a mechanisms for temporarily attaching an object to a support , separating and ejecting the object , includes a receptacle adapted to be fixed to the support in which an ejector rod is slidably mounted . the ejector rod has a rear portion acted on by an ejection pressure and a front end bearing against a bearing surface near the center of mass of the object , at the end of an elongate recess into which the ejector rod extends to as far as the bearing surface . the body has an annular end portion which is joined to the body by a fragile coupling . the object is provided with a front central centering area at the bottom of the recess , into which extends , with at most a small clearance , the free end of the ejector rod and a rear end centering area situated near the mouth of the recess , into which extends , with small clearance , a rear centering male portion fastened to the body of the receptacle .