Tractor pulling
Truck and tractor pulling, also known as power pulling, is a form of a motorsport competition in which antique or modified tractors pull a heavy drag or sled along an, track, with the winner being the tractor that pulls the drag 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 drag. When a tractor gets to the end of the 100 meter track, this is known as a "full pull". When more than one tractor completes the course, more weight is added to the drag, and those competitors that moved past will compete in a pull-off; the winner is the one who can pull the drag the farthest. The drag is known as a weight transfer drag. This means that, as it is pulled down the track, the weight is transferred from over the rear axles and towards the front of the drag. In front of the rear wheels, instead of front wheels, there is a "pan". This is essentially a metal plate, and as the weight moves toward it, the resistance between the pan and the ground builds. The farther the tractor pulls the drag, the more difficult it gets.
Tractor pulling originated from pre-Industrial Era horse pulling competitions in which farmers would compete with one another to see whose teams of draft horses could pull a heavy load over the longest distance. The first known competitions using motorized tractors were held in 1929 in Missouri and Kentucky. Tractor pulling became popular in rural areas across the Midwestern and Southern United States in the 1950s and 1960s. From there it gradually spread to Canada, Europe, and Australia and New Zealand.
History in the US
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 in teams with 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 urge his horses to pull the load, with more weight added as 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 draft horses, specially bred to have high strength for pulling heavy loads. Today, fixed weights on drags 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.It wasn't until 1929 that motorized vehicles were put to use in the first events at Bowling Green, Missouri, and Vaughansville, Ohio. Although the sport was recognized then, it did not really become popular until the '50s and '60s. It was also realized, at that time, 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 difficult for new entrants.
In 1969, representatives from eight states congregated to create a uniform book of rules to give the sport much-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 modified tractors. Stock tractors were commercially available tractors produced by manufacturers, and modified tractors were the basic tractor chassis with another non-tractor engine mounted on it.
Tractors remained single-engined until two Ohio brothers, Carl and Paul Bosse, introduced the crossbox, which could allow multiple engines to be attached to a single driveshaft. Other innovators during this period included Bruce Hutcherson, with his triple-Rodeck-engine–powered "Makin Bacon Special", Dave and Ralph Banter and their Chevrolet-powered tractors, and the "Mission Impossible" tractors of Tim Engler, which at one point had up to seven supercharged methanol-fueled engines.
Subsequently, modified tractors with four engines were common, while stock tractors tried to catch up by adding multiple large turbochargers, along with intercoolers, 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, turbine engines appeared in 1974, with Gardner Stone's "General" Tractor, a four-turboshaft unit hitting the hook 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 up to and probably would have continued, but in 1989 the NTPA limited displacement to and required natural aspiration, banning supercharging. Today the four-wheel–drive division is one of the most popular with the success of trucks like the Holman Brothers "4-Play" Chevy and Bob Boden's "Studley Studebaker".
Two-wheel-drive (2WD) truck class
The two-wheel–drive division was introduced in 1983.The division imposes a weight limit of on each competing truck, a maximum width of, and a maximum distance of from the centerline of the rear axle to the front of the vehicle.
Alcohol methane engines with up to eight cylinders are permitted, but diesel engines are not. Any wheelbase is permitted.
The National Tractor Pullers Association restricts engines to and two valves per cylinder. They permit tubular steel frames. The maximum tire size for the 2WD class is, with a maximum circumference of when mounted on an rim and inflated to. The ground patch is not to exceed on original tread.
Super stock, pro-stock, and mini-modified
Super Stock tractor Open class uses primarily methanol fuel. The Super Stock Open machines can generate over and of torque, with billet or re-cast engine blocks. Super Stock Open and Super Stock Diesel tractors may use up to four turbochargers in three stages. The Diesel super stock tractors generate close to and of torque and are allowed to compete in the Open class, which very rarely occurs anymore. However, a true Open tractor is not allowed to compete in the Diesel class.There is light Super Stock class which is and the Heavy Super Stock Classes that are.
Diesel 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. The maximum engine displacement is. These engines can achieve around and of torque. In recent years, new classes have been created to appeal to different groups of pullers. There is now a class called Limited Pro Stock that is limited to engine and turbocharger. This class typically pulls at and is slightly restricted, as opposed to the Pro Stock class, which can run up to engine and an unrestricted size turbocharger, along with intercoolers.
The latest addition to Pro Stocks is the Light Pro Stock Class that typically pulls depending on location. These tractors are limited to engines but can run any size turbo. They are not allowed to run intercoolers, however these tractors are making an average of. The light overall weight makes this a driver's class as significant skill is required to keep the tractor on the track.
The mini-modified class is a highly specialized and custom built tractor to be fitted with a naturally aspirated engine, at minimum. NTPA Minis are limited to and uses up to a 14-71 hi helix supercharger. With the driver, they weigh only. Today's engine is capable of a minimum of on methanol or ethanol. Their reputation is known as the wildest ride in pulling, as naturally it is a very high horsepower to weight ratio. Whereas, their larger counterparts, the Modifieds, will weigh, utilizing the same engine that a Mini has, but, with multiple powerplants per custom built tractor chassis. Usually, a maximum of five engines is all that will make the weight limit. Nitromethane and oxidizers were outlawed in 1976.
Antique tractor pulling
Antique tractor pulling is how tractor pulling first got started. As early as 1929, farmers began attaching their tractors to drags, and dragging it down a field to see who could pull it the furthest. People who were event organizers at Bowling Green, Missouri and Vaughansville, Ohio found out farmers were doing this and that it drew spectators. By 1950, county fairs across the country started featuring tractor pulls. Spectators found it fascinating to see machines that would "Pull on Sunday, plow on Monday". At first competitors would use a ‘Human Drag’, meaning a drag that was weighted by humans, different people would be added as the tractor made it down the track. However, organizers began to look at different ways to add weight to the drag, as spectators walking on the drag while moving proved to be a hazard. In the late 60s, a weight-exchanging drag was created, the drag that was created was basically a flatbed truck trailer with wheels near the back and a drag at the front. A mass that is moveable of up to 65,000 pounds or 29,000 kilograms, the mass starts at the back of the sled, slowly working its way up to the top as the drag moves down the track.The tractors are divided into different weight classes based on the tractor weight, the weight classes starting at 2,500 and ending at 14,000 pounds. The tractors could go in any class they choose, with many adding weight for the higher weighted classes. In order to be able to compete in Antique tractor pull competitions a tractor must perform at its original speed. Some pulling competitions will have a ‘dyno’, connecting the PTO shaft on the tractor to a dynamometer to test the horsepower. If a tractor shows it has more horsepower than the original tractor is supposed to have, it is placed into an alternate class called ‘Modified Tractors’.
Most antique tractors when pulling use about in their tires. There is also a drawbar rule, it is to be a minimum of in total steel at any point, as well must be rigid in all directions. The hitching device can be no more than round stock, or less than round stock, the hole has to be diameter. The drawbar on a tractor should be no shorter than from the center of the rear axle to the point of the hitch. All the weights on a tractor must be fixed. All drivers when pulling must remain seated.