The invention relates to a detent mechanism (18) for controlling translation between two components (2, 7) in a longitudinal direction (P, D), the detent mechanism (18) comprising at least one clip (7.12, 2.6) on one of the components (2, 7) arranged to be in a ramped engagement with a recess in the other one of the components (7, 2) in an initial state in such a manner that translation between the components (2, 7) is constrained and that application of a translative force between the components (2, 7) in one longitudinal direction (P, D) with the clip (7.12, 2.6) engaged with the recess deflects the clip (7.12, 2.6) out of the recess when a predetermined value of the translative force, at least depending on the resilience of the clip (7.12, 2.6), is overcome so as to allow translation between the components (2, 7).本発明は縦方向（Ｐ、Ｄ）への二つの部材（２、７）間の並進運動を制御するための戻り止め機構（１８）に関し、部材（２、７）間の並進運動が制約されるように、そして部材（２、７）間の並進運動を可能にするべく、少なくともクリップ（７．１２、２．６）の弾力性に依存する並進運動力が所定の値を越えたとき、凹部と係合されたクリップ（７．１２、２．６）で、部材（２、７）間の一方の縦方向（Ｐ、Ｄ）に並進運動力をかけることが、クリップ（７．１２、２．６）を凹部から外に偏向させるように、初期状態において、一方の部材（７、２）の凹部とランプ係合にあるように配置された他方の部材（２、７）上に少なくとも一つのクリップ（７．１２、２．６）を含んでなる。【選択図】 図２０
