Abstract: A screw actuator comprises a rotatable input member and a non-rotatable primary output member, wherein the input member is provided with a screw thread formation within which a plurality of spherical members are received to provide a ball screw coupling between the input member and the primary output member. The actuator includes a secondary output arrangement having first and second screw threaded parts in screw treaded engagement with the input member to provide a screw thread coupling between the input member and the secondary output arrangement. The first and second screw threaded parts are axially movable relative to one another, whereby, in the event that the ball screw coupling fails, relative axial movement of the first and second screw threaded parts serves to lock the first and second screw threaded parts onto the input member, thereby to stall the actuator.

Abstract: A no-back device for an actuator having a screw shaft extending along an axis and a brake element fixed for rotation with the shaft and extending laterally of the axis, the no-back device comprising a rotary ratchet member and a rotary friction member mounted for limited axial movement within a recess defined by a housing, and defining at least one path for passing fluid through the recess, the no-back device further comprising peripherally extending diversion means disposed between an outer periphery of the friction member and an inwardly facing peripheral surface of the housing whereby, in use, fluid passing through the recess is diverted away from the inwardly facing peripheral surface of the housing and across a laterally extending surface of the friction member.

Abstract: A no-back device for an actuator having a screw shaft extending along an axis and a brake element fixed for rotation with the shaft and extending laterally of the axis, the no-back device comprising a rotary ratchet member and a rotary friction member mounted for limited axial movement within a recess defined by a housing, and defining at least one path for passing fluid through the recess, the no-back device further comprising peripherally extending diversion means disposed between an outer periphery of the friction member and an inwardly facing peripheral surface of the housing whereby, in use, fluid passing through the recess is diverted away from the inwardly facing peripheral surface of the housing and across a laterally extending surface of the friction member.

Abstract: A screw actuator comprises a rotatable input member and a non-rotatable primary output member, wherein the input member is provided with a screw thread formation within which a plurality of spherical members are received to provide a ball screw coupling between the input member and the primary output member. The actuator includes a secondary output arrangement having first and second screw threaded parts in screw treaded engagement with the input member to provide a screw thread coupling between the input member and the secondary output arrangement. The first and second screw threaded parts are axially movable relative to one another, whereby, in the event that the ball screw coupling fails, relative axial movement of the first and second screw threaded parts serves to lock the first and second screw threaded parts onto the input member, thereby to stall the actuator.

Abstract: A no-back device for an actuator having a screw shaft extending along an axis and a brake element fixed for rotation with the shaft and extending laterally of the axis, the no-back device comprising a rotary ratchet member and a rotary friction member mounted for limited axial movement within a recess defined by a housing, and defining at least one path for passing fluid through the recess, the no-back device further comprising peripherally extending diversion means disposed between an outer periphery of the friction member and an inwardly facing peripheral surface of the housing whereby, in use, fluid passing through the recess is diverted away from the inwardly facing peripheral surface of the housing and across a laterally extending surface of the friction member.

Abstract: A thrust reversal system for a jet aircraft engine, comprising thrust reverser buckets movable between a stowed and a deployed position, an air motor operable under pilot's control to impart movement to the buckets, a piston movable in a cylinder having restricted outlet orifices for automatically decelerating the motor when the buckets approach both the stowed and the deployed position, a locking mechanism for locking the buckets in the stowed position and a flow control valve for controlling the direction of flow of operating air to the motor, the flow control valve, upon selection of deploy, initially occupying a position corresponding to movement of the motor in the direction to stow the buckets and, after release of the locking mechanism, moving to its alternative position to enable the motor to move the buckets to the deployed position.