Pulling competitions involve tractors and a weighted sled on a 100m track, which is prepared by grading a level area. Tractors compete in pre determined horse power classes to keep similar size tractors together. The sled used can be adjusted to suit requirements. As the tractor and sled progress along the track a weight box moves forward on the sled gradually increasing the load to make pulling more difficult. As the load increases various tractor set ups and the varying skill levels of drivers will determine the distance of the pull. In most cases the total distance pulled over several runs will determine the winners in each horse power class.