Provided is an outboard motor raising and lowering apparatus that is capable of automatically changing the speed of raising/lowering an outboard motor according to a status of the outboard motor. The outboard motor raising and lowering apparatus (1) includes: a first fluid passage that connects a pump (42), a second chamber(s) of one or more tilt cylinders (14), and a second chamber(s) of one or more trim cylinders (12); a second fluid passage that is connected to the first chamber of at least one of the one or more trim cylinders; and a switching valve (60) provided at the second fluid passage.

A hydraulic lifting column comprising a base structure, a head structure and a lifting structure. The lifting structure comprising a hydraulic power unit and hydraulic linear actuators extending between the base structure and the head structure, the hydraulic power unit acting on the hydraulic linear actuators. The lifting structure comprising four linear actuator units with a mutually parallel, vertically oriented working direction. Each linear actuator unit comprising a double cylinder having two-cylinder bores arranged next to one another and two piston structures with piston rods oriented parallel to one another and extendable in opposite directions from the double cylinder. The four lower piston rods are connected to the base structure at the corners of a first quadrilateral and the four upper piston rods are connected to the head structure at the corners of a second quadrilateral.

Provided is an outboard motor raising and lowering apparatus that is capable of automatically changing the speed of raising/lowering an outboard motor according to a status of the outboard motor. The outboard motor raising and lowering apparatus (1) includes: a first fluid passage that connects a pump (42), a second chamber(s) of one or more tilt cylinders (14), and a second chamber(s) of one or more trim cylinders (12); a second fluid passage that is connected to the first chamber of at least one of the one or more trim cylinders; a switching valve (60) provided at the second fluid passage; and a control section (100) configured to control the switching valve with reference to a watercraft status signal.

Actuators and devices are provided for imparting a rotary movement and comprising in a longitudinal direction first and second hydraulic cylinders, characterised in that the first driver is a linear hydraulic cylinder comprising a first piston, and that the second driver is a linear hydraulic cylinder comprising a second piston, and in that the devices include a member for converting linear motion into rotary motion in order to convert a translation movement of the second piston into a rotary movement.

A multi-stage shift pack assembly and method includes a frame assembly, a tool mounting movable relative to the frame assembly, and a removable cylinder shift pack secured to the frame assembly and having at least two cylinders that are independently actuatable for moving the tool mounting relative to the frame assembly a desired amount. The tool mounting is moved relative to the frame assembly by independently actuating cylinders of the removable cylinder shift pack.

A hydraulic cylinder may include a cylindrical body, a first piston rod coupled with a first end of the body, and a second piston rod coupled with a second end of the body. The first piston rod may include a cavity with an inner diameter, and the second piston rod may have an outer diameter that is smaller than the inner diameter of the cavity. The hydraulic cylinder is adjustable from a closed position, in which a length of the first piston rod is housed inside the body and a length of the second piston rod is housed inside the cavity of the first piston rod, to an extended position, in which the first piston rod extends through the first end of the body and the second piston rod extends through the second end of the body.

An example aircraft includes (i) a landing gear having a chassis, an axle, and wheels mounted to ends of the axle; (ii) a hydraulic actuator including a cylinder, a first piston coupled to the chassis, and a second piston coupled to the axle; and (iii) a directional control valve including: inlet ports configured to be fluidly coupled to a source of pressurized fluid, tank ports configured to be fluidly coupled to a tank, and workports configured to be fluidly coupled to the hydraulic actuator.

An agricultural machine includes a frame, and a lifting unit configured to vary a height of an operating unit with respect to a supporting surface for the machine. The lifting unit includes hydraulic cylinder with a liner and first and second pistons both slidingly housed inside the liner and arranged in series to define first and second chambers inside the liner, wherein the first and second pistons are controllable independently. The lifting unit includes a pressure stabilizer in fluid connection with the first chamber and that controls a pressure in the first chamber so that the first piston moves therein as a force generated on the first piston varies. A second control element for the second chamber carries out a volumetric control of the second chamber to control a position of the second piston regardless of a pressure inside the second chamber.

The subject matter of this specification can be embodied in, among other things, a fluid actuator system including a fluid actuator having a housing having an inner wall defining an interior cavity, a piston having a piston head configured for reciprocal movement within the interior cavity, the piston head contacting the inner wall and dividing the interior cavity into a first fluid chamber and a second fluid chamber, a first valve configured to control fluid flow between the first fluid chamber and a bypass conduit, and a second valve configured to control fluid flow between the bypass conduit and the second fluid chamber.

In an exemplary method of monitoring performance of a fluid driven actuator for a valve, pressurized fluid is supplied through an actuator supply line to an inlet port of the actuator during a first time period to operate the actuator from a normal position to an actuated position. Pressure changes corresponding to a fluid flow condition in the actuator supply line are measured during the first time period, with the measured pressure changes defining a valve cycle pressure profile including a first inflection point corresponding to movement of the actuator from the normal position to the actuated position. The valve cycle pressure profile is analyzed to identify a non-compliant condition in at least one of the valve and the actuator. An output communicating the identified non-compliant condition is then generated.