US Patent 7877976 Spring flotation for center deck of draper header

A harvesting machine includes a harvesting header with a header frame, a cutterbar assembly attached to the header frame along the length thereof and configured to cut a crop, and a draper assembly positioned behind the cutterbar assembly. The draper assembly includes a center draper that delivers crop material to a feeder house of the harvesting machine and oppositely spaced side drapers that deliver crop material to the center draper. The center draper includes a draper frame swingably supported on the header frame at a pivot to project forwardly therefrom and a draper belt supported on the draper frame to present a rearwardly moving run for conveying the crop rearwardly. The center draper includes a counterbalance mechanism coupled between the header and draper frames to counteract the weight of the center draper about the pivot so as to reduce the load of the center draper on the cutterbar assembly.