Abstract: In a power driven roller conveyor having a plurality of rollers each connected to a shaft and a plurality of driven sprockets one of which is rotatably mounted on each of the shafts, a torque-responsive coupling is interposed between a driving member connected to each sprocket and a driven member connected to each shaft so that the rotation of any roller will be interrupted if the resistance to rotation exceeds a desired value, thereby permitting articles on the conveyor to be stopped and accumulated without undue scuffing and wear on the articles or on the rollers. The coupling consists of a wobble plate which is connected to the driven member for oscillating movement about a center coincident with the axis of the shaft and which has a surface disposed transversely to the axis of the shaft and facing the driving member. The wobble plate is spring urged toward the driving member.

Abstract: A conveyor consisting of a transfer bar provided with article supporting rollers, a stationary frame supporting the transfer bar, and driving means for reciprocating the transfer bar on forwarding and return movements, anti-backup dogs being mounted on the frame to prevent return article movement. An expandable and contractable section is provided at each end of the transfer bar, each section including a number of article supports which are slidably mounted on the frame so that their longitudinal spacing can be increased by a chain connection to the transfer bar and can be decreased through engagement by the transfer bar.