From Wikipedia-

Tractor pulling, also known as power pulling, is a motorsport competition, popular in America, Europe and Australia, which requires modified tractors to pull a heavy sledge (sled) along a 100 metre track, with the winner being the tractor that pulls the sledge farthest. The sport is known as the worlds most powerful motorsport, due to the multi engined modified tractor pullers.

All tractors, in their respective classes, pull a set weight in the sledge. When a tractor gets to the end of the 100 metre (300 feet) track this is known as a “full pull”. When more than one tractor completes the course, more weight is added to the sledge, and the winner is the one who can pull the sledge the farthest.

The sledge is known as a weight transfer sledge. This means that as it is pulled down the track, the weight is transferred (linked with gears to the sledge’s wheels) from over the rear axles and towards the front of the sledge. 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 further the tractor pulls the sledge, the harder it gets.

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

http://en.wikipedia.org/wiki/Tractor_pull

I will just make this my Tractor pulling thread instead of submitting all the videos.

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