Abstract: A mechanism for transforming a translation movement into a rotation movement which is then followed by a translation movement comprising a first member which can be a control member slidable on a smooth shaft and constituted by a hollow cylinder coaxial with the shaft, and terminated by two planar symmetrical faces which are inclined with respect to the shaft, and a second member which can be a driven member and fixed to the shaft. The second member is constituted by two hollow cylinders coaxial with the shaft and of the same diameter as the control member. Each hollow cylinder terminates with a planar face having the same inclination with the shaft as the faces of the control member, the planar faces of the hollow cylinders being in contact with respective faces of the control member. The two planar faces of the driven member are angularly offset relative to one another.