Tractor pulling is a popular motorsport that tests machine power and mechanical engineering to extreme limits. Modified production tractors or multi-engine custom builds compete to pull a heavy sled along a dirt track. As the sled moves forward, internal weights shift to increase resistance, requiring maximum horsepower, traction, and driver skill to cover distance. https://www.aniarticles.com/79770-how-to-inspect-a-second-hand-tractor-before-you-shake-hands