A hydraulic system for a work machine includes a first control cylinder to move a boom and a second control cylinder to move a bucket. A body of the first control cylinder has a first fluid chamber and a second fluid chamber. A first control valve is connected to the first fluid chamber via a first fluid path and connected to the second fluid chamber via a second fluid path to control the first hydraulic cylinder. A bucket positioning valve is connected to the second fluid path and a third fluid path to control a second hydraulic cylinder so as to rotate the bucket. A discharge fluid path is connected to the second fluid path between the bucket positioning valve and the first control valve. A discharge control valve is provided in the discharge fluid path to be opened and closed.

method is disclosed. The method may include controlling a leading edge of an implement of a machine using a first control loop to cause the implement to align to a defined design plan; controlling a trailing edge of the implement of the machine using a second control loop to cause the implement to align to the defined design plan; and selectively altering a gain to the second control loop based on a detected deviation of the implement from the defined design plan to increase an angle of approach, using the first control loop, when the implement is positioned above the defined design plan and decrease the angle of approach, using the first control loop, when the implement is aligned to the defined design plan.

An open loop electrohydraulic bucket position control system for a work vehicle having a positionable bucket coupled to a movable boom. The bucket control system maintains a position of the bucket with respect to a frame of the vehicle as the movable boom is raised or lowered. A bucket command, determined by an operator of the vehicle, is modified based on a pre-determined relationship of the work vehicle's hardware and known and constant properties of a linkage design of the work machine. The control system includes a processor and one or more look-up tables that include data identifying implement velocities with respect to boom commands and implement velocities with respect to bucket commands. Bucket commands are modified based on a relationship between the commanded velocity of the boom and a level orientation of the bucket during the commanded heights of the boom. Modified bucket commands and boom commands adjust the position of a bucket hydraulic cylinder and a boom hydraulic cylinder.

A wheel loader includes a vehicular body, a work implement, a front wheel, and a control unit. The work implement is disposed in front of the vehicular body. The work implement has a boom. The front wheel has a tire made of an elastic material. The control unit starts to raise the boom while the tire compressed in a vertical direction rebounds and vertically stretches.

A work vehicle comprises a frame. At least one ground engaging device is coupled to the frame and configured to support the frame above a surface. A boom assembly is coupled to the frame and configured to move from a lowered position to a raised position. An attachment coupler is coupled to a distal portion of the boom assembly. At least one tilt cylinder coupled to the boom assembly and the attachment coupler. A boom lock is coupled to at least one of the frame and the boom assembly. The boom lock is configured to move from an unlocked position where the boom assembly is movable to a locked position where the boom assembly is locked to the frame in the lowered position.

A work vehicle is disclosed. The work vehicle comprises an attachment comprising a cutting edge. The attachment is configured to move from an operating position to a dump position. An operator input device is configured to receive a grade command. A grade control system is communicatively coupled to an operator input device and configured to receive the grade command and define a cutting plane. A controller is configured to receive a boom position signal, an attachment position signal, and the grade command. The controller is configured to maintain the cutting edge on the cutting plane in both the operating position and the dump position.

A hydraulic system includes a hydraulic mechanism that includes a first and a second chamber. The hydraulic system includes a control valve fluidly connected to the first chamber and a pressure sensor that is configured to measure the fluid pressure in the first chamber. The hydraulic system includes a processing unit connected to the control valve. The processing unit is configured to control a hydraulic fluid flow rate to and from the first chamber of the hydraulic mechanism via the control valve to provide a shock absorption response. The hydraulic fluid flow rate is based at least in part on a pressure measurement received from the pressure sensor. The shock absorption response is based on a simulated hydraulic accumulator.

A method of controlling a lift arm actuator and a tilt actuator to control positioning of an implement carrier coupled to a lift arm of a power machine. An activation signal is received from an enabling input device. A lift arm control signal is received from a lift arm control input commanding movement of the lift arm. The lift arm actuator is controlled responsive to receipt of both of the activation signal and the lift arm control signal to move the lift arm to a target lift arm position and to move the implement carrier to or maintain the implement carrier at a target implement carrier orientation relative to a gravitational direction.

The invention relates to a method (19) of operating a hydraulic arrangement (1) including a mounting base (5), a boom (3) that is pivotably arranged on the mounting base (5), and a Z-kinematics (2) that is arranged on the boom (3). The Z-kinematics (2) tilts a tool attachment device (10), that is pivotably arranged on the boom (3). The boom (3) is moved by a lifting hydraulic piston (7) that is connected to the boom (3) and to the mounting base (5). The Z-kinematics (2) is moved by at least a tilting hydraulic piston (11) that is connected to a lever of the Z-kinematics (2) and to the mounting base (5). On application of an input control command for changing the position of the lifting hydraulic piston (7), a compensation command is automatically generated and applied to the tilting hydraulic piston (11), to essentially maintain the attitude of the tool attachment device (10). The compensation command is generated based on the input control command for the lifting hydraulic piston (7), using a mathematical model of the hydraulic arrangement (1).

A work vehicle comprising a frame supported by a ground engaging device. A boom assembly is coupled to the frame. An attachment coupler is coupled to the boom assembly. An electronic data processor is communicatively coupled to a boom actuator, an attachment coupler actuator, a boom sensor, an attachment coupler sensor, and an operator input device. A computer readable storage medium comprising machine readable instructions that, when executed by the processor, cause the processor to receive an operator input and for a tilt forward command, command the boom actuator to move the boom assembly to a frame contact position and then command the attachment coupler actuator to move the attachment coupler towards a lower position. For a tilt rearward command, command the attachment coupler actuator to move the attachment coupler towards an upper position and then command the boom actuator to move the boom assembly towards a raised position.