The steam shovel, invented in 1839 by William Otis, was used to dig the Suez Canal in 1869 and the Panama Canal in 1910. But eighty years after the invention of a digging machine, trenches were still being filled using mule power. In 1923, American farmer James Cummings (1895- 1981) saw mules being used to backfill oil pipeline trenches and realized that a machine could do the job more efficiently. He and draftsman J. Earl McLeod drew up plans, built the first bulldozer from junkyard parts, and won the contract to backfill the pipeline.
The purpose of the bulldozer is to move material from one place to another. Bulldozers have wide tracks to facilitate movement over mud and sand, and a heavy metal plate (or blade) to smooth, push, or carry rocks, sand, soil, or debris. They are the most frequently used earth-moving machines on construction projects today and are essential to quarrying, mining, constructing roads and buildings, and demolition.
Bulldozers were critical to the 1944 Allied invasion of Europe. British armored bulldozers cleared beaches and roads and filled in bomb craters. Some tanks were converted into bulldozers by removing the turrets and adding bulldozer blades. Today, armored bulldozers are the mainstay of combat engineers around the world, who use them for constructing earthworks, removing obstacles, clearing mines, and demolishing structures. Bulldozers are also important tools for responding to natural disasters such as earthquakes. A bulldozer can clear a collapsed high-rise building in a few days. Without bulldozers to clear rubble, a city hit by a major earthquake might never recover.
