Bulldozer

A bulldozer is a large tractor equipped with a metal blade at the front for pushing soil, sand, rubble and other material, most often travelling on continuous tracks that spread its weight and reduce ground pressure. The first bulldozers grew out of a blade attachment for Holt farm tractors; the farmer James Cummings and the draftsman J. Earl McLeod filed a patent for an attachment for tractors on December 18, 1923, issued in 1925, and the term bulldozer broadened during the 1920s and 1930s from naming the blade attachment to naming the whole tracked machine. Bulldozers became a standard tool of construction, road building, mining, quarrying and military engineering, prized for land clearing and grading work that would otherwise require far more labor.