| 摘要 |
A screw actuator comprises a rotatable input member (30) and a non-rotatable primary output member (36), wherein the input member (30) is provided with a screw thread formation (38) within which a plurality of spherical members (34) are received to provide a ball screw coupling between the input member (30) and the primary output member (36). The actuator includes a secondary output arrangement (42) having first and second screw threaded parts (46, 48) in screw threaded engagement with the input member (30) to provide a screw thread coupling between the input member (30) and the secondary output arrangement (42). The first and second screw threaded parts (46, 48) 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 (46, 48) serves to lock the first and second screw threaded parts (46, 48) onto the input member (30), thereby to stall the actuator. <IMAGE> |
