page_title: Bulldozer
section_title: History
hierarchical_section_title: Bulldozer / History
context_page_description: A bulldozer is a large and heavy tractor equipped with a substantial metal plate used to push large quantities of soil, sand, rubble, or similar material during construction or conversion work and typically equipped at the rear with a claw-like device to loosen densely compacted materials. Most bulldozer tractors are continuous tracked, also termed a crawler.
  Bulldozers can be found on a wide range of sites, mines and quarries, military bases, heavy industry factories, engineering projects, and farms.
  The word "bulldozer" correctly refers to only a tractor fitted with a dozer blade. The word is sometimes used inaccurately for other similar construction vehicles such as a front loader.
context_section_description: The first bulldozers were adapted from Holt farm tractors that were used to plow fields. The versatility of tractors in soft ground for logging and road building contributed to the development of the armored tank in World War I.
  In 1923, farmer James Cummings and draftsman J. Earl McLeod made the first designs for the bulldozer.  A replica is on display at the city park in Morrowville, Kansas, where the two built the first bulldozer. 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."
  By the 1920s, tracked vehicles became common, particularly the Caterpillar 60. Rubber-tired vehicles came into use in the 1940s. To dig canals, raise earthen dams, and do other earth-moving jobs, these tractors were equipped with a large, thick, metal plate in front. (The blade got its curved shape later). In some early models, the driver sat on top in the open without a cabin. The three main types of bulldozer blades are a U-blade for pushing and carrying soil relatively long distances, a straight blade for "knocking down" and spreading piles of soil, and a brush rake for removing brush and roots. These attachments (home-built or built by small equipment manufacturers of attachments for wheeled and crawler tractors and trucks) appeared by 1929.
  Widespread acceptance of the bull-grader does not seem to appear before the mid-1930s. 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.
  Over the years, bulldozers got bigger and more powerful in response to the demand for equipment suited for ever larger earthworks. Firms such as Caterpillar, Komatsu, Case, Euclid, Allis Chalmers, Liebherr, LiuGong, Terex, Fiat-Allis, John Deere, BEML, XGMA, and International Harvester manufactured large, tracked-type earthmoving machines. R.G. LeTourneau and Caterpillar manufactured large, rubber-tired bulldozers.
  Bulldozers grew more sophisticated as time passed. Improvements include drivetrains analogous to (in automobiles) an automatic transmission instead of a manual transmission, such as the early Euclid C-6 and TC-12 or Model C Tournadozer, blade movement controlled by hydraulic cylinders or electric motors instead of early models' cable  winch/brake, and automatic grade control. Hydraulic cylinders enabled the application of down force, more precise manipulation of the blade, and automated controls.
  In the very snowy winter of 1946–47 in the United Kingdom, in at least one case a remote cut-off village running out of food was supplied by a bulldozer towing a big sled carrying necessary supplies.
  A more recent innovation is the outfitting of bulldozers with GPS technology, such as manufactured by Topcon Positioning Systems, Inc., Trimble Inc, or Leica Geosystems, for precise grade control and (potentially) "stakeless" construction. As a response to the many, and often varying claims about these systems, the Kellogg Report published in 2010 a detailed comparison of all the manufacturers' systems, evaluating more than 200 features for dozers alone.
  The best-known maker of bulldozers is Caterpillar. Komatsu, Liebherr, Case, and John Deere are present-day competitors. Although these machines began as modified farm tractors, they became the mainstay for big civil construction projects, and found their way into use by military construction units worldwide. The best-known model, the Caterpillar D9, was also used to clear mines and demolish enemy structures.
caption: A Liebherr bulldozer with a multishank ripper
exif: {}