Abstract: A system is provided for automatically controlling the forward speed of travel of a combine in response to feeder and separator loading and to reduce speed in proportion to grain losses exceeding predetermined limits. A hydrostatic transmission between the combine engine and drive wheels is controlled by a control element actuated by a hydraulic cylinder which is controlled from a control valve actuated by solenoids connected to the output of a comparator circuit. Signals from separator and feed load sensors and also from grain loss monitors are combined and applied to one input of the comparator circuit and a signal from a feedback sensor coupled to the hydraulic cylinder is applied to the second input of the comparator. The load sensors include potentiometers coupled to spring-loaded idler pulleys which are engaged with drive belts for the separator and feeder drive shafts and the feedback sensor is also a potentiometer.

Abstract: A variable speed feed roll drive mechanism as provided for a forage harvester, the mechanism including a reversible hydrostatic transmission having its input shaft coupled with the chopper input shaft, the output of the transmission being coupled with the feed rolls. The hydrostatic transmission, having an infinitely variable range of output speeds provides the capability to infinitely vary the length of cut of crops passing through the chopper.