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.
Facts
Patent or First-Use Date SignificanceThe front blade that gave the bulldozer its name began as an attachment sold for existing farm tractors, but hydraulic-powered blades were common enough on construction sites by the 1940s that the word bulldozer had come to mean the whole machine rather than just the attachment. 1 Sources
1. Bulldozer (Wikipedia)
Wikipedia contributors, Wikimedia FoundationHistory section, Cummings and McLeod paragraph
On December 18, 1923, Cummings and McLeod filed U.S. patent #1,522,378 that was later issued on January 6, 1925, for an "Attachment for Tractors."
History section, hydraulic blade sentence
The addition of power down-force provided by hydraulic cylinders instead of just the weight of the blade made them the preferred excavation machine for large and small contractors alike by the 1940s, by which time the term "bulldozer" referred to the entire machine and not just the attachment.
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