Patent ID: 7942604
Filing Date: 2011-05-17
Classification: B62D,E01C

Abstract:
1. A propulsion system for a road milling machine, the milling machine including a mainframe with front and rear ends, a center, and a centerline extending between the two ends and through the center, and a rotatable cutter drum coupled with the mainframe, the system comprising: four crawler assemblies each movably coupled with the mainframe so as to define front and rear pairs of crawler assemblies, each crawler assembly having a vertical axis, being angularly displaceable about the vertical axis, and including a frame with a centerline, a plurality of wheels rotatably mounted to the frame, an endless track disposed about the wheels, and a motor configured to rotate at least one wheel in opposing angular directions so as to drive the endless track in opposing angular directions about the plurality of wheels and generally along the frame centerline; four steering actuators each operatively coupled with a separate one of the four crawler assemblies and configured to angularly displace the coupled crawler assembly about the crawler vertical axis independently of the others of the four crawler assemblies; and a control operatively coupled with each one of the four steering actuators and configured to selectively and independently operate the four actuators in a plurality of different steering modes, one steering mode being a circle steer mode such that one of the front pair of crawler assemblies angularly displaces in a first direction about the crawler vertical axis, the other one of the front pair of crawler assemblies independently angularly displaces in a second, opposing direction about the crawler vertical axis, one of the rear pair of crawler assemblies angularly displaces in the first direction about the crawler axis, and the other one of the rear pair of crawler assemblies independently angularly displaces in the second direction about the crawler axis wherein the control includes a microprocessor electrically connected with each one of the four steering actuators and a program installed within the microprocessor, the program being configured to selectively and independently operate the four steering actuators in each one of a plurality of different steering modes.