Patent ID: 8704620

Claim:
A linear actuator comprising: a drive arm and an extension arm each extending along a common drive axis; the extension arm being at least partially received in a housing, the housing allowing displacement of the extension arm along the common drive axis but preventing rotation of the extension arm around the common drive axis; one of the arms having a plurality of resiliently deformable fingers extending beyond the end of the one of the arms towards the other one of the arms, at least one of the plurality of fingers having a thread on an inner face thereof; the other arm having a thread, at least part of the thread being received between the plurality of fingers; the thread of each of the arms including a ridge defined between two edges and a groove defined by sides extending from the two edges; the plurality of fingers being adapted to urge the thread of each of the arms into interengagement such that rotation of the drive arm about the common drive axis displaces the extension arm along the common drive axis; wherein the thread of each of the arms is arranged such that when the ridge of one thread is received in the groove of the other thread, the sides of the one thread abut the two edges of a mouth of the groove of the other thread; and wherein the angle between faces of the ridges at the points of abutment is larger than the angle between faces of the groove at the points of abutment.