In an overhead-rail materials-conveyance system including an endless drive chain juxtaposed to an endless rail for driving hanger-type carriers suspended therefrom by means of wheels, a coupling assembly for carrier entrainment comprises a plurality of jaws pivotably mounted on the drive chain for swinging about respective axes parallel to the transport direction. The jaws are each provided with beveled edges for cammingly engaging coupling and uncoupling heads projecting vertically from front and back ends, respectively, of the carriers; the jaws have recesses of a breadth greater than the width of the coupling heads and less than the width of the uncoupling heads for forming locked engagements with only the coupling heads upon spreading of the jaws thereby. Upon the approach of a train of carriers towards a standing carrier, the uncoupling head thereof spreads the jaws entraining the first carrier in the train, thereby releasing this carrier. The uncoupling jaws then pass through the spread jaws which are subsequently opened by and locked to the coupling head of the standing carrier, whereby the same becomes entrained as a new first carrier.
