A few manufacturers have built prototypes with 3 or more axles but few successful production tractors have adopted this configuration. the best known example is the versatile built Big Roy prototype from the 1970s. A modern version of similar design is being built by DTU, and Valmet built a 3 axle model in the 1970s, and the related AGCO company of Fendt is developing a new 3 axle model.