The invention relates to hydraulic cylinder devices and can be used in vehicle transmissions. A three-position pneumatic or hydraulic cylinder consists of a housing having end caps, two pistons, a rod, and supply channels for a working fluid, each piston being configured for limited movement along the rod as a result of a central protuberance, which separates the pistons, and peripheral protuberances on the rod, and being configured for limited movement inside the housing. The central protuberance is configured in the form of a bushing, and an annular protuberance is, configured on the inside surface of the housing. Said bushing and said protuberance form a hermetic moveable coupling of the shaft/opening type. Separate channels are provided for supplying working fluid to the chambers formed by each piston and the corresponding end of the housing, and a shared channel is provided for supplying working fluid to the chambers formed by each piston and the central protuberance and bushing; or, separate channels are provided for supplying working fluid to the chambers formed by each piston and the central protuberance and bushing, and a shared channel is provided for supplying working fluid to the chambers formed by each piston and the corresponding end of the housing.

Provided is a fluid actuator capable of safely driving a drive target. An air actuator using air as a working fluid includes an X-axis pressure sensor that measures air pressures PX+ and PX− along one drive axis, which drives a drive target in an X direction, a Y-axis pressure sensor that measures air pressures PY1+, PY1−, PY2+, and PY2− along two drive axes, which drive the drive target in a Y direction, and an acceleration detection unit that detects translational acceleration and rotational acceleration generated in the drive target on the basis of the measured air pressures PX+, PX−, PY1+, PY1−, PY2+, and PY2−.

Disclosed is a liquid chromatography solvent pump including a motor, a first piston, a second piston, and a variable output drive system coupling the motor to at least one of the first piston and the second piston. The variable output drive system includes a gearbox configured to provide a non-equal ratio between an input from the motor and an output delivered to at least one of the first piston and the second piston. The first piston and the second piston are configured to deliver a flow of solvent in a liquid chromatography system.

A valve structure (1) for driving reversible ploughs (40), comprising a first port (3) adapted to be in fluid communication with a pump (P) in a first configuration of the plough (40) and adapted to be in fluid communication with a tank (T) in a second reversed configuration of the plough (40), and a second port (4) adapted to be in fluid communication with the tank (T) in the first configuration of the plough (40) and adapted to be in fluid communication with the pump (P) in the second reversed configuration of the plough (40), a body (2) which includes a first seat (5) and a second seat (6), the seats housing respective moving spools (13, 14), a first interconnection port (7a) for the connection of the valve structure (1) to a first chamber (10a) of a first hydraulic cylinder (10) for longitudinally aligning the plough (40), and a second interconnection port (7b) for the connection to a second chamber (10b) of the first hydraulic cylinder (10), a third interconnection port (8a) for the connection of the valve structure (1) to a first chamber (12a) of a second hydraulic cylinder (12) for reversing the plough (40), and a fourth interconnection port (8b) for the connection to a second chamber (12b) of the second hydraulic cylinder (12). The valve structure (1) comprises hydraulic components configured to control the relative displacement of the spools (13, 14) to automatically control the movement of the cylinders (10, 12). A check valve (31) enables the fluid to flow in the second reversed configuration of the plough (40).

The invention relates to a self-propelled construction machine, in particular a road milling machine, stabiliser, recycler or surface miner, which has a machine frame 2 supported by at least three running gears 10A, 10B, 11A, 11B, a drive device 14 for driving at least two running gears, and a work roller 4 arranged on the machine frame. The invention also relates to a method for controlling a construction machine of this kind. The drive device 14 comprises adjustable hydraulic motors 15, 16, 17, 18 associated with the drivable running gears, which hydraulic motors have a displacement volume Vg that can be varied by an adjusting device 15A, 16A, 17A, 18A, and comprises at least one adjustable travel drive—hydraulic pump 19 driven by at least one drive motor to supply the hydraulic motors with a variable total volume flow Q of hydraulic fluid. In addition, a controller 28 is provided which is configured in such a way that a partial volume flow Q.sub.1, Q.sub.2, Q.sub.3, Q.sub.4 is determined for each adjustable hydraulic motor 15, 16, 17, 18 from the total volume flow Q provided by the at least one travel drive—hydraulic pump 19, by means of which partial volume flow the particular hydraulic motor is to be operated, and when the speed n of an adjustable hydraulic motor increases as a result of slippage of the running gear associated with the adjustable hydraulic motor, the adjusting device of the adjustable hydraulic motor is controlled in such a way that a displacement volume Vg is set for the adjustable hydraulic motor, at which displacement volume the partial volume flow determined for the adjustable hydraulic motor is maintained. The self-propelled construction machine according to the invention is characterised in that a hydraulic flow divider is not required.

