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.

An hydraulic system for a working machine, the system comprising an engine, and an engine speed sensor configured to detect the engine speed; a travel pump configured to actuate a travel actuator, and a travel pump pressure sensor configured to detect the travel pump pressure; a service pump configured to actuate a service actuator, and a service pump pressure sensor configured to detect the service pump pressure; and a micro-controller unit configured to receive input values from each sensor, and configured to determine whether each input value is within a predetermined range where the engine will not stall. The micro-controller unit is configured to provide an output when at least one input value is outside the predetermined range.

Provided is a construction machine on which a hydraulic closed circuit for driving a single rod-type hydraulic cylinder and a swing hydraulic motor is mounted and that has good swing deceleration responsiveness. In this construction machine that drives each of a single rod-type hydraulic cylinder and a swing hydraulic motor in a closed circuit, a minimum passage area from a second flushing valve to a tank in a case the second flushing valve is fully open is smaller than a minimum passage area from a first flushing valve to the tank in a case the first flushing valve is fully open.

An adaptor is used to couple a prime mover to an actuator. The adaptor includes a first portion that attaches to the prime mover and a second portion that attaches to the actuator. The outer surface of the first portion is defined by at least one flat portion connected by at least one arcuate portion. The second portion has a bore configured to accept the first portion, with an inner surface shaped to complement the outer surface of the first portion. A bore through the first portion accepts a drive shaft of the prime mover therethrough where the drive shaft is configured to engage the actuator.

A hydraulic system includes a hydraulic pump to output an operation fluid, first and second hydraulic devices to be operated by the operation fluid, first and second control valves to control the first and second hydraulic device, respectively, first and second communication tubes connecting the first hydraulic device to the first control valve, a supply fluid tube connecting the first control valve to the second control valve, the supply fluid tube being configured to supply the return fluid to the second control valve, first and second connection fluid tubes disposed on the first control valve, a discharge fluid tube connected to the first control valve, first and second branching fluid tubes branched from the first and second connection fluid tubes, respectively, first and second throttles disposed on the first and second branching fluid tubes, respectively, the second throttle being smaller than the first throttle.

A hydraulic excavator (1) includes a wireless authentication device (52) performing wireless authentication with a portable key device (51) and a vehicle body controller (48) for starting an engine (15) based on authentication by the wireless authentication device (52) and an operation of a start switch (12). The wireless authentication device (52) transmits a request signal within an authenticable range and performs authentication when it receives an ID code for authentication replied from the portable key device (51) based on the transmitted request signal. The vehicle body controller (48) prohibits driving of a hydraulic actuator (5E, 5F, 5G, 5H, 2E, 2F, 3A) when the portable key device (51) is outside of the authenticable range even if a gate lock lever (13) has been switched to an unlock position.

Power machines, control systems and methods that adjust engine speed based upon actuation of user input controls that control other power machine functions such as travel functions and lift arm functions. By controlling engine speed at least partially in response to the user input devices controlling other machine functions, more optimal engine speeds can be achieved.

A hydraulic control apparatus includes: a branch path that branches from a passage connected to an oil pump and equipment to which oil is supplied by the oil pump; an accumulator connected to the branch path to accumulate and discharge high-pressure oil supplied from the branch path; a check valve provided in an oil inlet path through which oil flows into the accumulator; a balance valve unit including a reference pressure chamber, a balance valve body that is biased toward an opening side by an opening compression spring, and a control pressure chamber; and a control solenoid that introduces or discharges the high-pressure oil into or from the control pressure chamber.

A prime mover and a plurality of hydraulic actuators, a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising a plurality of working chambers, a hydraulic circuit extending between a group of one or more working chambers of the hydraulic machine and one or more of the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold. The hydraulic machine being configured to actively control at least the low-pressure valves of the group of one or more working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the group of one or more working chambers, responsive to a demand signal, wherein the apparatus further comprises a controller configured to calculate the demand signal in response to a measured property of the hydraulic circuit or one or more actuators.

A working machine includes a prime mover, a hydraulic pump driven by power of the prime mover, a cooler including a cooling fan rotated by either the power of the prime mover or hydraulic fluid delivered from the hydraulic pump, and a controller configured or programmed to perform a reduction control for reducing a target fan rotation speed that is a target rotation speed of the cooling fan in response to reduction of an actual prime mover rotation speed that is an actual rotation speed of the prime mover, and to perform, after the reduction control, a restoration control for restoring the target fan rotation speed. The controller is configured or programmed to make a difference between a reduction rate of the target fan rotation speed in the reduction control and an increase rate of the target fan rotation speed in the restoration control.