Patent ID: 8186473

Claim:
A hydrostatic ground drive control system for a work machine, comprising: a variable displacement fluid pump connected in fluid communication with a plurality of variable displacement fluid motors connected in rotatably driving relation to ground wheels of the machine, respectively; a programmable processor based controller in operative control of the displacement of the pump and the displacements of the motors, respectively; an operator controllable first input device connected to the controller and configured to be movable for outputting variable speed signals thereto, the first input device being movable through a range of forward positions for outputting forward speed signals to the controller, through a range of reverse positions for outputting reverse speed signals thereto, and to a neutral position for outputting a neutral position signal thereto; an operator controllable second input device connected to the controller and configured so as to be usable by an operator for inputting speed range command signals to the controller, including at least a first speed range command signal and a second speed range command signal; the controller being programmed to automatically simultaneously control the displacements of the pump and the motors in a substantially inverse relationship, including: a. responsive to changing speed signals for increasing a speed of rotation of the fluid motors, to automatically decrease the displacements of the motors and simultaneously increase the displacement of the pump; b. responsive to changing speed signals for decreasing a speed of rotation of the fluid motors, to automatically increase the displacements of the motors and simultaneously decrease the displacement of the pump; and c. responsive to a change in the speed range command signal, to automatically change the displacements of the motors at a predetermined rate to predetermined values, respectively, corresponding to the speed signal outputted by the first input device.