; a display selection switch that outputs a first input signal for displaying a work device selected by an operator from between the two work devices on the display device; and a display changeover section that displays the work device corresponding to the first input signal input from the display selection switch out of the two work devices and the position of the target work object of the work device on the display device.

A hydraulic system for a work machine includes a first switch valve and a first return circuit. The first switch valve is switchable between a confluent position and an isolation position. The first switch valve is switched to the confluent position such that a first operation fluid tube is connected to a second operation fluid tube and a first transmission fluid tube is connected to a second transmission fluid tube. The first switch valve is switched to the isolation position such that the first operation fluid tube is disconnected from the second operation fluid tube and the first operation fluid tube is disconnected from the second operation fluid tube.

The present disclosure relates to a safety system for a construction machine, and the safety system for a construction machine according to the exemplary embodiment of the present disclosure includes: a pilot pump which supplies a pilot working fluid; multiple spools which are operated by the pilot working fluid to control a supply of a main working fluid and each have a signal unit formed in one region thereof; a signal line which sequentially connects the pilot pump and the signal units of the multiple spools and discharges the pilot working fluid, which is supplied by the pilot pump, to a hydraulic tank; and a pressure sensor which measures pressure in the signal line.

A hydraulic excavator (1) includes a controller (40) for generating, when the tip of a work implement (1A) is approaching a target surface (60) due to the pilot pressure output from an operating device (45a, 45b, 46a), a control signal for a boom cylinder (5) such that the tip of the work implement moves along the target surface and controlling the work implement (1A) by outputting the generated control signal to the flow control valve (15a) of the boom cylinder (5). The controller calculates the positional information of a finished shape (97) formed by the work implement, based on the topographic information input from a topographic measurement device (96) that measures the topography near the work machine and corrects the control signal based on the positional information of the finished shape such that the finished shape gets closer to the target surface.

To prevent increase/decrease in pump flow rate due to load variation with change in the posture of a work attachment and improve the operability in arm pushing operation. A hydraulic excavator 1 with a front mechanism including an arm 33 driven by a hydraulic actuator 43 through operation of an operating lever 50 includes: first and second angle sensors 37 and 38 which detect the posture of the arm 33; and a controller 49 which, when the posture of the arm 33 is at a remoter side from an upperstructure 20 than a preset position and the position of a bucket 35 is adjusted from a maximum or nearly maximum preset operation amount of the operating lever 50 in arm pushing operation by the operating lever 50, changes the flow rate characteristic of pressure oil in relation to discharge pressure of a hydraulic pump 41 for supplying pressure oil to the hydraulic actuator 43, to characteristic PTS with a higher flow rate than flow rate characteristic PT at the time of operation with an operation amount other than the above operation amount, to drive the hydraulic pump 41.

There is provided a hydraulic driving device for working machine having operability handling a change in burden weight in a front working device due to a loaded burden and the like when the working machine that accumulates energy in an accumulator and recovers and regenerates the energy performs an operation of lowering the front working device. A hydraulic driving device 5 includes a main pump 101, a boom cylinder 3, a tank 20, a flow rate control valve 6, an accumulator 300, a first differential pressure control valve 201, and a second differential pressure control valve 202. The first differential pressure control valve 201 is located between the boom cylinder 3 and the accumulator 300. The first differential pressure control valve 201 performs control on discharge oil from the boom cylinder 3 such that a differential pressure between before and after the flow rate control valve 6 becomes a target differential pressure. The second differential pressure control valve 202 is located between the accumulator 300 and the tank 20. The second differential pressure control valve 202 performs control on the discharge oil such that a differential pressure between an upstream pressure and a downstream pressure of the flow rate control valve 6 and the first differential pressure control valve 201 becomes the target differential pressure. The first and the second differential pressure control valves 201 and 202 are configured such that the target differential pressure increases according to an increase in pressure of the discharge oil.

An object of the present invention is to provide a hydraulic control system for a work machine that is capable of reducing the loss caused by flow division while reducing a decrease in the speed of a hydraulic actuator due to a combined operation. The hydraulic control system for a work machine includes a first hydraulic actuator, one hydraulic pump, a second hydraulic actuator, and another hydraulic pump. The hydraulic control system further includes operating instruction detection means and pump flow control means. The operating instruction detection means detects that operating instructions are issued to the first hydraulic actuator and the second hydraulic actuator. The pump flow control means individually adjusts the delivery flow rate of the one hydraulic pump and the another hydraulic pump in accordance with operation amounts designated by the operating instructions for the first and second hydraulic actuators. When the first and second hydraulic actuators are simultaneously operated, the pump flow control means increases the delivery flow rate of the one hydraulic pump to a higher rate than when the first hydraulic actuator is operated and the second hydraulic actuator is not operated.

It is an object of the present invention to provide a construction machine capable of efficiently driving a hydraulic cylinder by an accumulator. Thus, the construction machine includes a first control valve disposed in a first hydraulic fluid line connecting a bottom-side fluid chamber of a hydraulic cylinder with an accumulator, and a second control valve disposed in a second hydraulic fluid line connecting a rod-side fluid chamber of the hydraulic cylinder with a tank. The construction machine further includes a third control valve disposed in a third hydraulic fluid line connecting the rod-side fluid chamber with the accumulator, and a fourth control valve disposed in a fourth hydraulic fluid line connecting a line part of the first hydraulic fluid line, which connects the bottom-side fluid chamber with the third control valve, and a line part of the third hydraulic fluid line, which connects the rod-side fluid chamber with the third control valve, with each other.