A forklift truck includes a carriage that moves up and down by a mast assembly in a multi-stage structure including an outer mast, a first inner mast accommodated in the outer mast, and a second inner mast accommodated in the first inner mast. The forklift truck includes a first lift cylinder configured to move the first inner mast up and down; a second lift cylinder configured to move the second inner mast up and down and having a pressure reception area less than a pressure reception area of the first lift cylinder. A first lift hydraulic line supplies hydraulic oil to the first lift cylinder. A second lift hydraulic line supplies hydraulic oil to the second lift cylinder. A pressure regulating valve is provided to increase a pressure of the hydraulic oil to a pressure capable of driving the second lift cylinder.

Combination linear and rotary actuators are disclosed. The linear and rotary actuators have a housing defining a cylindrical interior space and a pair of pistons located inside the cylindrical interior space. An inner bearing cylinder is provided that has spaced-apart ball bearings arranged in a helical pattern on its surface that engage with a structure having an inner surface with helical grooves therein. The structure at least indirectly engages a linear drive piston that is slidably mounted in the housing, and provides rotational movement thereto. The linear drive piston has an input shaft that has ball bearings on its surface, and is inserted inside the output shaft of a revolution piston that has an inner surface with linear grooves. The actuators use hydrostatically charged integral bearing races that activate during operation to reduce friction. Combination linear and rotary actuators with double actuation output shafts are also provided.

Disclosed is a piston-cylinder assembly of a hydraulic press, which includes a basic cylinder and a first and second piston. A ring cylinder is formed above the basic cylinder as a continuation of the cylinder structure. The first piston is located inside the basic cylinder in the bottom part of the basic cylinder and the second piston is located above the first piston in the top part of the cylinder structure. The piston-cylinder assembly has a first hydraulic fluid space below the first piston and a second hydraulic fluid space below the second piston and the piston-cylinder assembly includes a unified hydraulic fluid channel in flow connection to the first hydraulic fluid space in order to provide a pressure effect in the first piston and to the second hydraulic fluid space in order to provide a pressure effect in the second piston.

An apparatus (1) for supporting an explosive device (13) including a base member (3), one or more support members (11) and a fluid aperture (19). The base member (3) includes a base member aperture (5) to provide a passage (7) to a base chamber (9) of the base member (3). The one or more support members (11) are telescopically receivable through the base member aperture (5) and into the base chamber (9), wherein the one or more support members (11) support the explosive device (13). The fluid aperture (19) allows pressurised fluid into the base chamber (9) to force the one or more support members (11) towards an extended configuration (23) such that at least part of the one or more support members (11) are telescopically extended out of the base chamber (9).

Provided is a fluid actuator capable of safely driving a drive target. An air actuator using air as a working fluid includes an X-axis pressure sensor that measures air pressures PX+ and PX− along one drive axis, which drives a drive target in an X direction, a Y-axis pressure sensor that measures air pressures PY1+, PY1−, PY2+, and PY2− along two drive axes, which drive the drive target in a Y direction, and an acceleration detection unit that detects translational acceleration and rotational acceleration generated in the drive target on the basis of the measured air pressures PX+, PX−, PY1+, PY1−, PY2+, and PY2−.