Tractor pulling

Truck and Tractor pulling, also known as power pulling, is a motorsport competition, popular in United States, Europe (especially in the Netherlands, Denmark and Germany), Australia and Brazil, and New Zealand which requires modified tractors to pull a heavy sled along a 35 foot wide, 330 foot long track, with the winner being the tractor that pulls the sled the farthest. The sport is known as the world's most powerful motorsport, due to the multi-engined modified tractor pullers.

All tractors in their respective classes pull a set weight in the sled. When a tractor gets to the end of the 100 metre track, this is known as a "full pull". When more than one tractor completes the course, more weight is added to the sled, and those competitors that moved past 300 feet will compete in a pull-off; the winner is the one who can pull the sled the farthest.

The sled is known as a weight transfer sled. This means that as it is pulled down the track, the weight is transferred (linked with gears to the sled’s wheels) from over the rear axles and towards the front of the sled. In front of the rear wheels, there is a "pan". This is essentially a metal plate and as the weight moves over this the resistance builds. The farther the tractor pulls the sled, the more difficult it gets.

The most powerful tractors, such as those in the 4.5 modified class in Europe, can produce over 10,000 horsepower.

Prior to the invention of the tractor, when farm implements were pulled by horses, farmers would boast about the strength of their teams and seek to compare and contest against one another to see who had the most powerful animals. In some cases they compared horse teams pulling large loads over distance, such as a fully loaded hay cart or wagon. In other situations, a flat board or skid would have a horse or team of horses then hitched to it; weight would be added, usually in the form of rocks, and the driver would ask the horses to pull the load, with more weight added and competitors were eliminated; the animals pulling the most weight or for the greatest distance were judged the strongest. These events became the formalized sport of horse pulling, which is still carried out today with specially bred draft horses bred to have high strength for pulling heavy loads. Today, fixed weights on sleds are dragged for a set distance and additional weight is added in successive rounds. While it is said that the term horsepower is derived from this event, the concept was developed earlier, in experiments and measurements performed by James Watt and Mason Worrell.

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