handle 12 is opened the operator first unlocks the second locking system 8 and then unlocks the first locking system 7 as above the locking of this device is obtained by the inverse succession of the aforementioned steps a third embodiment is illustrated in fig2 to 29 this third embodiment corresponds to the second locking device 6 the position of which is illustrated in fig1 for easier understanding the elements have been designated by the same reference numbers as before the first locking system 7 is shown in fig2 the latter comprises a body 40 that is fixed relative to the movable element 1 and is fitted with a bolt 41 mounted so as to be displaceable in translation on the body capable of being displaced between a first locked position shown in fig2 in which the bolt 41 traverses a slot 42 designed for the insertion of the corresponding retention member 10 and an unlocked position shown in fig2 in which the bolt 41 is retracted relative to the slot 42 the translation of the bolt 41 is actuated by the user via a handle 12 shown in fig1 connected to the bolt 41 by a rod 43 the second locking device 6 also comprises a movement transformation member 44 mounted on the first locking system 7 making it possible to transform the translation movement of the handle 12 and of the bolt into a translation.