Copyright Goodheart-Willcox Co., Inc. 837 Chapter 24 ∣ Track Steering Systems Summary • Operators of twin track tractors must drive the tracks at different speeds or in different directions to steer the tractor. • The counter rotation steering method provides the tightest turning radius by propelling one track forward and the other track in reverse. • The brake steer method achieves a tight turning radius by braking the inside track. • The power steer method drives both tracks in the same direction but at different speeds. • The neutral steer method has the operator shift the inside track into neutral. • Dual-path hydrostatic-drive steering systems have a hydraulic pump and a hydraulic motor on each side of the tractor to provide propulsion and steering. • Steering clutch and brake systems require the steering clutches to be engaged and the steering brakes to be released in order to propel the machine in a straight line. A neutral steer is performed by releasing one steering clutch. A brake steer is performed by applying one steering brake. • Differential steering systems use two inputs, a hydraulic steering motor and a powershift transmission, to drive a planetary gear set that delivers power to the left and right final drives. • For differential-steered tractors, when the hydraulic steering motor is the only input, the tractor counter rotates. When the powershift transmission is the only input, the tractor drives forward or in reverse in a straight path. When both the hydraulic steering motor and the transmission are inputs, the tractor moves (propels) and steers. • Hydrostatic-driven, differential-steered, and Cat’s D7E dozers have better maneuverability as compared to steering clutch and brake dozers. • A two-speed planetary steering system uses a set of cluster gears and brakes on each track that allow the operator to place each track in one of the following positions: neutral, brake applied, low-speed, or high-speed. The system is not capable of counter rotation. • The term hydrostatic steering can describe traditional hydraulic steering for mobile equipment, the steering input for a differential-steered track-type tractor, or dual-path hydrostatic-propelled track-type tractors. • Some older track-type tractors have a steering system that requires the operator to manipulate multiple control levers instead of the joystick controls used in late-model machines. • Caterpillar’s D7E electric drive dozer uses an AC generator, power inverter, and two AC electric drive motors to propel and steer the tractor. • Case IH, John Deere, New Holland, and Versatile manufacture articulated tractors equipped with four track undercarriages that are similar to traditional four-wheel- drive articulated tractors.