Crawler tractors are designed to pull or push very large loads at slow speeds and can operate on rough terrain, rocky areas, and steep slopes. Crawler tractors move over a pair of steel tracks that revolve around two or three sprockets and a series of rollers. Cleats on the track are 2- to 3-inches tall and provide traction. The cleat and associated portion of the track is called a grouser. Grousers are about 24-inches wide. They are available is a variety of sizes and types appropriate for wet or dry soil conditions, rocky surfaces, and desired ground pressure and weight distribution. Turning is accomplished by reducing the power to one of the tracks. Diesel powered engines vary in size from 65 to 1,150 horsepower. Transmissions can be direct-drive, power-shift, or hydrostatic. Tractor speed varies from less than 1 mph to about 7 mph. Climate controlled cabs are available with power seats and electronically controlled transmission and hydraulic functions. Options are available to control steering and gear selection from one lever and all hydraulic controls from a second lever. Roll-over protection structures are standard with both cab and open canopy models. Bulldozer blades are standard.
Crawler tractors are well suited for many revegetation and reclamation projects because they are rugged and versatile machines that can move tremendous loads relative to their size. Crawlers can be used on rough, debris-littered terrain where rubber-tired tractors cannot. They can also be used on wet, spongy soil. Small crawlers are versatile for confined areas. Crawlers with 65 to 300 horsepower that operate between 2 and 3 mph are used for most rangeland applications. Crawler tractors disturb the soil, especially when turning, leaving it vulnerable to compaction, erosion, and weed invasion.