Abstract: The invention relates to an actuator for actuating a moving member, said actuator essentially comprising a screw and at least two nuts engaged on the screw, relative movement between the screw and the nuts generating said actuation, said actuator further comprising a pin through which an electrical link passes, a force-transmitting element placed in the path of the force between the screw and the moving member via one of the nuts, and a mechanical extension of said force-transmitting element that extends to the vicinity of the other nut, the pin passing both through the mechanical extension and through an element coupled to the other nut so that any abnormal shift in the force-transmitting element relative to the screw results in shear between its mechanical extension and the element coupled to the other nut, causing the pin to break and causing the electrical link to be broken.

Abstract: The invention relates to an actuator for actuating a moving member, said actuator essentially comprising a screw and at least two nuts engaged on the screw, relative movement between the screw and the nuts generating said actuation, said actuator further comprising a pin through which an electrical link passes, a force-transmitting element placed in the path of the force between the screw and the moving member via one of the nuts, and a mechanical extension of said force-transmitting element that extends to the vicinity of the other nut, the pin passing both through the mechanical extension and through an element coupled to the other nut so that any abnormal shift in the force-transmitting element relative to the screw results in shear between its mechanical extension and the element coupled to the other nut, causing the pin to break and causing the electrical link to be broken.

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 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.