Tractor Pulling



Tractor pulling, also known as power pulling, is a competition using tractors to pull a heavy sled along a 'course' and is very popular in rural areas. Usually the sled gets harder to pull the further you travel. It can make for great spectacle, because although the vehicle makes a lot of noise and smoke and throws a lot of mud everywhere, it doesn't actually travel that far. There are many different classes, from 'factory' tractors to custom built vehicles with multiple powerful engines.

It is said around the 1900's when farming machines were pulled by horse that farmers would boast about how strong their horses were. They would make big claims that their horse could tow large loads, such as a fully loaded hay cart or wagon. To prove this for their neighbors, farmers would challenge one another to contests to prove who had the strongest horse. So a barn door was removed and laid flat on the ground the horse was then hooked up to it and the farmer ushered the horse to drag the barn door along the ground. One by one people jumped on the door until the horse was no longer able to drag it, the horse that pulled the most people the greatest distance was the strongest. This event called draft horse pulling is still carried out today with specially bred horses trained to have high strength and low stamina, but instead of people fixed weights on sleds are dragged as far as possible. Whilst is often said that the term horsepower is derived from this event, in reality the term was coined by James Watt when he invented the steam engine.

It wasn't until 1929 that motorized vehicles were put to use in the first events at Bowling Green, Missouri and Vaughansville, Ohio. The sport was recognized from this time but didn't really takeoff until the 50's and 60's when it was finally realised that there were no uniform set of rules. The rules from state to state, county to county were all different and competitors never knew what standards to follow which made the sport very hard to grasp for any new comers. Finally in 1969 representatives from eight different states got together to create a uniform book of rules to give the sport the structure that was needed and created the National Tractor Pullers Association. The NTPA's early years were events that used standard farm vehicles with the motto "Pull on Sunday, plow on Monday" and it stayed basically the same way through the 70's with only stock and modified tractors. Stock tractors were the commercially available tractors made by well known manufactures and modified tractors were the basic tractor chassis with another non tractor engine mounted on it.

Tractors stayed single engine until a couple of Ohio brothers introduced the crossbox which could allow multiple engines to be attached to a single driveshaft. After this it was usual to see modified tractors with four engines while the stock tractors tried to catch up by adding intercooled turbochargers but both still retained the appearance of a tractor. Soon tractors became single use machines that were not used on the farm making the "Pull on Sunday, plow on Monday" motto a part of history.

Throughout the 70's and 80's the modified division continued to thrill the crowds adding more and more engines and very soon the tractors lost their tractor look and turned into high spec dragsters. The limit was finally reached in 1988 when a tractor with seven engines was produced. As well as piston engines jet engines made an appearance in 1974 with a four jet engined one appearing in 1989. The growing popularity of this sport created a new division in 1976 called four wheel drive which immediately caught a great fan base. The engines in these vehicles kept on growing and growing from 450 cubic inches/7.3 litres up to 700/11.5 and probably would have carried on but the NTPA capped it at 650/10.6 naturally aspirated and no blown engine in 1989. Blown engines were allowed but only in the new 1986 division of two wheel drives or "funny cars" as the NTPA called them.

Three other divisions were made: the super stock, pro-stock and the mini-modified division which is a garden lawn mower mounted with a supercharged V8. Super Stock Open class uses primarily methanol fuel (there are some diesel versions). The Super Stock Open machines can generate over 5,000 horsepower. Super Stock tractors may use more than one turbo. Pro Stock Tractors are limited to one turbocharger and diesel fuel is the only allowable source for power - keeping in the 'spirit' of the original tractors.

There are many different organizations with many different rules within tractor pulling. A small list includes:

1. ATPA - The American Tractor Pullers Association
2. NTPA - The National Tractor Pullers Association
3. ATPA - Australian Tractor Pullers Association Inc.

In the early days two main techniques were used either a dead weight of fixed mass was dragged along or the step on method where people stood at fixed positions and stepped on as the sled came past. Another rule which has now been dropped was that a speed limit should be observed because they found the people who where stepping on were getting their ankles and legs twisted or broken from the increased speed at which they had to step on. Today's tractors can achieve theoretical speeds of more than 125mph.

Today's sleds use a more complex system of gears to move weights of up to 65 000 pounds/29 000 kilograms. The way in which it does this is to start off with all the weights over the sleds rear axles to give it and effective weight of the sled and plus zero. As the tractor makes its way up the course the weights are pushed forward of the sleds axles pulling the front of the sled into the ground synthetically creating a gain in weight until the tractor is no longer able to overcome the force of friction.

Rules:

Here are some of the basic rules for tractor/power pulling.

1. Tractor must be operated in a safe manner at all times.
2. Driver must be seated in a safe manner when pulling or will be disqualified.
3. Driver must observe the flagman and clutch immediately on the red flag or will be disqualified.
4. When hooking and unhooking from the weight transfer, tractor must be in neutral and the driver’s hands must be free of the tractor.
5. Drawbar must have a 3” opening of ¼ turn clevis with a 3” opening. Hook must swing freely. No free floating hitches.
6. Tractors will weigh before pulling when a portable scale is present.
7. All weights must be in solid form and securely fastened to the tractor on brackets, not on three point hitches.
8. Any parts falling off the tractor after being hooked and until the tractor is unhooked will result in disqualification.
9. Next puller must be on deck and ready to pull.
10. Full pulls and ties will repull.
11. No front weights farther than 24” from the farthest front casting of the tractor (includes weights). For two-cylinder standards, 24’ from the front grill.
12. Stock model block numbers or replacement blocks, ONLY.
13. No homemade manifolds.
14. Original type of carburetor that came with the tractor.
15. All original major parts must be intact: hoods, radiators, fenders, front ends, etc.
16. 1957 and older by serial number. If series started prior to ’57 but ran ’58-’59, it will be allowed, but cannot start in ’58. Exception-Farm Stock current and older.
17. Gas, diesel, of LP fuels only. No alcohol or nitrous oxide fuels may be used in tractors. Tractors manufactured to use diesel fuel cannot be converted to gas or LP. Tractors will be naturally aspirated-no fuel injection or gas under pressure is allowed unless factory equipped. (Example: LP tractors). Electric fuel pumps are allowed with a needle and seat in carburetor.
18. Trophies for 1st, 2nd, and 3rd places.Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts.
Virtual Magic is a human knowledge database blog. Text Based On Information From Wikipedia, Under The GNU Free Documentation License. Copyright (c) 2007 Virtual Magic. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

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