Patent attributes
A propulsion system is for a road milling machine with a rotatable cutter drum (3). The system includes four crawler assemblies (12) movably coupled with the mainframe so as to define front and rear, and left and right, pairs of crawler assemblies. Four steering actuators (14) are each coupled with a separate crawler assembly and each angularly displaces the crawler about a vertical axis (12a). A first pump (16A) is fluidly coupled with the left pair of crawlers and a second pump (16B) is fluidly coupled with the right pair of crawlers. A control (20) is configured to selectively operate the four actuators in a plurality of different steering modes, one steering mode being a circle steer mode, and to operate the two pumps such that one of the left and right pairs of crawlers are drivable by the first pump in one direction while the other pair of crawlers are drivable in an opposing direction.
