A hydraulic driving system includes a hydraulic cylinder with a cylinder tube and a cylinder rod, a main pump, a hydraulic-fluid path, a charge pump, a stroke position detecting unit, and a pump control unit. The hydraulic-fluid path forms a closed circuit between a main pump and the hydraulic cylinder. The cylinder rod expands or contracts depending on how hydraulic fluid is supplied and exhausted to and from first and second chambers. The charge pump replenishes hydraulic-fluid in the hydraulic-fluid path. The pump control unit performs flow-rate reduction control in which the pump control unit reduces a suction flow rate so that a suction flow rate of the main pump is equal to or less than a maximum discharge flow rate of the charge pump when the stroke position becomes closer to a stroke end of the cylinder rod than a prescribed reference position during the flow rate reduction control.

A hydraulic driving system includes a hydraulic cylinder with a cylinder tube and a cylinder rod, a main pump, a hydraulic-fluid path, a charge pump, a stroke position detecting unit, and a pump control unit. The hydraulic-fluid path forms a closed circuit between a main pump and the hydraulic cylinder. The cylinder rod expands or contracts depending on how hydraulic fluid is supplied and exhausted to and from first and second chambers. The charge pump replenishes hydraulic-fluid in the hydraulic-fluid path. The pump control unit performs flow-rate reduction control in which the pump control unit reduces a suction flow rate so that a suction flow rate of the main pump is equal to or less than a maximum discharge flow rate of the charge pump when the stroke position becomes closer to a stroke end of the cylinder rod than a prescribed reference position during the flow rate reduction control.

Aspects of embodiments of the invention relate to a spring-return actuator comprising a first piston movable between a first and a second position by pressurized fluid to move a load; a safety system comprising a second piston movable by the pressurized fluid to arm the safety system and which returns the first piston from the second position to the first position when de-energizing the 3/2 pilot valve or when the pressure of the pressurized fluid drops below a safety pressure threshold; and a differential fluid channel for providing the pressurized fluid and configured so that the first piston while working to move the load remains substantially disengaged from the safety system being armed.

Aspects of embodiments of the invention relate to a spring-return actuator comprising a first piston movable between a first and a second position by pressurized fluid to move a load; a safety system comprising a second piston movable by the pressurized fluid to arm the safety system and which returns the first piston from the second position to the first position when de-energizing the 3/2 pilot valve or when the pressure of the pressurized fluid drops below a safety pressure threshold; and a differential fluid channel for providing the pressurized fluid and configured so that the first piston while working to move the load remains substantially disengaged from the safety system being armed.

A switch valve configured to control a hydraulic fluid flow, the switch valve including a capture element which is arranged in a valve housing and displaceable into a first switching position or a second switching position, wherein a first hydraulic connection is connected with a supply connection in the first switching position and a second hydraulic connection is connected with the supply connection in the second switching position, wherein at least two pass through bore holes are provided in the capture element and extend through the capture element, wherein a first pass through bore hole provides a fluid connection between the first hydraulic connection and the supply connection in the first switching position and a second pass through bore hole provides a fluid connection between the second hydraulic connection and the supply connection in the second switching position.

A switch valve configured to control a hydraulic fluid flow, the switch valve including a capture element which is arranged in a valve housing and displaceable into a first switching position or a second switching position, wherein a first hydraulic connection is connected with a supply connection in the first switching position and a second hydraulic connection is connected with the supply connection in the second switching position, wherein at least two pass through bore holes are provided in the capture element and extend through the capture element, wherein a first pass through bore hole provides a fluid connection between the first hydraulic connection and the supply connection in the first switching position and a second pass through bore hole provides a fluid connection between the second hydraulic connection and the supply connection in the second switching position.

An actuator assembly having an end guide with a first end and a second end, the end guide defining an axis passing through the first and second end, a rod having an outer surface, the rod being movable along the axis through the end guide, a wiper disposed outwardly of the rod and within the end guide, a scraper disposed outwardly of the rod and within the end guide and spaced axially from the wiper towards the second end, a cavity defined between the wiper, the scraper, the outer surface of the rod, and the end guide, and an orifice defined in the end guide between the wiper and the scraper, the orifice defining a flow path for a lubricating fluid to flow into the cavity, wherein, the wiper and the scraper are disposed in contact with the outer surface of the rod for removing debris therefrom.

An actuator assembly having an end guide with a first end and a second end, the end guide defining an axis passing through the first and second end, a rod having an outer surface, the rod being movable along the axis through the end guide, a wiper disposed outwardly of the rod and within the end guide, a scraper disposed outwardly of the rod and within the end guide and spaced axially from the wiper towards the second end, a cavity defined between the wiper, the scraper, the outer surface of the rod, and the end guide, and an orifice defined in the end guide between the wiper and the scraper, the orifice defining a flow path for a lubricating fluid to flow into the cavity, wherein, the wiper and the scraper are disposed in contact with the outer surface of the rod for removing debris therefrom.

The invention relates to a fluid-driven drive having a movable working surface and a volume-variable cavity, further having an unstable element, wherein given a movement of the working surface in a first movement direction, the unstable element can initially be moved at least in a section with an increased expenditure of force out to an unstable point, wherein when going past the unstable point in the first movement direction, in addition to the force that is provided by fluid pressure, a force exerted by the unstable element is also available in the direction of the first movement direction, wherein given a subsequent movement of the working surface in a second movement direction opposite to the first movement direction, the unstable element can be initially moved with an increased expenditure of force out to an unstable point, wherein when passing the unstable point in the second movement direction, a lower expenditure of force is required for movement at least sectionally.

The invention relates to a fluid-driven drive having a movable working surface and a volume-variable cavity, further having an unstable element, wherein given a movement of the working surface in a first movement direction, the unstable element can initially be moved at least in a section with an increased expenditure of force out to an unstable point, wherein when going past the unstable point in the first movement direction, in addition to the force that is provided by fluid pressure, a force exerted by the unstable element is also available in the direction of the first movement direction, wherein given a subsequent movement of the working surface in a second movement direction opposite to the first movement direction, the unstable element can be initially moved with an increased expenditure of force out to an unstable point, wherein when passing the unstable point in the second movement direction, a lower expenditure of force is required for movement at least sectionally.