An actuation unit includes an actuating arm pivotable between an open and closed position; a pneumatic cylinder comprising a stem movable linearly along a cylinder axis and configured to control pivoting of the actuating arm; and a closing device that includes a braking unit configured to brake movement of the actuating arm having a surface portion configured to come into contact with at least one braking assembly. The braking assembly is locked against rotation and axially movable between a non-braking and braking configuration. The surface portion is in a non-orthogonal arrangement with respect to the cylinder axis and the braking assembly includes a plurality of rollers retained in the braking assembly with clearance at least with respect to a radial movement thereof, the rollers being able to assume a first radial configuration not in contact with the surface portion and a second radial configuration in contact with the surface portion.

The subject matter of this specification can be embodied in, among other things, a thrust reverser synchronization shaft lock system includes a rotatable shaft comprising at least one radial prong extending radially from the shaft, a hydraulic lock assembly that includes a housing, a piston head having a lock recess, a piston rod extending radially away from the shaft and configured to be urged by the piston head to move the first piston rod end out of engagement with the radial prong to selectably permit rotation of the shaft, and a bias member configured to urge the first piston rod end into engagement with the radial prong, and an electric lock assembly that includes a lock pin and an electric actuator configured to controllably extend and retract the lock pin in and out of engagement with the lock recess.

Disclosed is an aircraft piston assembly, having: a piston housing fluid port formed in a piston housing; a piston shaft, disposed within the piston housing, configured for translation in either forward or aft directions when fluid is respectively supplied to or removed from the piston housing; a screw shaft, disposed within the piston housing, that includes a first gear that rotates without translation while the piston shaft translates; and a slider, disposed within the piston housing, that includes a second gear, and that is configured for translation without rotation, wherein: the slider moves between a first position where the first gear and the second gear are separated from one another to allow the piston shaft to translate and a second position where the second gear surrounds the first gear so that the first and second gears are engaged with one another and the piston shaft is prevented from translating.

Inerters with friction disk assemblies, and aircraft hydraulic systems and aircraft including the same. An inerter comprises an inerter housing containing an inerter fluid, a threaded shaft extending within the inerter housing and fixed relative to the first terminal, and an inerter rod extending at least partially within the inerter housing and fixed relative to the second terminal. The inerter further includes a friction disk assembly that, together with the inerter fluid, is configured to damp a motion of the second terminal relative to the first terminal. The friction disk assembly includes a fixed portion and a rotating portion, and is configured such that rotation of the rotating portion generates a frictional torque that opposes the rotation of the rotating portion. In some examples, the inerter is a component of a hydraulic actuator, an aircraft hydraulic system including the hydraulic actuator, and/or an aircraft including the aircraft hydraulic system.

The subject matter of this specification can be embodied in, among other things, a thrust reverser synchronization shaft lock system includes a rotatable shaft comprising at least one radial prong extending radially from the shaft, a hydraulic lock assembly that includes a housing, a piston head having a lock recess, a piston rod extending radially away from the shaft and configured to be urged by the piston head to move the first piston rod end out of engagement with the radial prong to selectably permit rotation of the shaft, and a bias member configured to urge the first piston rod end into engagement with the radial prong, and an electric lock assembly that includes a lock pin and an electric actuator configured to controllably extend and retract the lock pin in and out of engagement with the lock recess.

A track tensioning system for adjusting tension in a vehicle track, comprising a track tensioner comprising a hydraulic cylinder and a piston assembly slidably moveable within the cylinder and dividing the cylinder into a first and second chamber each in selective fluid communication with a pressurised hydraulic fluid source and reservoir, such that supply or withdrawal of hydraulic fluid to or from the chambers causes the piston assembly to move within the cylinder in either extension, increasing track tension, or retraction, decreasing track tension, further comprising a locking system capable of mechanically locking the position of the piston assembly with respect to the hydraulic cylinder, wherein the locking system is switchable between an engaged mode, where it prevents movement of the piston, thereby maintaining tension in the vehicle track, and a disengaged mode, where it allows movement of the piston, thereby allowing tension in the vehicle track to be adjusted.

Inerters with friction disk assemblies, and aircraft hydraulic systems and aircraft including the same. An inerter comprises an inerter housing containing an inerter fluid, a threaded shaft extending within the inerter housing and fixed relative to the first terminal, and an inerter rod extending at least partially within the inerter housing and fixed relative to the second terminal. The inerter further includes a friction disk assembly that, together with the inerter fluid, is configured to damp a motion of the second terminal relative to the first terminal. The friction disk assembly includes a fixed portion and a rotating portion, and is configured such that rotation of the rotating portion generates a frictional torque that opposes the rotation of the rotating portion. In some examples, the inerter is a component of a hydraulic actuator, an aircraft hydraulic system including the hydraulic actuator, and/or an aircraft including the aircraft hydraulic system.

Disclosed is an aircraft piston assembly, having: a piston housing fluid port formed in a piston housing; a piston shaft, disposed within the piston housing, configured for translation in either forward or aft directions when fluid is respectively supplied to or removed from the piston housing; a screw shaft, disposed within the piston housing, that includes a first gear that rotates without translation while the piston shaft translates; and a slider, disposed within the piston housing, that includes a second gear, and that is configured for translation without rotation, wherein: the slider moves between a first position where the first gear and the second gear are separated from one another to allow the piston shaft to translate and a second position where the second gear surrounds the first gear so that the first and second gears are engaged with one another and the piston shaft is prevented from translating.

An actuation unit includes an actuating arm pivotable between an open and closed position; a pneumatic cylinder comprising a stem movable linearly along a cylinder axis and configured to control pivoting of the actuating arm; and a closing device that includes a braking unit configured to brake movement of the actuating arm having a surface portion configured to come into contact with at least one braking assembly. The braking assembly is locked against rotation and axially movable between a non-braking and braking configuration. The surface portion is in a non-orthogonal arrangement with respect to the cylinder axis and the braking assembly includes a plurality of rollers retained in the braking assembly with clearance at least with respect to a radial movement thereof, the rollers being able to assume a first radial configuration not in contact with the surface portion and a second radial configuration in contact with the surface portion.

A system, including a magnetorheological (MR) fluid locking system, including a housing, a piston disposed in the housing, wherein the piston is configured to move axially within the housing, an MR fluid disposed in the housing, an MR fluid pump fluidly coupled to the housing, wherein the MR fluid pump is configured to pump the MR fluid into the housing, and an electromagnet configured to magnetize the MR fluid to control axial movement of the piston.