Differential drive spiral accumulator apparatus

A spiral accumulator apparatus is disclosed for controlling the flow of articles. The apparatus includes an infeed conveyor driven in a first direction to convey articles therealong in the first direction along a first path that is at least partially curved, and an outfeed conveyor driven in an opposite direction to convey articles therealong in the opposite direction along a second path that is at least partially curved. The infeed and outfeed conveyors are spaced apart and generally parallel along at least a portion of the first and second paths so as to define a space therebetween. A movable transport member is disposed generally across and movable along the space, and an article transfer member is carried by the transport member and operably disposed between the infeed and outfeed conveyors to transfer articles between the infeed conveyor and the outfeed conveyor. A transport member mover is connected to the transport member, the transport member mover including an endless loop movable when a relative speed difference exists between the infeed and outfeed conveyors thereby causing the transport member to travel in the direction of the faster of the infeed and outfeed conveyors. Various options and modifications are possible, including use of a differential drive mechanism of mechanical, gear-based, or sensor and controller based designs.