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.

A hydraulic system includes a first electric machine connected to a first hydraulic machine and a second electric machine connected to a second hydraulic machine. An output side of the second hydraulic machine is connected to an input side of the first hydraulic machine. A hydraulic consumer is hydraulically coupled to an output side of the first hydraulic machine via a supply line and is powered by the first hydraulic machine. A return line hydraulically couples the hydraulic consumer to an input side of the first hydraulic machine. The second hydraulic machine provides a flow of hydraulic fluid to the input side of the first hydraulic machine if a requested flow from the first hydraulic machine exceeds a flow of the return line and recuperates energy if the requested flow from the first hydraulic machine is lower than the flow of the return line.

A hydraulic system includes a first electric machine connected to a first hydraulic machine and a second electric machine connected to a second hydraulic machine. An output side of the second hydraulic machine is connected to an input side of the first hydraulic machine. A hydraulic consumer is hydraulically coupled to an output side of the first hydraulic machine via a supply line and is powered by the first hydraulic machine. A return line hydraulically couples the hydraulic consumer to an input side of the first hydraulic machine. The second hydraulic machine provides a flow of hydraulic fluid to the input side of the first hydraulic machine if a requested flow from the first hydraulic machine exceeds a flow of the return line and recuperates energy if the requested flow from the first hydraulic machine is lower than the flow of the return line.

The hydraulic system according to the invention comprises a hydraulic circuit with a low-pressure region and a high-pressure region; a volume- and/or speed-variable hydraulic machine, which is driven by a first electric motor and has an inlet and an outlet and provides a volume flow of a hydraulic fluid in the high-pressure region of the hydraulic circuit. The hydraulic system according to the invention further comprises at least one movable shaft, which is arranged in the high-pressure region of the hydraulic circuit; at least one valve, which separates the high-pressure region from the low-pressure region; and at least one hydraulic fluid container, which is hydraulically connected to the low-pressure region of the hydraulic circuit. The hydraulic system according to the invention also has a discharge line, which discharges hydraulic fluid from the leakage of the hydraulic machine, and a cooling line for transporting the hydraulic fluid in order to cool the electric motor, the discharge line and the cooling line being fluidically connected to at least one of the hydraulic fluid containers.

A method for monitoring the condition of a hydraulic system of a metal forming plant is presented. The hydraulic system is coupled to or provided with a pump drivable by a drive motor for providing a working fluid and with a heat exchanger. With the presented method, the following steps are initiated or carried out by a condition-monitoring device during the operation of the hydraulic system: Determining a current cooling power of the heat exchanger; determining a current conveying power of the pump; and determining a current maintenance urgency and/or a current ageing condition of the hydraulic system on the basis of the determined current cooling power of the heat exchanger. Furthermore, a condition-monitoring device designed to carry out the presented method is presented.

A method for monitoring the condition of a hydraulic system of a metal forming plant is presented. The hydraulic system is coupled to or provided with a pump drivable by a drive motor for providing a working fluid and with a heat exchanger. With the presented method, the following steps are initiated or carried out by a condition-monitoring device during the operation of the hydraulic system: Determining a current cooling power of the heat exchanger; determining a current conveying power of the pump; and determining a current maintenance urgency and/or a current ageing condition of the hydraulic system on the basis of the determined current cooling power of the heat exchanger. Furthermore, a condition-monitoring device designed to carry out the presented method is presented.

There is provided a control module for a hydraulic system. The module comprises a tank and a plurality of valves. The tank is configured to store hydraulic fluid and is substantially cylindrical. The plurality of valves fluidly connect with the tank and are configured to control distribution of hydraulic fluid from the tank to one or more components of the system. The plurality of valves are spaced around a circumference of the tank. One or more passages fluidly connect the tank with at least one of the plurality of valves and/or a first of the plurality of valves with a second of the plurality of valves.

A load sensing valve maintains a differential pressure at a set pressure by controlling a regulator in accordance with a differential pressure between a discharge pressure of a hydraulic pump and a load pressure of hydraulic actuators. A set pressure control device controls the set pressure. A controller controls the set pressure control device to reduce the set pressure more than when the work implement is being operated, when a predetermined determination condition that includes the work implement not being operated is satisfied.

A load sensing valve maintains a differential pressure at a set pressure by controlling a regulator in accordance with a differential pressure between a discharge pressure of a hydraulic pump and a load pressure of hydraulic actuators. A set pressure control device controls the set pressure. A controller controls the set pressure control device to reduce the set pressure more than when the work implement is being operated, when a predetermined determination condition that includes the work implement not being operated is satisfied.

A control system for a hydrostatic drive system can include a hydraulic charge pump circuit having a hydraulic load and a tank. The hydraulic charge pump can be in fluid communication with the hydraulic charge pump circuit. A bypass line can extend to the tank from a junction between the hydraulic charge pump and the hydraulic load. A charge bypass valve can be disposed to control flow through the bypass line. The control system can include a control device configured to determine one or more operational parameters for the power machine and control the charge bypass valve to allow flow through the bypass line, from the hydraulic charge pump to the tank, based on the determined operational parameters during a starting operation.