A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous tracks, though specialized models riding on large off-road tires are also produced. Its most popular accessory is a ripper, a large hook-like device mounted singly or in multiples in the rear to loosen dense materials. Bulldozers are used heavily in large and small scale construction, road building, minings and quarrying, on farms, in heavy industry factories, and in military applications in both peace and wartime. The word "bulldozer" refers only to a motorized unit fitted with a blade designed for pushing. The word is sometimes used inaccurately for other heavy equipment such as a front-end loader designed for carrying rather than pushing material. Description Typically, bulldozers are large and powerful tracked heavy equipment. The tracks give them excellent traction and mobility through very rough terrain. Wide tracks also help distribute the vehicle's weight over a large area (decreasing ground pressure), thus preventing it from sinking in sandy or muddy ground. Extra-wide tracks are known as swamp tracks or low ground pressure (lgp) tracks. Bulldozers have transmission systems designed to take advantage of the track system and provide excellent tractive force. These traits allow bulldozers to excel in road building, construction, mining, forestry, land clearing, infrastructure development, and any other projects requiring highly mobile, powerful, and stable earth-moving equipment. A variant is the all-wheel-drive wheeled bulldozer, which generally has four large rubber-tired wheels, hydraulically operated articulated steering, and a hydraulically actuated blade mounted forward of the articulation joint. The bulldozer's primary tools are the blade and the ripper: Blade Bulldozer blades come in three types: straight ("S blade"), short with no lateral curve or side wings. Can be used for fine grading. universal ("U blade"), tall and very curved, with large side wings to maximize load. combination ("S-U", or semi-U), shorter, with less curvature and smaller side wings. It is typically used for pushing large rocks, as at a quarry. Blades can be fitted straight across the frame, or at an angle. All can be lifted, some, with additional hydraulic cylinders, can be tilted to vary the angle up to one side. Sometimes, a bulldozer is used to push or pull another piece of earth-moving equipment known as a "scraper" to increase