Copyright Goodheart-Willcox Co., Inc. 815 Chapter 24 Track Steering Systems Objectives After studying this chapter, you will be able to: ✓ Describe the types of twin track turning radiuses. ✓ Explain the advantages and disadvantages of hydrostatic-propelled track-type tractors. ✓ Explain the operation of steering clutch and brake systems. ✓ Explain the operation of differential steering systems. ✓ Define how the term hydrostatic steering is applied to three different control systems in off-highway machines. ✓ Describe the power flow through a two- speed planetary track steering system. ✓ Describe the power flow through an independent-geared twin track tractor. ✓ Describe the advantages of an electric drive Caterpillar® D7E dozer. A s explained in Chapter 23, Undercarriages, many off-highway machines are equipped with track undercarriage systems. Based on the type of machine, either two- or four-track under- carriages are used on the machine to provide mobility and steering. The vast majority of machines with four tracks use the same steer- ing method (articulation steering) that is used on four-wheel-drive articulated machines. Chapter 25, Wheeled Steering Systems, explains articulated steering systems in greater detail. Machines equipped with two tracks (twin track machines) require steering systems that are unique to off-highway machines. Twin Track Turning Radiuses Tractors equipped with twin tracks require the operator to rotate the track undercarriages at different speeds and/or in opposite directions in order to steer the tractor. The method the operator uses to steer the tractor determines how sharp of a turn the tractor performs. Each of the following track steering methods creates a different turning radius: • Counter rotation. • Brake steer. • Power turn. • Neutral steer. The operator determines the machine’s turning radius by using one of the methods to steer the tractor in a circle. The circle made by the widest point of the machine’s undercarriage forms the turning circumference. The distance straight from the edge of the circumfer- ence to the center of the circumference is the tractor’s turning radius. Not all track-type tractors are capable of performing all of the steering methods.