rotating steering wheel 408 signals 402 404 also are fed to left articulation cylinder 46 and right articulation cylinder 48 with lines 410 and 412 supplying the necessary interconnection between cylinders 46 48 and lines 410 412 such interconnection is the primary steering mechanism for articulated combine 10 the operator indicates the desired speed of combine 10 through lever 414 which is connected by line 416 to front axle pump 418 which drives front motor drive 420 lines 422 and 424 interconnect pump 418 and motor 420 with lines 426 and 428 providing two more inputs to controller 400 potentiometer 430 provides a reference signal via line 432 to controller 400 left track pump 434 powers left track motor 436 via lines 438 and 440 from which signals 442 and 444 are sent to controller 400 line 446 provides yet another input to controller 400 from left track motor 436 right track pump 448 powers right track motor 450 via lines 452 and 454 from which signals 456 and 458 are sent to controller 400 line 460 provides yet another input to controller 400 from right track motor 436 finally controller 400 communicates with left track pump 434 via line 462 and with right track pump 448 via line 464 all equipment is conventional in nature and design one condition that requires special attention for a tracked articulated.