A used Caterpillar excavator or wheeled digger makes a superb second-hand purchase with many machines available on our listings as well as Caterpillar crawler tractors, the forerunner of the Challenger brand of today. Caterpillar was formed by the merger of Holt and Best in 1925 and soon became the most successful producer of crawler tractors in North America followed by a huge range of construction machinery, including back hoes from 1985. Diesel engine production was also at the heart of the business with many power plants being used to power other companies’ equipment as well as its own. Towards the end of the 1980s Caterpillar developed a rubber-tracked agricultural crawler range, dubbed Challenger, which began a revolution in farm power and was produced up until AGCO bought the Challenger line from the firm, allowing Caterpillar to concentrate on construction machinery.