An electro-hydraulic actuator includes: a motor output rotative power; an external gear pump activated by the motor; a hydraulic actuator operated by a pressurized working fluid supplied by the external gear pump; a manifold block in which a flow channel forming a working fluid circuit of the hydraulic actuator is incorporated; a first portion to store the motor; a second portion to store the external gear pump, the hydraulic actuator, and a reservoir; and a coupling portion to couple the first portion and the second portion in a liquid-tight state. The coupling portion includes a communication hole through which the first portion and the second portion communicate, a rotational shaft of the motor and a driving shaft of the external gear pump are joined to each other, and the external gear pump is attached to the coupling portion while being stored in the manifold block.

A hydraulic system for a working machine, the hydraulic system includes: a hydraulic fluid reservoir; a boom actuator having an ascending chamber and a descending chamber; a first pump; a first directional control valve comprising a first ascending state configured for moving the boom in the ascending direction, a descending state configured for moving the boom actuator in the descending direction, and a first neutral state; a second pump; a second directional control valve comprising a second ascending state configured for moving the boom actuator in the ascending direction, and a second neutral state; wherein the second directional control valve further comprises a float state configured to connect at least one of the ascending and descending chambers to the hydraulic reservoir for permitting the boom to move freely in the descending and/or descending directions.

An air cylinder in which a flow rate controller is built in, has a head cover and a rod cover. A pilot air adjustment unit guides exhaust air to a switch valve of the flow rate controller as pilot air, and the switch valve is switched by an increase in the pressure of the pilot air.

A hydraulic unit includes a hydraulic circuit fluidly connected to a hydraulic actuator, and a control device to control the hydraulic circuit. The hydraulic circuit includes a hydraulic oil tank, a hydraulic pump that supplies the hydraulic oil to the hydraulic actuator from the hydraulic oil tank, a discharge flow path fluidly connecting a discharge side of the hydraulic pump to the hydraulic actuator, a valve that blocks a flow of the hydraulic oil in the discharge flow path, and a pressure sensor that detects a pressure of the hydraulic oil the discharge flow path. In a pressure holding state, when a rotational frequency of the hydraulic pump exceeds a predetermined first determination rotational frequency or when a discharge flow rate of the hydraulic pump exceeds a predetermined first determination discharge flow rate, the control device determines that the hydraulic circuit is abnormal.

A hydraulic jack including a load cylinder, a pump, a release valve and a flow regulator. The pump is configured to provide pressurized fluid to the load cylinder. The release valve is in fluid communication with the pressurized fluid. The flow regulator is configured to alter a flow path of the fluid therethrough as an inverse function of a pressure drop of the fluid across the flow regulator. The fluid regulator being in fluid communication with the release valve.

Device for recovering hydraulic energy in a machine comprising at least a first differential cylinder-piston assembly having a differential cylinder with a separate rod and base side, at least a second differential cylinder-piston assembly having a differential cylinder with a separate rod and base side, and at least one hydraulic accumulator that can be hydraulically connected to at least one of the differential cylinder-piston assemblies, wherein the differential cylinder-piston assemblies are mechanically coupled to one another, and wherein the potential energy of at least one of the differential cylinder-piston assemblies retracting under a compressive load can at least partially be stored in the hydraulic accumulator.

An apparatus for recuperating hydraulic energy in a working machine includes at least one first differential cylinder piston device with a differential cylinder and separate rod and bottom sides, and at least one hydraulic accumulator which is hydraulically connectable with the differential cylinder piston device. The potential energy of the differential cylinder piston device retracting under pressing load is at least partly storable in the hydraulic accumulator. The rod and bottom sides are connectable with each other via at least one brake valve for recirculating hydraulic fluid from the bottom side into the rod side.

An example tool includes a hydraulic actuator cylinder; a piston slidably accommodated within the hydraulic actuator cylinder, where the piston includes a piston head and a piston rod extending from the piston head along a central axis direction of the hydraulic actuator cylinder, the piston head divides an inside of the hydraulic actuator cylinder into a first chamber and a second chamber, and the piston rod is disposed in the first chamber and configured to move one or more jaws of the tool; a pump configured to provide pressurized fluid; and a sequence valve configured to block the pressurized fluid from flowing into the second chamber of the hydraulic actuator cylinder until pressure of the pressurized fluid exceeds a threshold pressure value.

The invention relates to a hydraulic device for driving an actuator to be hydraulically controlled or actuated, comprising a motor arranged in a motor housing, a compensating tank (31) for accommodating hydraulic fluid, and a hydraulic pump, which is arranged in a pump housing and driven by the motor, wherein the hydraulic pump is designed in such a way that the hydraulic pump permits conveyance of hydraulic fluid in two directions, namely in the forward direction and in the backward direction, wherein the hydraulic actuator comprises a drive cylinder, which has a first and a second cylinder chamber and a drive piston (3) arranged therebetween, to which drive piston a drive shaft (2) that can be displaced in the longitudinal direction is attached, wherein the device comprises a loading cylinder for an emergency closing spring (16), in which loading cylinder a loading cylinder chamber (12) and a loading piston (11) that can be coupled to the drive shaft (2) are arranged, wherein the emergency closing spring (16) can be loaded into a loaded or emergency-triggering readiness position by the loading piston (11), wherein the loading cylinder chamber (12) is connected to an outlet of the hydraulic pump in such a way that the loading cylinder chamber (12) can be filled with hydraulic fluid by means of the hydraulic pressure of the hydraulic pump and the loading piston can be transferred into a loading position as the emergency closing spring (16) is compressed and the loading piston can be locked there hydraulically by means of check valves (36, 37), and wherein a controlled seat valve (50) is connected to an inflow/outflow opening of the loading cylinder chamber, by means of which seat valve the emergency closing spring (16) can be transferred from the loaded readiness position into an emergency-triggering opening position, wherein both the hydraulic fluid that is contained in the loading cylinder chamber (12) and holds the emergency closing spring (16) in the readiness position and the hydraulic fluid contained in the first cylinder chamber can be discharged via the controlled seat valve (50).

A control valve device includes a valve main body formed to have an actuator port connected to an actuator, a communication passage formed in the valve main body and configured to allow the actuator port to communicate with a drain port, and an on/off valve provided between the communication passage and the drain port, and the on/off valve includes a sheet member assembled to the valve main body, an orifice provided in the sheet member, and a poppet member configured to open and close a sheet portion of the sheet member.