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 power unit with manual override control for a hydraulic system having an initial state and at least one operational state is provided, comprising: a tank for storing hydraulic fluid that moves between a first chamber and a second chamber of a hydraulic cylinder; a pump that routes the hydraulic fluid in and out of the tank; a first relief valve; a first solenoid valve configured to shift between a plurality of positions based on the at least one operational state of the hydraulic system; a first check valve connected to the first solenoid valve; a manual override control unit comprising: a second check valve; and a second solenoid valve configured to shift between a plurality of positions based on activation of a manual override control, wherein the activation of the manual override control returns the hydraulic system from the at least one operational state to the initial state.

A hydraulic system includes a hydraulic pump, a first hydraulic actuator, a second hydraulic actuator, a first control valve to control the first hydraulic actuator, a second control valve to control the second hydraulic actuator, the second control valve being arranged on a downstream side of the first control valve, and a discharge fluid tube in which the operation fluid flows. The hydraulic system further includes a first fluid tube in which a return fluid flows toward the second control valve. The hydraulic system further includes a second fluid tube in which a supply fluid flows toward the first hydraulic actuator, a third fluid tube coupling the first fluid tube to the discharge fluid tube, and a fourth fluid tube in which the return fluid flows toward the second fluid tube, the fourth fluid tube being connected to the first fluid tube.

A controller for hydraulic system of a work machine is provided. The controller is configured to perform a worktool disconnect routine to reduce pressure in a first worktool line and a second worktool line of the hydraulic system. The hydraulic system comprises a spool valve, a first worktool port connected to the spool valve by the first worktool line, a second worktool port connected to the spool valve by the second worktool line, a high pressure flow source of hydraulic fluid connected to the spool valve by a high pressure line and a low pressure tank line connected to the spool valve, the low pressure tank line at a lower pressure than a pressure of the high pressure line. When performing the worktool disconnect routine the controller is configured to: check that a power source of the work machine is operating, instruct the high pressure flow source of hydraulic fluid to provide no flow of hydraulic fluid in the high pressure line to the spool valve, instruct the spool valve to move to a first position wherein the first worktool port is connected to the low pressure tank line and the second worktool port is connected to the high pressure flow source in order to reduce a pressure in the first worktool line, and instruct the spool valve to move to a second position wherein the second worktool port is connected to the low pressure tank line and the first worktool port is connected to the high pressure flow source in order to reduce a pressure in the second worktool line.

An example valve includes: a seat member; a spool configured to be seated on the seat member to block fluid flow from a first port to a second port when the valve is in a closed state, wherein fluid at the first port applies a fluid force on the spool; a spring applying a biasing force on the spool toward the seat member, wherein as the fluid force overcomes the biasing force, the spool moves in the proximal direction off the seat member, thereby allowing fluid flow from the first port to the second port through a flow area formed between the spool and the seat member; a turbine configured to rotate as fluid flowing through the flow area flows downstream across the turbine; and an electric generator coupled to the turbine, such that rotation of the turbine causes the electric generator to generate electric power.

An example valve includes: a pressure compensation spool configured to be subjected to a first fluid force of fluid received at a first port acting in a proximal direction; a pressure compensation spring disposed in a pressure compensation chamber and applying a biasing force on the pressure compensation spool in a distal direction; a turbine configured to rotate as fluid flows through the valve; and a flow area configured to throttle fluid flow from the first port to the pressure compensation chamber, wherein fluid in the pressure compensation chamber applies a second fluid force on the pressure compensation spool in the distal direction, such that the pressure compensation spool moves to a particular axial position based on force equilibrium between the first fluid force, the second fluid force, and the biasing force to throttle fluid flow from the pressure compensation chamber to a second port.

A hydraulic system for controlling an implement on a work machine may include a hydraulic reservoir, a hydraulic pump in fluid communication with the reservoir, a central valve in fluid communication with the pump and configured for controlling the implement, a load sense pressure relief system, and a controller. The controller may be configured for controlling the central valve and the load sense pressure relief system and selecting between operating the hydraulic system at a first pressure and a second pressure based on a factor relating to implement position.

A hydraulic system includes a hydraulic pump, a first hydraulic actuator, a second hydraulic actuator, a first control valve to control the first hydraulic actuator, a second control valve to control the second hydraulic actuator, a pressure increasing portion to increasing a pressure of the operation fluid, a first discharge fluid tube connected to any one of the first control valve and the second control valve and connected to the pressure increasing portion, a second discharge fluid tube connected to the first discharge fluid tube and configured to discharge the operation fluid, a float switching valve having an allowance position, a prevention position, and a float position, the allowance position blocking the second discharge fluid tube and allowing the operation fluid to flow to the pressure increasing portion, the prevention position unblocking the second discharge fluid tube and preventing the operation fluid from flowing to the pressure increasing portion.

A hydraulic system includes first and second valve assemblies connected to a common pump. The first valve assembly includes a main valve housed inside a manifold. A pressure compensator valve maintains a constant pressure drop across a variable orifice of the main valve. A pressure limiter valve is in communication with the main valve and the pressure compensator valve, and allows an actuator connected to the first valve assembly to operate independently of the second valve assembly so that fluid flow to a work port of the first valve assembly is not interrupted by operation of the second valve assembly.

A power unit with manual override control for a hydraulic system having an initial state and at least one operational state is provided, comprising: a tank for storing hydraulic fluid that moves between a first chamber and a second chamber of a hydraulic cylinder; a pump that routes the hydraulic fluid in and out of the tank; a first relief valve; a first solenoid valve configured to shift between a plurality of positions based on the at least one operational state of the hydraulic system; a first check valve connected to the first solenoid valve; a manual override control unit comprising: a second check valve; and a second solenoid valve configured to shift between a plurality of positions based on activation of a manual override control, wherein the activation of the manual override control returns the hydraulic system from the at least one operational state to the initial state.