A hydraulic system for a working machine includes a feeding pump; and a plurality of variable displacement hydraulic machines being connected in parallel to the feeding pump; At least one of the variable displacement hydraulic machines being is adapted to drive a ground engagement element of the working machine, and at least one of the variable displacement hydraulic machines is adapted to drive a vibrator for vibrating a ground engagement element of the working machine.

An actuation pressure to actuate one or more hydraulic actuators may be determined based on a load on the one or more hydraulic actuators of a robotic device. Based on the determined actuation pressure, a pressure rail from among a set of pressure rails at respective pressures may be selected. One or more valves may connect the selected pressure rail to a metering valve. The hydraulic drive system may operate in a discrete mode in which the metering valve opens such that hydraulic fluid flows from the selected pressure rail through the metering valve to the one or more hydraulic actuators at approximately the supply pressure. Responsive to a control state of the robotic device, the hydraulic drive system may operate in a continuous mode in which the metering valve throttles the hydraulic fluid such that the supply pressure is reduced to the determined actuation pressure.

A multi-control hydraulic circuit supplies receivers with hydraulic fluid delivered by a pump with an output controlled by the pressure of a control line depending on a load pressure of the receivers, and delivers the hydraulic fluid at a regulated pressure. The hydraulic circuit consists of hydraulic modules each associated with a receiver having a distributor which regulates the variable output supplying the receiver via a pressure compensator connected at its inlet to the outlet of the variable choke of the distributor, and at its outlet. The plunger manages the connection between its inlet and its outlet. The pressure compensator has a fluid link equipped with a choke and connects the outlet to the control line, irrespective of the position of the plunger.

A hydraulic drive system for an agricultural implement includes a high pressure supply line configured to provide hydraulic fluid under pressure. The hydraulic drive system also includes a low pressure return line configured to return the hydraulic fluid. The hydraulic drive system further includes a plurality of hydraulic motors and coupled to the high pressure supply line. The hydraulic drive system still further includes a plurality of cylinder systems isolated from the high pressure supply line to minimize a supply pressure of the hydraulic fluid provided from a pump coupled to the high pressure supply line and to minimize throttling losses in the hydraulic drive system during operation of the hydraulic drive system.

A hydraulic drive system for an agricultural implement includes a high pressure supply line configured to provide hydraulic fluid under pressure. The hydraulic drive system also includes a low pressure return line configured to return the hydraulic fluid. The hydraulic drive system further includes a plurality of hydraulic motors and coupled to the high pressure supply line. The hydraulic drive system still further includes a plurality of cylinder systems isolated from the high pressure supply line to minimize a supply pressure of the hydraulic fluid provided from a pump coupled to the high pressure supply line and to minimize throttling losses in the hydraulic drive system during operation of the hydraulic drive system.

A construction machine is provided that can cause each hydraulic actuator to accurately operate according to operation by an operator in combined operation in which a hydraulic fluid of a hydraulic pump is subjected to flow dividing and is supplied to plural hydraulic actuators. A controller 10, in a case of determining that combined operation is being carried out, controls a regulator 7a in such a manner that the delivery flow rate of a hydraulic pump 7 becomes larger than the total target flow rate of plural hydraulic actuators 4a, 5a, and 6a, and controls the respective opening amounts of plural directional control valves 8a1, 8a3, and 8a5 in such a manner that the difference between the respective target flow rates of the plural hydraulic actuators and the respective inflow flow rates of the plural hydraulic actuators sensed by velocity sensors 12 to 14 becomes small.

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.

Method for the load-dependent regulation of a hydrostatic drive (1), with a closed hydraulic fluid circuit comprising a first hydraulic motor (5) and, parallel to this, a second hydraulic motor (6), whereby both hydraulic motors (5 and 6) are capable of being powered by a hydraulic pump (3) via a high-pressure line (7) and a low-pressure line (8) and are mechanically coupled to each other via a transmission (70). The displacement of the first hydraulic motor (5) can be adjusted proportionally to an electrical signal of an electronic control system (50) by means of an electro-proportional control valve (10) and the displacement of the second hydraulic motor (6) can be adjusted by means of a pressure-proportional control valve (20) which is hydraulically connected to the high-pressure line (7) via a control pressure line (21). The pressure-proportional control valve can be activated by means of a control pressure which is dependent on the high pressure. By means of automatic opening of the pressure-proportional control valve (20) dependent on the high pressure, proportional to the exceedance of a predefinable pressure limit in the high-pressure line (7), the displacement of the second hydraulic motor (6) is adjusted by means of a second servo control unit which can be controlled via the pressure-proportional control valve (20). By means of the electronic control system (50), the actual volume flow passing through the first hydraulic motor (5) is determined and compared with a target value for the volume flow. Based on a deviation between the actual and target value for the volume flow, the electronic control system (50) calculates an adapted control signal and transmits this to the electro-proportional control valve (10), as a result of which the displacement of the first hydraulic motor (5) is adaptable by means of a first servo control unit (14), which is controlled via the electro-proportional control valve (10).

An actuation pressure to actuate one or more hydraulic actuators may be determined based on a load on the one or more hydraulic actuators of a robotic device. Based on the determined actuation pressure, a pressure rail from among a set of pressure rails at respective pressures may be selected. One or more valves may connect the selected pressure rail to a metering valve. The hydraulic drive system may operate in a discrete mode in which the metering valve opens such that hydraulic fluid flows from the selected pressure rail through the metering valve to the one or more hydraulic actuators at approximately the supply pressure. Responsive to a control state of the robotic device, the hydraulic drive system may operate in a continuous mode in which the metering valve throttles the hydraulic fluid such that the supply pressure is reduced to the determined actuation pressure.

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.