A working machine including a movable implement, a hydraulic actuator for displacing the implement, and a hydraulic control system for enabling an operator to control movement of the implement. The control system allows the implement to be returned to a desired position or state, such as a return to dig position or a return to float state, in a single automated operation that is initiated by the operator actuating a switch at the same time as moving a joystick in a desired direction. A pilot-operated valve is used to supply hydraulic fluid under pressure to the actuator acting on the implement and the operation of the joystick is detected by means of a pressure sensor connected to a control line of the pilot-operated valve.

A hydraulic cylinder spool valve device, which extends and retracts a cylinder rod of a hydraulic cylinder, includes: a first spool valve having a first dead band and a first opening characteristic; a second spool valve having a second dead band and a second opening characteristic; and a controller performing communication with the hydraulic cylinder by using the first spool valve and positioning the second spool of the second spool valve within the second dead band and performing communication with the hydraulic cylinder by using the second spool valve and positioning the first spool of the first spool valve within the first dead band, and adjusting a characteristic of a switching dead band between the first opening characteristic and the second opening characteristic.

A hydraulic system includes: a control valve including a first and second pilot port to move an actuator in a first and second direction respectively; a first line that connects between a pilot pressure source and first pilot port; a solenoid proportional valve provided on first line; a second line that branches off from first line at the solenoid proportional valve's position upstream and that is connected to second pilot port; a switching valve provided on the second line and including a spring to keep the switching valve in a closing position, wherein switching valve allows communication between second pilot port and tank, and a pilot port to shift the switching valve from closing to an opening position, wherein switching valve allows second pilot port to communicate with pilot pressure source; and a third line that connects between the switching valve's pilot port and a portion of the first line.

A hydraulic system includes a hydraulic pump to output an operation fluid, a hydraulic apparatus to be activated by the operation fluid, an operating member to operate the hydraulic apparatus, an operation valve to determine a pressure of the operation fluid in accordance with operation of the operating member, the operation fluid being supplied to the hydraulic apparatus, a first fluid tube connecting the hydraulic pump to the operation valve, a first working valve disposed on the first fluid tube, the first working valve being configured to change an opening aperture of the first working valve, a first outputting fluid tube connected to a section of the first fluid tube between the operation valve and the first working valve, and a second working valve disposed on the first outputting fluid tube, the second working valve being configured to change an opening aperture of the second working valve.

A pressure operating device includes several valves disposed at fluid channels of a base such that high pressure fluid compels the valves to a closed position; a pressure disk disposed above the base and several swing arms extending from a swing seat; a guide member having an axial hole and several guide channels surrounding the axial hole, and an operating rod unit extending through the axial hole for coupling with the swing seat in such a manner that movement of the operating rod unit into one guide channel results in swinging of the swing seat into the guide channel, thereby swinging a respective one of the swing arms above and pressing a corresponding valve downward and opening the corresponding valve to permit entry of the high pressure fluid into the pressure operating device while remaining the swing arms are spaced apart from and maintaining remaining valves in the closed position.

A joystick controller is provided that has a housing and a correlated output device supported within the housing. A socket has a shaft and a base. As the shaft is moved, the base interacts with the correlated output device to control a vehicle and/or an attachment. The operator user grips a handle that is transversely coupled to the shaft at an angle. The joystick has two control axes that provide a rotational feel for the control of the vehicle and/or attachment.

A valve device includes a valve body, a drain chamber wall configured to define a drain chamber, a drain port formed in the drain chamber wall facing the valving element, and a drain passage configured to guide drain fluid from another valve device to the drain chamber, wherein at least one of the drain chamber wall and the valving element includes a communicating passage configured to allow the drain port to communicate with the drain chamber when the movement of the valving element is restricted by the drain chamber wall.

A spool valve is provided. A valve housing has a pilot fluid passage, and a first portion and a second portion lengthwisely spaced apart from each other. A spool is movably inserted in the valve housing, and includes a plug able to enter the pilot fluid passage between the first portion and the second portion to change a flow area of the pilot fluid passage following movement of the spool. A hydraulic machine provides that when pilot fluid is supplied to the pilot fluid passage through the first portion, at least a portion of the supplied pilot fluid is provided to the holding valve through the second portion. The holding valve allows a flow of working fluid from the first chamber to the spool valve, and the spool moves to a third position to forward working fluid to the second chamber.

A hydraulic system includes: a control valve including a first and second pilot port to move an actuator in a first and second direction respectively; a first line that connects between a pilot pressure source and first pilot port; a solenoid proportional valve provided on first line; a second line that branches off from first line at the solenoid proportional valve's position upstream and that is connected to second pilot port; a switching valve provided on the second line and including a spring to keep the switching valve in a closing position, wherein switching valve allows communication between second pilot port and tank, and a pilot port to shift the switching valve from closing to an opening position, wherein switching valve allows second pilot port to communicate with pilot pressure source; and a third line that connects between the switching valve's pilot port and a portion of the first line.

A back-up load retention system includes a retention line which is connected to a load, a counterweight unit which is connected to the retention line, and a double-acting hydraulic cylinder which is connected to the counterweight unit. The counterweight unit maintains a tension force in the retention line. The double-acting hydraulic cylinder brakes and/or stops the load in a case of a failure in a main lifting system.