To enable to arbitrarily change a hydraulic pump which supplies pressure oil to a hydraulic actuator at first in a hydraulic control system equipped with the hydraulic actuator using both first and second hydraulic pumps as a pressure oil source. An operation means is installed which can arbitrarily change working order of the first flow rate control valves for boom and stick for controlling the supply flow rate from first hydraulic pump to boom cylinder and stick cylinder and second flow rate control valves for boom and stick for controlling the supply flow rate from second hydraulic pump to boom cylinder and stick cylinder.

To make it possible to control supply, discharge, and recycled flow rates independently of each other for the stick cylinder in a construction machine comprising first and second stick spool valves respectively connected to first and second hydraulic pumps. [Solution] A poppet valve is provided at upstream side of the first stick spool valve for controlling a supply flow rate from first hydraulic pump, the first stick spool valve is configured to supply hydraulic flow from the poppet valve to the stick cylinder without restricting the flow, and when the stick cylinder is extended, the poppet valve is configured to control supply flow rate from the first hydraulic pump to head side oil chamber, the first stick spool valve is configured to control recycled flow rate from a rod side oil chamber to the head side oil chamber, and the second stick spool valve is configured to control the supply flow rate from second hydraulic pump to head side oil chamber and the discharge flow rate from the rod side oil chamber to an oil tank.

A lift device includes a base, a turntable coupled to the base, a boom pivotably coupled to the turntable, and an actuator assembly. The actuator assembly includes a first actuator, a first coupler positioned at a first end of the first actuator, a second actuator, a second coupler positioned at a third end of the second actuator, and a third coupler. The first coupler and the second coupler pivotably couple the first actuator and the second actuator, respectively, to one of the boom or the turntable. The third coupler includes a body and a plurality of arms extending from the body. The body defines (i) a first interface that engages with an opposing second end of the first actuator and (ii) a second interface that engages with an opposing fourth end of the second actuator. The plurality of arms are pivotably coupled to the other one of the boom or the turntable.

A hydraulic system for a working machine includes hydraulic actuators actuated with hydraulic fluid delivered from a hydraulic pump, control valves each of which is shiftable among shift positions to control a flowrate of hydraulic fluid flowing to the corresponding hydraulic actuator, a detection fluid passage, an interlocking control valve, and a pressure detection unit. Each control valve includes an input port, an output port, and a flowrate reduction section. One of the control valves includes a flowrate increase section. The interlocking control valve is configured to be shifted in accordance with a shift of the one of the control valves among the shift positions and to be shifted to a blocking position to block a pilot fluid introduced into the interlocking control valve from the detection fluid passage when the one of the control valves is shifted to the increase position.

The drive unit according to the present disclosure includes two fluid motors serving as drive sources for generating rotational forces, and a channel member having a supply channel for supplying a pressure fluid to the two fluid motors. Each of the two fluid motors includes: a casing having a supply port and a discharge port for the pressure fluid; a drive shaft rotatably supported to the casing; and a motive power generating unit provided in the casing and configured to rotate the drive shaft with the pressure fluid, the pressure fluid being supplied through the supply port and discharged through the discharge port. The two fluid motors are arranged such that the respective drive shafts are disposed parallel to each other and oriented toward opposite sides along rotation axes of the drive shafts. The supply channel supplies the pressure fluid to the supply ports of the two fluid motors.

A working machine includes a machine body, a first hydraulic actuator mounted on the machine body, a first control valve that controls the first hydraulic actuator, a controller that controls the first control valve, and a second hydraulic actuator that is different from the first hydraulic actuator. When the second hydraulic actuator and the first hydraulic actuator are operated in combination, the controller reduces the amount of change in the flow rate of a hydraulic fluid supplied from the first control valve to the first hydraulic actuator with respect to changes in a manipulation amount to operate the first hydraulic actuator to a value smaller than that when the first hydraulic actuator is solely operated.

A work machine comprises: a work implement; a hydraulic cylinder; a hydraulic pump that supplies the hydraulic oil to the hydraulic cylinder via a hydraulic circuit; a relief valve that can set a relief pressure of the hydraulic circuit to either a first set pressure or a second set pressure higher than the first set pressure; a detection unit that detects at least one of a pressure of the hydraulic oil in the hydraulic circuit and a speed of the work implement; and a relief pressure changing unit that changes a relief pressure of the relief valve from the first set pressure to the second set pressure based on a detection value of at least one of the pressure of the hydraulic oil in the hydraulic circuit and the speed of the work implement when the controlled state of the work implement is the excavation state.

A drive transmission device according to one embodiment of the disclosure includes: an arm having a motor that generates a rotational force; a speed reducer that is provided in the arm and has a carrier for decelerating rotation of the motor and outputting the decelerated rotation; a bucket fixed to the carrier by a reamer bolt, the reamer bolt being inserted in a bracket through hole formed in the bucket; and a resin bush provided between an internal surface of the bracket through hole and an external lateral surface of the reamer bolt. The mechanical strength of the resin bush is lower than the mechanical strength of the bucket and the mechanical strength of the reamer bolt.

A drive transmission device according to one embodiment of the disclosure includes a single differential unit to which rotation of a motor is transmitted and two speed reducers each having an operation output shaft that is coupled to the differential unit and a carrier that changes a speed of the rotation of the operation output shaft and outputs the rotation. The two speed reducers are arranged such that they are opposed to each other along a second rotation axis, and the operation output shaft and the carrier in each speed reducer are aligned in the second rotation axis direction.

A drive transmission device includes a first member and a second member rotatably coupled about a rotation axis; a drive source generating a rotational force that drives the first member and the second member; speed reducers transmitting the rotational force from the drive source to the second member; at least two bracket portions arranged in the rotation axis direction in the second member; and a flange portion extending in a direction intersecting the rotation axis, having an overlapping region where the flange portion overlaps the bracket portion viewed from a direction along the rotation axis direction, and connecting the speed reducer and the bracket portion. A restricting member that extends in the rotation axis direction and restricts the relative rotational movement between the bracket portion and the flange portion, and a receiving portion that receives the restricting member are provided in the overlapping region.