Air-conditioning device for a railway vehicle having at least two carriages

The air conditioning device (10) comprising means (22) for emitting a flow of air-conditioned air and at least one circulation circuit (28) intended to equip a car, comprising an air inlet (32) through which passes an incoming air flow from the emission means (22); at least one air distribution duct (34) towards a room, extending between an upstream end (34A) and a downstream end (34B), both intended to be arranged in said car; a duct (35) for transferring air-conditioned air towards another adjacent air circulation circuit (36), said other circulation circuit (36) equipping another car adjacent to the first; and means (40) for distributing air-conditioned air from the air inlet (32), distributing the incoming air flow between the distribution ducts (34) and transfer duct (35).