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 control system includes: calculating a distribution flow rate of hydraulic fluid to be supplied to first and second hydraulic actuators based on a pressure of hydraulic fluid in the first and second hydraulic actuators and an operation amount operated to drive the first and second hydraulic actuators; calculating merged-state pump output indicating outputs of first and second hydraulic pumps required in a merged state based on the distribution flow rate; calculating separated-state pump output indicating outputs of the first and second hydraulic pumps required in the separated state based on the distribution flow rate; calculating excessive output of an engine based on the merged-state pump output and the separated-state pump output; calculating reduced output of the engine more reduced than target output by correcting the target output of the engine based on the excessive output; and controlling the engine based on the reduced output in the separated state.

A shift gearbox may include at least two driven piston-cylinder units, which are each driven via a transmission of a drive, and the piston-cylinder units may each comprise a piston, which delimits a working chamber, and each working chamber is in hydraulic connection with at least one clutch actuator and at least one gear selector via a hydraulic main line, whereby the clutch actuator comprises a working chamber delimited by a piston. A valve may be respectively arranged between each working chamber of a clutch actuator and a hydraulic main line, and both the pressure build-up and the pressure reduction in the clutch actuators may occur by adjusting the piston of a piston-cylinder unit.

A method for reducing fuel consumption of a work vehicle may include monitoring one or more loads associated with both a drive power requirement and a hydraulic power requirement for the work vehicle. In addition, the method may include actively adjusting one or more operating parameters of the work vehicle based on the monitored loads in a manner that meets the drive power requirement and the hydraulic power requirement for the work vehicle while reducing the fuel consumption of the vehicle's engine.

Disclosed is a hydraulic drive system capable of improving the fuel efficiency of a work machine by reducing the pressure loss and drag loss of a hydraulic pump. There are provided an electric motor M; a third pump P3 driven by the electric motor; a third pump hydraulic line L3 to which the delivered hydraulic fluid from the third pump is supplied; a third directional control valve V4 provided in the third pump hydraulic line, switch-operated by an arm operation device 19, and controlling the flow rate of the hydraulic fluid supplied to the arm cylinder 8 from the third hydraulic pump; and a controller 18 drive-controlling the electric motor, wherein the controller drives the third pump by the electric motor when a swing/arm combined operation is detected by pilot pressure sensors S6, S7, S10, S11.

Control system for a Continuously Variable Transmission with two pairs of conical sheaves each with an adjustable running radius, the sheave of each pair being coupled to a hydraulic actuator and the inlet port of each actuator being connected with the hydraulic actuator setting means, fed from the outlet port of a hydraulic displacement pump, connected to a supply of hydraulic medium and coupled to an electric motor which is controlled by a controller which controls the speed of the electric motor with a first control signal which is generated as a function of the actual transmission ratio of the transmission on one hand and of the desired speed of change of this transmission ratio on the other hand, all this in such a way that the speed of this first motor increases with an increase of the transmission ratio of the transmission on one hand and an increase of the speed of change of the ratio on the other hand, while the outlet port of the displacement pump is connected to the inlet of an electronically controllable pressure relief valve of which the set point is determined by a second control signal as a function of the set transmission ratio on one hand and the value of the actual torque transmitted through the transmission on the other hand, in such a way that de value of the resulting hydraulic pressure increases as the transmission ratio increases on one hand, and as the torque transmitted through the transmission increases on the other hand.

A shift gearbox, a control unit, and at least one electric motor-driven driven piston-cylinder unit with a piston, which delimits at least one working chamber, which is connected via hydraulic lines to multiple shift gearbox units of the shift gearbox and shifts these, wherein the shift gearbox units comprise at least one gear selector unit and at least one clutch units, characterised in that the control unit for shifting at least one of the shift gearbox units rotates the electric motor drive by a predetermined angle and the piston of the piston-cylinder unit is adjusted by a predetermined path (s) (path control) and the piston thereby conveys a required hydraulic volume to or from at least one shift gearbox unit.

A control system for controlling a work machine including a working unit including elements and actuators that drives the elements includes: a first hydraulic pump and a second hydraulic pump each of which supplies operating oil to at least one of the actuators; and a control device that calculates a distribution flow rate of operating oil distributed to each of the actuators based on an operating state of the working unit and switches, based on the calculated distribution flow rate, between a first state in which the operating oil supplied from both the first hydraulic pump and the second hydraulic pump is supplied to the actuators and a second state in which the actuator to which the operating oil is supplied from the first hydraulic pump is different from the actuator to which the operating oil is supplied from the second hydraulic pump.

A shift gearbox, a control unit and at least one electric-motor-driven piston-cylinder unit which has a piston and is connected via hydraulic lines to multiple shift gearbox units of the shift gearbox and shifts them, the shift gearbox units comprising at least two clutch units, characterised in that the piston of the piston-cylinder unit is in the form of a dual-action reciprocating piston, wherein the dual-action reciprocating piston sealingly separates two working chambers from each other, wherein each working chamber is connected via a main hydraulic line to one clutch each, and at least one working chamber of the dual-action reciprocating piston can be connected hydraulically via a switch valve to the reservoir.

A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53. Variable horsepower control tables 52r and 53r are provided in the electric motor rotational speed control sections 52 and 53, and limit values q1*limit and q2*limit for a virtual displacement of the variable horsepower control tables 52r and 53r are changed such that a charge state of a power storage device 170 and a charge state of another power storage device 270 become equal to each other.