The Caterpillar Sixty Horsepower tractor crawler, was the world's first successful bulldozer. It helped launch the Caterpillar name and legend. Initially developed by the Holt Company of California, with a tricycle-type crawler in that it had rear drive tracks and a forward steering wheel. Holt tractors became successful in West coast logging and farming industries, and formed technology in which William Foster & Co. built the British Army Mark I tanks of the First World War. A Caterpillar D10N bulldozer at work A bulldozer is a very powerful crawler (caterpillar tracked tractor) equipped with a blade. ... Caterpillar Inc. ... The British Army is the land armed forces branch of the British Armed Forces. ... A Mark I tank on 26 September 1916 (moving left to right). ... Ypres, 1917, in the vicinity of the Battle of Passchendaele. ...

From that, the crawler tractor came to stay, and Holt and Best continued to build them into the early, 1920's when the two companies merged in 1925 to form Caterpillar Tractor Company.

The Cat sixty was famous for its overhanging radiator, individually mounted cylinders, lever controls and open clutch. Also, the straight exhaust, rough seat and exposed fuel tank, made the Sixty a work machine. Initially, the crawlers were used to pull farm equipment and road scrapers. They did not have a blade on the front. Later, cable lift blades were rigged up, so that the crawlers could be used as a bull dozer.