The construction machine includes: a control valve that switchingly supplies hydraulic fluid from a hydraulic pump to a hydraulic actuator; a control valve drive device that supplies pilot secondary hydraulic fluid to the control valve in accordance with an operation of an operation lever device; a pilot hydraulic pump that supplies pilot primary hydraulic fluid to the control valve drive device; a pressure accumulation device that recovers return hydraulic fluid returned from the hydraulic actuator. The construction machine further includes: a check valve provided in a line between the pilot hydraulic pump and the control valve drive device; a pressure reducing valve that supplied the hydraulic fluid accumulated in the pressure accumulation device; a flow rate reduction device; and a controller that controls the flow rate reduction device in accordance with the pressure in the line between the check valve and the control valve drive device.

A servo valve including a piezo-electric actuator, a flexible linkage, and control valves. The piezo-electric actuator is actuatable along a piezo stack axis. The flexible linkage is coupled to the piezo-electric actuator at opposite axial ends of the actuator. Control valves are disposed at laterally opposite sides of the piezo stack axis and include respective valve stems coupled to the flexible linkage. The flexible linkage may be configured to transfer motion of the piezo-electric actuator along the piezo stack axis to a motion of the valve stems along an amplification axis that is transverse to the piezo stack axis to open and close the control valves. A symmetric actuation element incorporating the piezo-electric actuator, or a different actuator, may have first and second chambers at laterally opposite sides thereof, and be electrically actuatable along an actuation axis to open and close supply and return ports to control fluid communication with respective first and second work ports of respective first and second chambers.

In one aspect, a system for controlling the supply of hydraulic fluid to an implement may include a pump, a control valve coupled to the pump and first and second fluid lines provided in flow communication with output ports of the control valve. The system may also include a pressure control valve configured to regulate a pressure of the hydraulic fluid being supplied to the control valve such that the hydraulic fluid is supplied to the control valve at a first pressure for raising at least one ground-engaging component of the implement and a second pressure for lowering the ground-engaging component(s). Moreover, the system may include a bypass line in fluid communication with the pressure control valve such that fluid diverted through the bypass line actuates the pressure control valve to adjust the fluid pressure of the hydraulic fluid supplied to the control valve between the first and second pressures.

A hydraulic system according to one aspect of the present disclosure includes: control valves interposed between a main pump and hydraulic actuators; and solenoid proportional valves connected to pilot ports of the control valves. Among the solenoid proportional valves, a first solenoid proportional valve and a second solenoid proportional valve are connected to a pair of pilot ports of a particular control valve, respectively. The first solenoid proportional valve and the second solenoid proportional valve are directly connected to an auxiliary pump. The solenoid proportional valves except the first solenoid proportional valve and the second solenoid proportional valve are connected to the auxiliary pump via a switching valve. The switching valve includes a pilot port that is connected, by a switching pilot line, to a first pilot line between the first solenoid proportional valve and the particular control valve.

A servo regulator includes servo piston, a first pressure chamber and a second pressure chamber, a spool, a biasing member provided on an outer periphery of the spool and configured to bias the spool, a first support portion configured to support one end portion of the biasing member when the spool is moved to a first direction where the pressure in the first pressure chamber is raised, and a second support portion configured to support other end portion of the biasing member when the spool is moved to a second direction where the pressure in the second pressure chamber is raised, wherein at least one of the first support portion and the second support portion is detachably provided on the spool.

A device mounting structure for mounting a load maintaining mechanism on a hydraulic cylinder, a pipe for suppling and discharging working oil to and from the hydraulic cylinder being connected to the load maintaining mechanism such that the working oil is led thereto, includes a single coupling portion that includes a screw hole and is provided on the hydraulic cylinder, and a bracket to which the load maintaining mechanism is fixed, the bracket being coupled to the coupling portion via a first screw member that is screwed into the screw hole, wherein the bracket includes a first through hole through which the first screw member is passed so as to leave a gap in a radial direction.

A damping valve includes a valve seat member that includes a port and a first valve seat, a shaft member disposed on the valve seat member, an annular main valve element that is mounted on the shaft member, seats on and separates from the first valve seat, and includes a second valve seat on an opposite side of the valve seat member, a sub valve element that is mounted on the shaft member, and seats on and separates from the second valve seat, a valve-element-between chamber that is disposed between the main valve element and the sub valve element, and on an inner peripheral side of the second valve seat, a restrictive passage that causes the port to be communicated with the valve-element-between chamber to provide a resistance to a flow of a passing fluid, a main valve element biasing part biasing the main valve element to the valve seat member side, and a sub valve element biasing part biasing the sub valve element to the main valve element side. The restrictive passage is formed of a ring-shaped gap between the main valve element and the shaft member.

A valve assembly is disclosed. The valve assembly includes a valve housing defining a bore, a first valve, and a second valve. The first valve and the second valve are disposed within the bore and each of the first valve and the second valve include a first end and a second end. Further, the first end of the first valve and the first end of the second valve are configured to contact each other. The valve assembly further includes a pilot chamber defined within the bore. The pilot chamber is configured to receive a pilot fluid. Further, a pressure of the pilot fluid inside the pilot chamber is controlled to permit independent movement of the first valve and the second valve within the bore.

A blowout preventer control system comprising: a blowout preventer comprising one or more casing shear rams and one or more blind shear rams; a casing shear ram close chamber; a blind shear ram close chamber; a first SPM valve; a second SPM valve; a first solenoid valve; a microprocessor; and a hydraulic fluid source.

To obtain an electromagnetic actuator capable of improving a thrust force of a movable element. Provided is an electromagnetic actuator, including: a stator, which has a first surface at one end in an axial direction and a second surface at another end in the axial direction, and is made of a soft magnetic material having a tubular space formed in the axial direction; and a movable element, which is disposed in the tubular space, and is configured to move along the axial direction, wherein the stator includes: a coil; a core portion; and a protrusion portion, wherein the movable element includes a movable element core made of a soft magnetic material and a permanent magnet, and wherein at least one of a radially inner side and a radially outer side of the permanent magnet is covered by a movable element core.