Caterpillar is the world's largest manufacturer of construction and mining equipment, diesel and natural gas engines and industrial gas turbines. The name Caterpillar has been attributed to attempts to solve the problem of heavy steam tractors becoming bogged down by replacing the wheels on a machine with a set of wooden tracks bolted to chains in 1904, prompting the observation by a company employee that the machine crawled "like a caterpillar". The company moved to East Peoria in Illinois a few years later, eventually buying a factory to begin operations. The name Caterpillar was trademarked in 1910.