Tractor Pulls in a Fair, Festival or Event
History, It is said that around the 1850s when farming machines were pulled by horse, farmers would boast about the strength of their horses. They would claim that their horse could tow large loads, such as a fully loaded hay cart or wagon. Farmers would challenge one another to contests to prove who had the strongest horse. A barn door was removed and laid fl at on the ground, the horse was then hitched 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 could no longer drag it; the horse pulling the most people the greatest distance was judged 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. Instead of people, fixed weights on sleds are dragged as far as possible.
Courtesy of Wikipedia
Whilst it is said that the term horsepower is derived from this event, in reality the term was coined by James Watt. 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 then, but didn't really become popular until the 50s and 60s, and it was realized that there were no uniform set of rules. The rules varied from state to state, county to county, and competitors never knew what standards to follow. This made the sport diffi cult for new entrants.
In 1969, representatives from eight states congregated to create a uniform book of rules to give the sport the needed structure, 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." Pulling remained basically the same through the 70s, with only stock and modifi ed tractors. Stock tractors were commercially available tractors produced by manufacturers, and modifi ed tractors were the basic tractor chassis with another non-tractor engine mounted on it.
Tractors remained single engine until two Ohio brothers introduced the crossbox which could allow multiple engines to be attached to a single driveshaft. Subsequently, modifi ed tractors with four engines were common, while stock tractors tried to catch up by adding intercooled turbo chargers, but both 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 obsolete. Throughout the 70s and 80s, the modified division continued to thrill crowds by adding more engines, and soon the tractors lost their tractor appearance and turned into high spec dragsters. The limit was reached in 1988 when a tractor with seven engines was built.
As well as piston engines, jet engines appeared in 1974, with a four jet engine unit in 1989. The growing popularity of the sport caused the creation of a new four-wheel drive division in 1976, which captured a large fan base. The engine sizes in these vehicles continued to increase, from 450 cubic inches/7.3 liters up to 700/11.5, and probably would have continued, but the NTPA limited it to 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 created. The super stock, pro-stock, and the mini-modifi ed, which is a garden lawn mower mounted with a supercharged V8. Super Stock Open class uses primarily methanol fuel (some are diesel versions). The Super Stock Open machines can generate over 5,000 horsepower. Super Stock tractors may use more than one turbocharger. Pro Stock Tractors are limited to one turbocharger and diesel fuel is the only allowable source for power, in keeping with the spirit of the original tractors.
In the early days, two main techniques were used. Either a dead weight of fi xed mass was dragged, or the step-on method, where people stood at fi xed positions and stepped aboard as the sled passed. Another rule which has now been dropped was that a speed limit should be observed because of injuries resulting from the increased speed at which they boarded. Today's tractors can achieve theoretical speeds over 125mph. Today's sleds use a complex system of gears to move weights up to 65 000 pounds/29 000 kilograms. Upon starting all the weights are over the sled's rear axles, to give an effective weight of the sled plus zero. As the tractor travels the course the weights are pushed forward of the sled's axles, pushing 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.
All events have their own set of rules, and the following is just an example.
Tractor Pull Rules
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 fl agman 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 disqualifi cation.
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 or 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, or 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.
FARM STOCK CLASS AND OLDER
Weight classes: 3500, 4000, 4500, 5500, 6500, and 7500
1. Must be stock appearing and equipped (PTO, hydraulics, air cleaners, front and rear rims, wheel types, widths and diameter). No stripping of parts. Must have factory covers for removable parts.
2. Stock RPM.
3. Must have an unmodifi ed stock farm drawbar for that tractor. Hitch height as close as possible to 18" without altering.
4. Wheelie bars are not required but strongly recommended. Without wheelie bars a 3.0 speed limit.
5. NO CUT TIRES of any kind.
6. All tractors must have a positive throttle stop.
ANTIQUE/CLASSIC COMBINED 1957 AND OLDER
Weight classes: 4000, 4500, 5000, 5500, 6000,
6500, 7500, 8500, 9500, and 10500
148 | Fair, Festival & Event Promotion Handbook
1. Maximum drawbar height 20": minimum length from center of axle is 18".
2. RPM-10% over stock.
3. No radials, no duals, no chains, and no turbos.
4. No cut tires of any kind.
5. Low gear ONLY.
6. No external engine modifi cation is allowed on the outside of the engine.
7. Examples: external oilers, hemi heads and spacerblocks.
OPEN CLASS 1957 AND OLDER
Weight classes: 4600, 5600, 6600, and 7600
1. Universal joints and drive shafts must be covered at all times.
2. Must have deadman throttles.
3. No radials, no duals, no chains, and no turbos.
4. Must have side shields. Flywheels must be covered with blankets or steel guards. Must be an acceptable cover.
5. Maximum drawbar height 20". Minimum length from center of axle is 18".
6. All tractors exceeding 10% over RPM will be required to have all safety equipment.
7. Maximum speed of 6MPH or less.
8. Cut tires are allowed.