A hydraulic system includes: a boom cylinder to move a boom; a working tool cylinder to move a working tool attached to the boom; a boom control valve to control the boom cylinder; a working tool control valve to control the working tool cylinder; a horizontal control valve having: an activating position to allow a horizontalizing operation of the working tool; and a stopping position to stop the horizontalizing operation; and a controller device having: a first information obtaining portion to obtain permission and non-permission to the horizontalizing operation; a second information obtaining portion to obtain at least one of upward operation and upward movement of the boom; and a horizontal controller to set the horizontal control valve to the stopping position when the first information obtaining portion obtains the non-permission and the second information obtaining portion obtains one of the upward operation and the upward movement.

A work machine includes a mainframe, a boom moveable relative to the mainframe, a work implement coupled to and moveable relative to the boom. The work machine further includes a work-implement operator control configured to transmit a signal indicative of a work-implement movement command, a boom operator control configured to transmit a signal indicative of a boom movement command, and a boom sensor configured to detect a movement of the boom and transmit a signal indicative of the detected movement of the boom. The work implement further includes a controller configured to receive signals from the work-implement operator control, the boom operator control, and the boom sensor. The controller is further configured transmit a signal to cause movement the work implement relative to the boom based on the detected movement of the boom and the work-implement movement command.

A method for automatically adjusting the position of an implement of a lift assembly of a work vehicle includes determining a tilt transition boom angle for the lift assembly, determining a closed-loop control signal associated with controlling movement of the implement based at least in part on the tilt transition boom angle, generating a valve command signal based at least in part on the closed-loop control signal, and controlling an operation of at least one valve associated with the implement based at least in part on the valve command signal to maintain the implement at a target implement angle as a boom of the lift assembly is being moved across a boom travel range.

A wheel loader includes a vehicle body, a work implement, a bucket-to-ground angle detection section, and a control section. The work implement operates with respect to the vehicle body and includes a bucket or a fork. The bucket-to-ground angle detection section detects information on a tilt angle of the bucket or the fork with respect to a gravity direction. The control section controls the tilt angle of the bucket or the fork with respect to the gravity direction based on a detection value of the bucket-to-ground angle detection section.

A method for automatically adjusting the position of an implement of a lift assembly of a work vehicle includes determining a tilt transition boom angle for the lift assembly, determining a closed-loop control signal associated with controlling movement of the implement based at least in part on the tilt transition boom angle, generating a valve command signal based at least in part on the closed-loop control signal, and controlling an operation of at least one valve associated with the implement based at least in part on the valve command signal to maintain the implement at a target implement angle as a boom of the lift assembly is being moved across a boom travel range.

A valve system, including first, second, third and fourth ports, a first flow path connecting the first and second ports, a second flow path connecting the third and fourth ports, with valves connected in the first and second flow paths, and energizable to block the same. A third flow path connects the first and second ports and a fourth flow path connects the third and fourth ports. The third and fourth flow paths are more restricted than the respective first and second flow paths. A fifth flow path connects the first and fourth ports and a sixth flow path connects the second and third ports. When the third and fourth flow paths are open, the first, second, fifth, and sixth flow paths are blocked. When the first and second flow paths are open, the third, fourth, fifth, and sixth flow paths are blocked. When the fifth and sixth flow paths are open, the first, second, third, and fourth, flow paths are blocked.

A method for automatically adjusting the position of an implement of a lift assembly may generally include receiving a signal indicative of a position and/or a movement parameter of loader arms of the lift assembly and receiving a signal indicative of a pressure of a hydraulic fluid supplied within the lift assembly. The method may also include calculating a first correction signal associated with adjusting the position of the implement, wherein the correction signal is calculated by inputting the position and/or the movement parameter and the fluid pressure into a control equation based on a model of the operational dynamics of the lift assembly. In addition, the method may include generating a valve command signal based at least in part on the correction signal and transmitting the valve command signal to a valve for maintaining the implement at a fixed orientation relative as the loader arms are being moved.

A method of operating a digging machine, including damping the response of a boom hydraulic cylinder operationally connected to a boom arm and actuating a bucket hydraulic cylinder operationally connected to a bucket.

Power machines and control systems used thereon include a lift cylinder, a tilt cylinder, and a slave cylinder mechanically connected to assist the lift cylinder with raising a boom. With a lift control valve controlled to cause extension of the lift cylinder to raise the boom, pressure from a hydraulic source is provided to the slave cylinder to aid in raising the boom. Resulting increased pressure on a side of the slave cylinder opens load holding valves, allowing hydraulic pressure from the tilt cylinder to be communicated to the slave cylinder such that tilt cylinder pressure due to a heavy load on an implement aids in raising the boom.

A lift arm structure for a power machine with a frame can include a multi-bar linkage that is pivotally secured to the frame and a leveling link that is pivotally secured to the multi-bar linkage. The leveling link can be configured to transmit force from the leveling link to an implement as the multi-bar linkage is actuated to raise or lower the implement, including via a multi joint member that is pivotally secured to the leveling link, the multi-bar linkage, and an actuator that is configured to move the implement.