Dan Stork left remembers tractor pulls at county fairs where the spectators became participants in ways that could have given new meaning to the term 'dead weight. They [the tractors] were basically out of the field. In the late 60s, a weight-exchanging sled was invented. Basically, the sled is like a flatbed truck trailer with wheels at the back and a sled at the front.
A moveable mass of up to 65, pounds 29, kilograms starts at the back of the sled over the wheels. The sled starts out a pull with an effective weight of the sled plus zero. As the tractor begins its pull, the weight is moved forward at a set rate, pushing the front of the sled farther and farther into the ground, increasing the friction that the tractor is pulling against. The inventor of one of the earliest sleds named the contraption the "Heartbreaker.
Gradually, competitors began modifying their weekday tractors and some built machines for the competitions only. In the 60s, two Ohio brothers figured out a way to add a crossbox gear system to allow several engines to connect to a common driveshaft.
Pretty soon, tractors with four engines were common and at least one machine got up to seven engines. Turbo-chargers were added to engines. The organizers had to split their divisions into "stock," "modified" and even "super-modified. It wasn't long before competitors were adapting jet engines from helicopters to their tractor frames.
WPI is a stockholder's company that not only handles the business affairs of the NTPA, but also includes a marketing department and a publications division. A staff of 15 dedicated professionals work in the Columbus, Ohio headquarters or from a satellite office. The other ingredient in making an event successful includes hundreds of workers and trained volunteers essential in producing an NTPA sanctioned event. Even though both boards have unique aspects to their function to the business of professional truck and tractor pulling, they work together.
Lives have been saved over the years, thanks to the tireless efforts of many persons who have served on the NTPA and WPI boards, bettering the sport as a whole. Today, other pulling organizations and promoters are adapting to this standard. Such is the life of a leader. Light Unlimited GN - 6, pounds, no turbines. Unlimited GN - 8, pounds, any power plant making weight. Box - Contains the weight used to stop the vehicle and moves up the length of the sled rails progressively during the pull, driven off the front set of sled wheels.
Pan - Applies the force of the weight to the ground creating needed friction. The sled starts with only the front of the pan touching the ground.
Bars attached to the bottom of the pan help make added friction at the end of the pull to stop pulling vehicle. Trip - Sits between the frame rails of the sled.
As the box moves up the rails the trip is hit and starts the push-down system. The trip is adjustable. Kill Switch and Hook - The kill switch is always hooked first, allowing the sled operator to stop the engine of the attached vehicle in the event of an emergency or if the vehicle breaks free of the sled.
Sled Operator - The driver of the sled. Has the responsibility of maintaining a controlled pull at all times. May pull kill switch if they feel something is out of control. State Leve l - The grass roots of organized pulling, the first stepping stone to the other levels. Competition vehicles may be as powerful as higher levels. Some classes are not available at this level, while some are only available at this level. Super National - Highest level of competion and reserved for the very best events.
Grand National competitors also follow this level of competition. Binder : International Tractor. Bite : Traction. Blower : Supercharger. Boost : Air pressure generally by turbos or superchargers. Box : Part of a weight transfer machine that carries and transfers the weight. Brush Pull : Non-sanctioned pull. Cam : The camshaft, a revolving engine part that moves the valves up and down. Carb : The carburetor. Clay : The most desirable track surface. Cleats : The tread on a tractor tire.
Cubes : Cubic inch displacement of an engine. Cut Tires : Trim the tire bar to a preferred angle for maximum bite. Deere : A John Deere tractor. Drawbar Height : The distance between the drawbar and the track surface. Drop the Hammer : Hitting the throttle hard. FWD: Four wheel drive truck. Fuel : Either Alcohol or Diesel fuel. Full Pull : Pulling the entire length of the track.
GN : Grand National level of pulling. Gooney : A puller's helper. Grenade - Damage to engine, usually terminal. Headers : Exhaust pipes designed for free exhaust flow.
Hemi : A Chrysler engine with a dome-shaped combustion chamber. Hired Gun : A driver who drives tractors or trucks other than his or her own. Hook : The point of attachment to tractor's or truck's drawbar. Hooking Up : Tires getting a bite on the track. IH : An International Harvester tractor. Also International Kill Switch : A required hook-up that automatically kills the engine if the tractor becomes unhooked from the sled.
Mini : Small modified tractor, lb. MM : Minneapolis Moline tractor. Modified: Tractor using any combination of engines, transmission and final drive.
Mopar: Chrysler products. Tractor pull sleds are specifically engineered for the sport and are the only thing that keeps each tractor from making a full pull down the foot pitch. This simultaneously simple and perplexing piece of machinery can be quickly understood with the help of a tractor pull professional. Here is how a sled works, as told by the volunteers at the Banks BBQ tractor pull.
As the tractor pulls the sled, the sprocket A in the above diagram spins, pulling the weight box B forward on a track that runs the length of the sled. As the weight box moves forward, it increases resistance exponentially by weighing down the pan C and pushing it ever deeper into the dirt. The farther the tractor pulls the sled, the more difficult it becomes to do so. The weight box can impose up to 36, pounds of additional drag on a tractor, which is more than most can handle before completing a full pull.
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