A lead screw (5), a lead screw nut and a drive member are aligned with an axis (4). A coupling between the lead screw and the lead screw nut allows a helical movement of the lead screw. The drive member is rotationally locked with the lead screw nut. The lead screw is coupled with the drive member to generate a helical movement of the lead screw when the drive member is moved in one axial direction. The coupling is overridden when the drive member is moved in the opposite axial direction. Spline features (25) are arranged on the lead screw in a row (20) parallel to the axis with alternatingly small and large gaps between succeeding spline features. A stop feature of the drive member has a dimension in the direction of the axis which is larger than the small gaps and at most as large as the large gaps.一導螺桿(5)、一導螺桿螺帽以及一驅動構件對齊於一軸線(4)。導螺桿與導螺桿螺帽間之聯結允許導螺桿進行一螺旋運動。驅動構件係以導螺桿螺帽以旋轉方式鎖上。導螺桿與驅動構件聯結,於是當驅動構件進行一軸向方向運動時,導螺桿能夠產生一旋轉運動。當驅動構件於相反的軸向方向中運動時,聯結則會失效。多個齒條特製件(25)平行於軸線而呈一列(20)地設置在導螺桿上,且後繼的齒條特製件之間會有交替的小間隙與大間隙。驅動構件的一止動特製件在軸線方向的大小係大於小間隙,且至多與大間隙一般大。4...軸線5...導螺桿6...螺紋15...彈性引導特製件16...另一螺紋20...含多個齒條特製件之列25...齒條特製件
