Abstract: Conveyors containing powered rollers arranged in zones, each of which zones may be independently controlled. Such conveyors are particularly useful in transitioning object flow from a constant speed conveyor such as in a plant or warehouse, to manual offloading operations which tends to be more intermittent in nature. The independently controlled zones automatically activate and deactivate in a manner that allows objects to accumulate in a compact fashion on the conveyor when offloading operations stop, but once again to space themselves apart from one another as offloading operations resume and flow once again reaches steady state. This increased spacing during steady state flow allows the conveyor to begin absorbing objects in the accumulation mode if and when offloading stops again. Among other beneficial effects is an ergonomic one: Workers are freed from the stress of knowing that objects flowing on the conveyor will simply be propelled off the end if they take a momentary break.

Abstract: Chain driven expandable powered conveyors utilizing lazy tong structures. A first embodiment of such conveyors employs elongated rollers which are connected to sprockets driven by one or more drive chains. The chains follow a tortuous path through the conveyor structure allowing efficient and effective transmission of power from a power source to the sprockets and elongated rollers regardless of the extent to which the conveyor is expanded or contracted. A second embodiment, which also employs elongated rollers, includes sprockets powered by a chain that in turn apply power to elongated rollers using drive belts. This embodiment avoids exposure of drive chain at the surface of the conveyor, allows accumulation of product on the conveyor and features other advantages. A third embodiment employs skate wheels rather than elongated rollers. A drive chain applies power to drive sprockets on the surface of the conveyor which propel product on the conveyor.