Series Hydraulic Motor System for Driving Air Moving Fans on an Agricultural Harvesting Combine

In a harvesting combine having a forward power processing unit (PPU) powered by an internal combustion engine and having a forward set of wheel assemblies and a rear grain cart connected by an articulating joint assembly, a rear grain cart for storage of harvested grain, a forward operator cab, a cleaning fan assembly located about the forward bottom of the PPU, and rotor, concaves, and grates assembly therein for threshing of grain from material other than grain (MOG), and shaken main sieves assemblies for separating product grain and tailings composed primarily of MOG, a charge fan assembly located behind the forward operator cab and drawing air from about the top of the PPU and directing a portion of an air flow from the charge fan assembly downwardly into the cleaning fan assembly, and bonus sieves assemblies located in the outer rear of each side of the PPU for accepting the tailings from the concaves and grates assemblies and the main sieves assemblies for additional separation of grain from MOG, wherein the cleaning fan assembly is powered by a cleaning fan hydraulic motor assembly, the charge fan assembly is powered by a charge fan assembly hydraulic motor assembly, each bonus sieves assemblies powered by a hydraulic motor assembly, the internal combustion engine powering a hydraulic pump fed by a tank of hydraulic fluid, the improved series hydraulic fluid motor circuit which comprises:

• a hydraulic line running from the pump to the cleaning fan hydraulic motor assembly, a hydraulic line running from the cleaning fan hydraulic motor assembly to the charge fan hydraulic motor assembly, a pair of equal hydraulic lines running from the charge fan hydraulic motor assembly to each of the bonus sieves hydraulic motor assemblies, and hydraulic return lines from each of the bonus sieves hydraulic motor assemblies to the hydraulic fluid tank.