Systems and methods include providing an aircraft with a direct drive dual-concentric valve (D3V) having a body, an outer secondary spool coaxially located within a bore of the body and linearly displaceable relative to the body, an inner primary spool coaxially located within a bore of the secondary spool and linearly displaceable relative to the secondary spool and the body, and multiple motor assemblies coupled to the primary spool that provide selective displacement of the primary spool or the secondary spool. Each motor assembly includes a clutching mechanism that selectively couples a motor of the motor assembly to and from the primary spool.

Various exemplary embodiments relate to an engine including a cylindrical cassette that converts linear into rotational motion. The linear motion is provided by a normal cylinder and valve mechanism driving pistons in a reciprocating motion, and the rotational motion is transmitted to an output shaft. Further embodiments relate to methods of converting linear motion to rotational motion by using a cylindrical cassette.

A connecting rod (24) has a modified end adapted to ensure that a lubricant film of sufficient thickness exists in an end bearing thereof when the connecting rod is placed in both tension and compression. The connecting rod includes an elongated body portion or shaft (40), a big end (42) defining a first coupling bore (44) at a first longitudinal end of the body portion (40), and a small end (46) defining a second coupling bore (48) at a second longitudinal end of the body portion (40). The small end (46) and the big end (42) each have a proximal side (50,52) nearest the shaft (40) and a distal side (54,56) furthest from the shaft (40). An opening (100) is formed in the shaft (40) adjacent the proximal side (52) for adjusting a stiffness of the proximal side (52).

A Rankine Expander System that converts low quality heat (heat usually at temperatures below 400 degrees Celsius) to electricity by using the properties of trans-critical CO.sub.2. The system is comprised of a compressor, an expander, three heat exchangers, and a permanent magnet alternator (PMA). It operates at pressures and temperatures that hold the CO.sub.2 above its critical point for the full cycle, and as such, attains high efficiencies even at low power. Under some conditions the efficiency can exceed 50%.

A linear actuator provided for moving a load includes an actuator housing having a tube and a housing bottom at one end of the tube and a housing head at another end of the tube. The linear actuator further includes a piston guided longitudinally in the actuator housing, and an actuator rod assembled with the piston and configured to protrude out of the actuator housing in a manner which is guided in the housing head. The linear actuator is configured such that reliability of operation is increased and damage of structural parts is largely avoided. The linear actuator achieves these results by virtue of the fact that there is at least one plastically deformable buffer element which can be supported on the housing head and can be deformed in the case of an impact of the piston. The buffer element is configured to convert kinetic energy into deformation work.

A linear actuator for moving a load includes a tubular actuator housing, which has an end-side housing bottom and an end-side housing head, a rotatably drivable threaded spindle which is mounted rotatably in the housing bottom of the actuator housing and extends in an interior of the actuator housing from the housing bottom in a direction of the housing head, a piston which comprises a spindle nut, which is in engagement with the threaded spindle, and is guided longitudinally in the actuator housing, and a hollow actuator rod which is assembled with the piston, into which actuator rod the threaded spindle dips, and which actuator rod protrudes out of the actuator housing on the housing head. The linear actuator is configured such that the actuator housing is filled with pressurized oil and gas, the oil and gas being situated in a single volume.