The subject matter of this specification can be embodied in, among other things, a fluid actuator including a housing defining a first chamber having a first cavity and a first open end, a first piston assembly including a tubular first piston defining a second chamber having a second cavity and a second open end, disposed in said first housing for reciprocal movement in the first chamber through the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a second piston assembly having an second piston disposed in said first piston assembly for reciprocal movement in the second chamber through the second open end, wherein a second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a first end effector.

A fluid powered rotary actuator having a first member which is pivotally connected to a second member and which is includes at least one toroidal shaped spear or piston which acts within a correspondingly shaped toroidal shaped cylinder to move the first member relative to the second member. The or each toroidal shaped spear or piston and cylinder assembly includes seals mounted within a seal carrier and the configuration allows movement of the seals relative to the or each cylinder. This configuration allows the seals to continue to provide a leak resistant hydraulic seal between each toroidal shaped spear or piston and its associated cylinder even in cases where the toroidal shaped spears or pistons deflect relative to their associated cylinders. The cylinders are also mounted to the first or second members in a manner designed to reduce the chance of tensile cracking due to deflection of the cylinders.

Devices and systems for producing rotational actuation are described. More specifically, hydraulic and pneumatic actuators that can produce and control rotational or joint-like motion are described. An actuator may include a torus shaped cylinder configured to enable rotation of the actuator. An actuator may further include both a piston configured to rotate from a first end of the torus shaped cylinder to a second end of the torus shaped cylinder and a piston rod coupled to the piston.

A shaft extending along a longitudinal axis has fluid channels that increase and decrease pressure in chambers formed between the interior ends of curved pistons and adjacent closed ends of curved chambers within which the pistons reciprocate as the chamber pressure increases and decreases. The chambers and pistons are in separate cylinder block segments extending outward from opposing sides of the shaft. Each segment may have two sides extending along radial planes and joined by a curved outer surface. Pistons may be provided in pairs and have an interior piston end of each piston in a different cavity in different segments. Exterior ends of each piston in a pair of pistons are connected to a piston connector that extends inwardly from a housing so the housing rotates with the pistons.

A rotary actuator includes a housing, a rotor assembly rotatably journaled in said housing and including a rotary output shaft, a central actuation assembly including a central mounting point formed in an external surface of the rotary output shaft, said central mounting point proximal to the longitudinal midpoint of the rotary output shaft, a mounting assembly adapted for attachment to an external mounting connector of a mounting surface of an aircraft structural member, and an actuation arm removably attached at a proximal end to the central mounting point, said actuation arm adapted at a distal end for attachment to an external mounting feature of an aircraft assembly to be actuated.

Devices and systems for producing rotational actuation are described. More specifically, hydraulic and pneumatic actuators that can produce and control rotational or joint-like motion are described. An actuator may be configured to allow parallel coupling of multiple actuators, and thus increase the range of rotation of the actuators when considered collectively.

A shaft extending along a longitudinal axis has fluid channels that increase and decrease pressure in chambers formed between the interior ends of curved pistons and adjacent closed ends of curved chambers within which the pistons reciprocate as the chamber pressure increases and decreases. The chambers and pistons are in separate cylinder block segments extending outward from opposing sides of the shaft. Each segment may have two sides extending along radial planes and joined by a curved outer surface. Pistons may be provided in pairs and have an interior piston end of each piston in a different cavity in different segments. Exterior ends of each piston in a pair of pistons are connected to a piston connector that extends inwardly from a housing so the housing rotates with the pistons.

The subject matter of this specification can be embodied in, among other things, a rotary actuator that includes a housing defining an arcuate chamber comprising a cavity, a rotor arm configured for rotary movement, an arcuate-shaped first piston disposed in said housing for reciprocal movement in the arcuate chamber, where a seal, the cavity, and the piston define a pressure chamber that includes part or all of the arcuate chamber, and a portion of the piston contacts the rotor arm, and a rotor assembly rotatably surrounding said housing and having a rotary output tube about the axis, wherein the rotor arm extends radially outward to the rotary output tube and the rotor arm is coupled to the rotary output tube.

The subject matter of this specification can be embodied in, among other things, a multi-axis rotary actuator that includes a first rotary piston actuator configured to controllably actuate a first pivotal joint between a first linkage to a second linkage about a first axis, and a second rotary piston actuator configured to controllably actuate a second pivotal joint connecting the second linkage to a third linkage about a second axis.

An engine includes a housing and a combustion assembly. The combustion assembly includes an annular bore and a combustion piston assembly disposed within the annular bore. The combustion piston assembly includes a set of pistons, a first sealing ring connected to each piston and a second sealing ring connected to each piston. The second sealing ring is configured to provide selective access between the annular bore and at least one fluid conduit carried by the engine. The engine includes at least one valve configured to move between a first position within the annular bore to allow the combustion piston assembly to travel within the annular bore from a first location proximate to the at least one valve to a second location distal to the at least one valve and a second position within the annular bore to define a combustion chamber.