A method of operating a variable displacement pump in a pressurized fluid supply system for an agricultural vehicle, including maintaining a constant displacement of the pump as rotational speed of the input drive to the pump increases to a first value of 1500 rpm and thereafter adjusting the displacement of the pump to maintain a constant output fluid flow 230 L/min or reduced flow as rotational speed of the input drive to the pump increases beyond the first value to a maximum value of 2100 rpm.

A pneumatic circuit for controlling the activation of a robot with inflatable chambers includes at least one ring oscillator formed from a plurality of valves connected in series to selectively admit fluid pressure to inflate and deflate the chambers. Sequential actuation of the valves induces sequential bending and rotation of combinations of the chambers to effect motion. A switching valve changes the actuation sequence of the oscillator valves to change the direction of motion.

A shovel includes a first pump 14L; a second pump 14R; a hydraulic swing motor 21; a pump/motor 14A configured to generate an engine-assist torque in response to hydraulic oil from the hydraulic swing motor 21 during swing deceleration; an accumulator 80 configured to accumulate the hydraulic oil flowing out of the hydraulic swing motor 21 during swing deceleration; a regeneration valve 22G configured to switch open/close of transfer from a discharge port 21L to the pump/motor 14A and the accumulator 80; and a controller configured to control the regeneration valve 22G. During swing deceleration, the controller adjusts an open area of the regeneration valve 22G in such a way that a swing flowing-out pressure becomes a swing braking target pressure, and causes the hydraulic oil flowing out of the hydraulic swing motor 21 to flow into the pump/motor 14A and the accumulator 80 at the same pressure.

When option attachment has not been attached, a reserve flow/direction control valve 8 is made to operate as a center bypass cut valve. When an option attachment has been attached, switching control is performed. In the switching control, when the option attachment is not used, the reserve flow/direction control valve 8 is made to operate as a center bypass cut valve for adjusting composite opening area of a center bypass and thereby controlling the flow rate of hydraulic fluid flowing into an actuator. When the option attachment is used, the reserve flow/direction control valve 8 is made to operate so as to supply the hydraulic fluid to an option hydraulic actuator 14.

A control system includes: an engine; a first hydraulic pump and a second hydraulic pump driven by the engine; a switching device provided in a flow path that connects the first hydraulic pump to the second hydraulic pump, and configured to perform switching between a merged state in which the flow path is opened and a separated state in which the flow path is closed; a first hydraulic actuator to which hydraulic fluid discharged from the first hydraulic pump is supplied in the separated state; a second hydraulic actuator to which hydraulic fluid discharged from the second hydraulic pump is supplied in the separated state; a determining unit configured to determine whether output of the engine is limited; and a merging-separating control unit configured to control the switching device so as to perform switching to the merged state when the determining unit determines that output of the engine is limited.

An actuator unit includes two chambers defined in the cylinder; a supply passage allowing a working fluid discharged from the pump to be supplied to the two chambers; a discharge passage allowing the two chambers to communicate with the tank; a direction control valve configured to selectively communicate each of the two chambers with one of the pump and the tank; a control passage that branches from the supply passage on a side of the pump rather than the direction control valve so as to communicate the pump with the tank; a variable relief valve provided on the control passage, the variable relief valve opening so as to allow the working fluid to flow from the supply passage toward the tank when a pressure in the supply passage reaches the valve opening pressure; and a center passage that communicates the tank with an interior of the cylinder.

A working machine having a body supported on a ground engaging structure and a working arm mounted to the body so as capable of performing working operations. The working machine having a drive arrangement to propel the working machine including a prime mover and a hydrostatic transmission including at least one hydraulic pump driven by the prime mover, and at least one motor driven by hydraulic fluid. The working machine also having a hand throttle for selectively setting the power output of the prime mover, a foot throttle for dynamically adjusting the power output of the prime mover in a first mode of operation, wherein the transmission is configured to operate in a second mode of operation when a predetermined criterion is met, and in the second mode the foot throttle directly controls the speed of movement of the ground engaging structure.

Different exemplary control systems for a hydraulically powered load-handling clamp, of the type usually mountable on industrial lift trucks or automatically guided vehicles, are disclosed. The disclosed systems variably limit a hydraulic force, by which load-clamping arms move a load substantially transversely, automatically depending on the weight of the load being moved, so as to avoid excessive transverse force applied to fragile loads.

A shovel includes a first pump 14L; a second pump 14R; a hydraulic swing motor 21; a pump/motor 14A configured to generate an engine-assist torque in response to hydraulic oil from the hydraulic swing motor 21 during swing deceleration; an accumulator 80 configured to accumulate the hydraulic oil flowing out of the hydraulic swing motor 21 during swing deceleration; a regeneration valve 22G configured to switch open/close of transfer from a discharge port 21L to the pump/motor 14A and the accumulator 80; and a controller configured to control the regeneration valve 22G. During swing deceleration, the controller adjusts an open area of the regeneration valve 22G in such a way that a swing flowing-out pressure becomes a swing braking target pressure, and causes the hydraulic oil flowing out of the hydraulic swing motor 21 to flow into the pump/motor 14A and the accumulator 80 at the same pressure.

When option attachment has not been attached, a reserve flow/direction control valve 8 is made to operate as a center bypass cut valve. When an option attachment has been attached, switching control is performed. In the switching control, when the option attachment is not used, the reserve flow/direction control valve 8 is made to operate as a center bypass cut valve for adjusting composite opening area of a center bypass and thereby controlling the flow rate of hydraulic fluid flowing into an actuator. When the option attachment is used, the reserve flow/direction control valve 8 is made to operate so as to supply the hydraulic fluid to an option hydraulic actuator 14.