Embodiments of the invention provide for a system and method for operating a hydraulic tool near high-voltage components. The hydraulic tool may be connected to couplers and receiving hydraulic fluid from a pump and returning the hydraulic fluid to a tank in an open center system or returning the hydraulic fluid to a tank in a closed center system. In the event of a loss in pressure the valves in the system change state stopping the flow of hydraulic fluid to the hydraulic tool without the use of electrical components.

Method for controlling a hydraulic system for a working machine, the system including a first electric machine connected to a first hydraulic machine the first hydraulic machine including an input side and an output side a second electric machine connected to a second hydraulic machine the second hydraulic machine including a high-pressure side and a low-pressure side the high-pressure side connected to the input side; a hydraulic consumer coupled to the output side via a supply line and configured to be powered by the first hydraulic machine; a first return line hydraulically coupling the hydraulic consumer to the input side and to the high-pressure side; wherein the method includes detecting a return flow from the hydraulic consumer through the first return line; and controlling the second hydraulic machine to maintain a pressure in the first return line at a pressure level higher than a predetermined minimum pressure level.

A pneumatic control device includes a functional assembly that has an interruption valve device for the selective opening or interruption of at least one main working channel used for the pneumatic control of a pneumatic actuator. The functional assembly also contains a manually actuatable valve device that is connected to the interruption valve device by means of at least one auxiliary working channel and which enables manual pneumatic control of the connected actuator, if the at least one main working channel is interrupted by the interruption valve device at the same time. A process control device can also be equipped with a control device of this type.

A turbine valve actuator (100) controls a valve unit of a media-operated consumer unit, such as a steam or gas turbine, and has an actuating part drive (102) with a movable actuating part (104), a first media space (106) and a second media space (108). A pressure build up in the first media space (106) attempts to cause a movement of the actuating part (104) in a first direction (R). A pressure build-up in the second media space (108) attempts to cause a movement of the actuating part (104) in an opposing second direction (GR). The first media space (106) can be supplied with a fluid in predeterminable amounts by a supply (110). The second media space (108) is acted upon by a hydraulic accumulator (112) provided with a preload pressure and permanently connected to the second media space (108).

A valve includes a valve body, an inlet orifice in fluid communication with a first fluid volume, an outlet aperture in fluid communication with a second fluid volume and in selective fluid communication with the inlet orifice by a first fluid flow path, an activation member axially movable relative to the valve body, and a plunger axially movable within the valve body. The plunger includes an aperture therethrough defining a second fluid flow path between the first and second fluid volumes. The valve is operable in a first mode in which fluid flow is only permitted along the first fluid flow path in response to manual actuation of the activation member. The valve is operable in a second mode in which fluid flow is only permitted along the second fluid flow path when a pressure difference between the first and second fluid volumes reaches a predetermined value.