A device for an overhead conveyor system of the type where a plurality of carriages (7) by contracting a rotating drive shaft (5) are propellable along a rail (2). The device comprises an operating arm (28) arranged in connection with a first carriage (7b) and adapted to actuate, by turning about an axis of rotation (26), a power transmission element (24) to disconnect the carriage from contact with the drive shaft, and an angled supporting surface (20) arranged in connection with a second carriage (7a). One end of the operating arm (28) is further adapted, when said carriages (7a, 7b) are moved towards each other, to contact said angled supporting surface (20) and be moved along the same, so that the operating arm (28) thus performs a turning motion and disconnects said first carriage (7b). According to the invention, the drive of the carriage will thus be interrupted as soon as its operating arm is contacted with the supporting surface of an anteriorly situated carriage. In this manner, carriages can be buffered.
