If you have ever been to a tractor pull or seen one on TV, then you know that today's competition tractors don't have much resemblance to a normal farm tractor. In fact, the biggest tractors at these events use super-charged funny car engines or even gas turbine engines with thousands of available horsepower - they could probably pull the Empire State building down the street if they had to!
But have you ever thought about where these gigantic mutant tractors come from? They come from people who happen to have an interest in big engines and big tires - they get to work in their garages and they build the things by hand! The available budget and the spare parts that are laying around control the size of the tractor and the amount of power it has.
In this edition of the Inside Series we go inside a typical mid-tier competition truck called Little Red so that you can see what goes into one of these tractors:
Little Red is a championship truck that comes out of a small garage in Zebulon, North Carolina called AA Auto and Towing. It is hand-built by the proprietor and makes frequent appearances at a variety of competitions. The great thing about a vehicle like this is the creativity and ingenuity that goes into its construction.
Like all competition vehicles, Little Red bears only the slightest resemblance to a normal vehicle. You get a good idea of some of the weirdness when you "open it up", like this:
How many trucks do you see on the road today that can do this? About the only thing stock about it is the sheet metal in the cab. You can see that the cab started life as a compact Chevy pickup. The doors and hood have been stripped and welded to the cab, and the cab had been reinforced with sheet metal and mated to a fabricated truck bed (which has no floor). The entire body is a single unit hinged at the rear and operated by an electrical hydraulic system (an electric motor drives a hydraulic pump which operates a hydraulic cylinder mounted at the back) for easy access.
The Cockpit, Brakes and Motor
You get a sense of just how odd and customized one of these vehicles is by looking at the cockpit:
This vehicle has 2 brake pedals - one for each foot. The lever to the right of the seat is the throttle, which is hand-operated. The reason for this arrangement is obvious to anyone who has been to a tractor pull - as soon as the vehicle starts pulling, the front wheels come off the ground. That makes the steering wheel useless. The driver steers by applying the brakes individually on the left or right rear wheels, and since the steering wheel is not used it makes sense to operate the throttle with a free hand!
The engine is a naturally aspirated V-8 in the 6 liter range. "Naturally aspirated" means that there is no turbo-charger or supercharging used. Two huge Holley carbs and their air filters sit on top of the engine. This engine burns a combination of gasoline and alcohol that is mixed in the engine (there are separate tanks for the two fuels in back).
Oil Pump and Truss Frame
In the following close-up you can see an oil pump on the lower left and a fuel pump on the lower right. Both are driven directly by the crank shaft. A small motor is attached to the left side of top belt, and it is driving the water pump. The large black hoses heading toward the back carry water for the radiator to and from the engine's water pump.
In the "bed" of the truck you can see the vehicle's substantial truss frame:
Bolted to the frame from front to rear are the alcohol tank (large silver cube), the radiator and fan, the electric hydraulic pump and cylinder to raise and lower the body, a gas tank (smaller red cube) and 2 batteries. Also visible is one of the large rear tires (about 4 feet in diameter). The large disk next to the tire is a huge custom brake rotor, also visible in this shot:
One of the most interesting and unexpected components on this truck, and also one of the best examples of ingenuity and "using the parts on hand", is the rear differential. When you look at the hubs on the rear wheels you find the "Franklin Logger" imprint:
The rear end is actually the planetary differential from a log skidder!
What you get from examining a vehicle like this is a sense of the knowledge and skill of the creator. Think how much the person has to know about all of the different components, and then the skill required to bolt and weld them together into a working vehicle. It is truly an accomplishment!
One of the most amazing things about modern society is the sub-societies hidden within it. Tractor pulling is a good example of this phenomena - every permutation you can imagine from customized lawn tractors to Bigfoot make up the spectrum, and there are thousands of fans in each niche. If you are interested in learning more about tractor pulling, the following links will get you started: