Copyright Goodheart-Willcox Co., Inc. Heavy Equipment Power Trains and Systems 832 The original two-speed planetary steering system design used steering levers as controls. The position of the steering levers determines the following factors: • If the high-speed disc is held (high). • If the low-speed disc is held (low). • If no speed discs are held (neutral). • If no speed discs are held and the output shaft is held (brake steer). Modern machines equipped with this system have a left-hand joystick that controls the tractor’s propulsion and steering. The two-speed planetary steer- ing system is not capable of counter rotation. When one track steers in high speed and the other in low speed, the machine is driving with two powered tracks, as opposed to a steering clutch and brake tractor that must remove power from one track in order to steer. The dozer can also be steered by placing a track in neutral or applying the steering brake. Independent-Geared Lever-Operated Track Steering Systems Older Case 1150B-E and 1450B track loaders and dozers use five separate control levers to control the machine speed, direction, and steering. See Figure 24-25. The tractors also have independent service brake pedals. The tractor’s propulsion and steering is achieved through the use of powershift-type clutches via countershafts and planetary gear sets, steering brakes, and bevel gears sets. Figure 24-26 shows the order of power flow through the track steering system. Goodheart-Willcox Publisher Figure 24-25. This diagram of Case 1150B-E and 1450B track loader and dozer controls shows how the five individual track control levers are used to operate the tractor’s forward and reverse propulsion, tractor speed, and steering. H N L H N L H L F N R F N R Bevel ring gear Bevel pinion gear Low-speed disc High-speed disc Steering brake disc Cluster gear Final drive pinion gear Goodheart-Willcox Publisher Figure 24-24. In a two-speed planetary steering system, the machine’s transmission powers the ring and pinion bevel gear set. The low-speed disc holds the low-speed sun gear. The high-speed disc holds the high-speed sun gear. The steering brake disc holds the track stationary. Both the right and left track drives each contain a two- speed gearing system, both driven by the bevel pinion gear. Right track control levers Left track control levers