A bulldozer is a heavy tracked machine used to push large piles of soil, sand, or rubble across a worksite. The wide curved blade in front does the pushing, and many bulldozers also carry an optional rear attachment called a ripper that breaks up hard ground. Crawler-tracked tractors replaced wheeled versions in the early 1900s after wheels kept getting stuck in mud, and Caterpillar's machines from the late 1920s set the modern shape. Modern dozers can weigh over 100 tons. Coloring page of a bulldozer with raised blade and crawler tracks.
