The present disclosure relates to a radial piston hydraulic device distributing flow by pilot operated check valves and an operating method thereof. The radial piston hydraulic device includes a housing, a plurality of piston assemblies, a main shaft, first pilot operated check valves, second pilot operated check valves, and a valve plate. The first pilot operated check valves have a same number as the plurality of piston assemblies and are one-to-one corresponding to the plurality of piston assemblies. The second pilot operated check valves have a same number as the plurality of piston assemblies and are one-to-one corresponding to the plurality of piston assemblies. The radial piston hydraulic device can be used not only as the hydraulic motor, but also as a hydraulic pump, and can be used in a hydraulic system that need to realize power recovery functions.

A centering apparatus for bi-directionally pivotable hopper doors. The apparatus is coupled between a frame of a hopper car and a bell crank of a hopper door. The apparatus includes a housing with a piston extending from one end. An end of the piston within the housing includes a piston head. A pair of coil springs are disposed within the housing on opposite sides of the piston head and counteract one another to bias the piston head toward the center of the housing and thus bias the hopper door toward a closed state. In a second configuration the apparatus includes a double-acting actuator with a pair of independent piston assemblies. An actuation system coupled to the actuator maintains the actuator and an associated hopper door in a closed position in a normal state and returns the hopper door to the closed position upon a failure in the system.

An actuator includes a housing defining an inlet port, a piston and a return spring disposed within the housing, and an elastically deformable element. The return spring is configured to apply a biasing force to the piston to move the piston to a spring return position. A first fluid pressure applied to the inlet port moves the piston against the biasing force of the return spring to a first actuated position in which the piston indirectly engages a stop portion of the actuator housing. A second fluid pressure, greater than the first fluid pressure, applied to the inlet port moves the piston against the elastically deformable element to compress the elastically deformable element to move the piston to a second actuated position beyond the first actuated position.

A pneumatic drive for a medical robot includes a manifold having cylinders extending in a first direction, and respective rods corresponding to the cylinders, the rods extending on one side of the cylinders in the first direction. The manifold includes air supply ports that feed the cylinders with air for moving the respective rods forward and backward. The air supply ports are provided on another side of the manifold in the first direction.

An apparatus for applying viscous material to workpieces has at least two material outlets. A needle valve is assigned to each material outlet, the valve needle of which being able to close the respective material outlet on a valve seat. Each valve needle is assigned a cylinder, in the piston chamber of which a piston is movable by pressure applied by a fluid, and which cylinder has a piston rod for impingement on the respective valve needle, the piston rod being connected to the piston, being guided out of the piston chamber on an end face facing the valve seats and extending longitudinally. The cylinders are arranged one behind the other longitudinally and the piston rod of at least one of the cylinders is guided in a sealed manner through the piston chamber of at least one further cylinder arranged closer on the valve seats.

A pneumatic actuator and control valve assembly has a housing with a control cavity for a control valve and an actuator cavity for an actuator piston and rod assembly. The control cavity and actuator cavity both have an elongated shape and are substantially parallel to each other. The control cavity has a supply port and first and second control valve outlet ports and at least one vent port with the control valve being movable through the control cavity for controlling communication between the supply port and the first and second outlet ports. The actuator cavity has first and second ports at the retracted and extended ends for shuttling the piston and within the actuator cavity between a retracted and extended end position. The housing has a first inlet and second inlet for passage of pressurized fluid to and from the housing,

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 method for controlling a control surface multirod actuator arrangement and the arrangement including: a first and a second multirod actuator configured to move or clamp around a first set of piston rods; a third multirod actuator configured to move or clamp around a second set of piston rods; a control unit configured to control motion of the first set of piston rods in a first motion mode and to control motion of the second set of piston rods in a second motion mode. Steps are moving at least one piston rod of first set of piston rods and/or clamping in parked position at least one piston rod of the second set of piston rods.

An actuator includes a housing defining an inlet port, a piston and a return spring disposed within the housing, and an elastically deformable element. The return spring is configured to apply a biasing force to the piston to move the piston to a spring return position. A first fluid pressure applied to the inlet port moves the piston against the biasing force of the return spring to a first actuated position in which the piston indirectly engages a stop portion of the actuator housing. A second fluid pressure, greater than the first fluid pressure, applied to the inlet port moves the piston against the elastically deformable element to compress the elastically deformable element to move the piston to a second actuated position beyond the first actuated position.

A dump trailer and a hydraulic cylinder assembly for the dump trailer are described herein. The cylinder assembly includes a first barrel, a second barrel rigidly coupled to the first barrel along a longitudinal axis of the cylinder assembly, and a piston assembly. The first barrel includes an inlet port for receiving vehicle hydraulic fluid and an outlet port for providing the vehicle hydraulic fluid to the vehicle. The second barrel includes an inlet port and an outlet port for providing dump trailer hydraulic fluid to a hydraulic lifting mechanism of the dump trailer. The piston assembly includes a first piston and a second piston coupled to the first piston by a shaft. The piston assembly is configured to provide the dump trailer hydraulic fluid to the hydraulic lifting mechanism to lift a box of the dump trailer when the cylinder assembly receives hydraulic fluid from the vehicle.