Receiver mounted in an ambulance comprising: ▪ a base with two grooves parallel to each other; ▪ a shuttle moving in translation over the said base; and ▪ an anchoring device (20a-20c) moved by the said shuttle, the said anchoring device (20a-20c) comprising: • a plate (22a-22b) moving in translation over the said receiver to allow the automatic movement of a carriage; with the plate (22a-22b) moved in translation by two belts driven by the said shuttle to obtain demultiplication between the movement of the said shuttle and the movement of the said plate (22a-22b); and • at least one hook (30a-30c) comprising a housing (31a-31b) designed to receive a carriage bar; and • a bolt (32a-32b) moving between two positions: ∘ a closed position in which the bolt (32a-32b) is placed in front of the said housing (31a-31b); and ∘ an open position in which the bolt (32a-32b) is no longer placed in front of the said housing (31a-31b); the said bolt (32a-32b) being moved by a connecting rod (34a-34c) of which the first end is connected to the bolt (32a-32b) and the second end is connected to a dowel (41a-41c) designed to work together with at least one stop placed in the path of the said plate (22a-22b) so that the movement of the plate (22a-22b) causes the said dowel (41a-41c) to work together with the said stop to control the opening or closing of the said bolt (32a-32b). ▪ a base with two grooves parallel to each other; ▪ a shuttle moving in translation over the said base; and ▪ an anchoring device (20a-20c) moved by the said shuttle, the said anchoring device (20a-20c) comprising: • a plate (22a-22b) moving in translation over the said receiver to allow the automatic movement of a carriage; with the plate (22a-22b) moved in translation by two belts driven by the said shuttle to obtain demultiplication between the movement of the said shuttle and the movement of the said plate (22a-22b); and • at least one hook (30a-30c) comprising a housing (31a-31b) designed to receive a carriage bar; and • a bolt (32a-32b) moving between two positions: ∘ a closed position in which the bolt (32a-32b) is placed in front of the said housing (31a-31b); and ∘ an open position in which the bolt (32a-32b) is no longer placed in front of the said housing (31a-31b); the said bolt (32a-32b) being moved by a connecting rod (34a-34c) of which the first end is connected to the bolt (32a-32b) and the second end is connected to a dowel (41a-41c) designed to work together with at least one stop placed in the path of the said plate (22a-22b) so that the movement of the plate (22a-22b) causes the said dowel (41a-41c) to work together with the said stop to control the opening or closing of the said bolt (32a-32b). • a plate (22a-22b) moving in translation over the said receiver to allow the automatic movement of a carriage; with the plate (22a-22b) moved in translation by two belts driven by the said shuttle to obtain demultiplication between the movement of the said shuttle and the movement of the said plate (22a-22b); and • at least one hook (30a-30c) comprising a housing (31a-31b) designed to receive a carriage bar; and • a bolt (32a-32b) moving between two positions: ∘ a closed position in which the bolt (32a-32b) is placed in front of the said housing (31a-31b); and ∘ an open position in which the bolt (32a-32b) is no longer placed in front of the said housing (31a-31b); ∘ a closed position in which the bolt (32a-32b) is placed in front of the said housing (31a-31b); and ∘ an open position in which the bolt (32a-32b) is no longer placed in front of the said housing (31a-31b);