Last Saturday, grandson Samuel was on the phone asking a rhetorical question whether I knew when the "tractor pulling" event was taking part near Oulu. He had actually found out, using Google, and said it was on Sunday at a small village near Oulu.
Samuel and I had been to a tractor pulling event about 3 years ago, and both of us had greatly enjoyed it. He had eaten his favourite fried fish off the top of my head as he sat on my shoulders to watch the event.
So off we went on Sunday. It was raining so we bought ourselves caps.
What is tractor pulling? How did it start? What is the status of tractor pulling these days?
For all these answers and more detailed informations,visit the official European tractor pulling (EPTC) website. Here are some salient points from this excellent site.
At the beginning of the last century, when the farming sector was growing in the US, farmers used to boast about what size boulders their horses could pull out of the ground. This led to a competition and "boulder pulling" as sport was born.
When tractors were introduced, the sport became called as tractor pulling. The sport has become very very popular.
As tractors became larger, the competition became more fierce. Boulders became too large to handle. So a dead-weight sledge was created. It was a vehicle with weights on it which was connected to the tractor with a chain. Either the tractor took off with the sledge or it lost its grip and dug into the tracks. To get more grip the tractors were loaded with anything that was heavy.
Subsequently the idea was born to make sledge heavier as it was pulled. Volunteers stood next to the track and stepped on the sledge as it went by. This was called as the "step-on-sledge". The tractors were rated depending on the distance that was covered. If the tractor reached the end of the track this was called as the "Full Pull". All those that reached that were involved in the "Pull-Off".
Finding volunteers to step on the sledge became difficult as the tractors got faster and faster and safety was an issue.
The weight transfer machine was developed. This sledge has wheels at the rear end. At the start of the pull the weights are above the wheels. As the tractor starts to pull, the weights are moved forward to the sledge plate by a chain. The friction increases. At some point the tractor looses grip.
This principle is being used today.
From a technical point of view there have been many changes. The almost standard tractors from 1997 made place for the multiple-engine creations that can now easily compete with the tractors from the United States, where it all began...
Tractor pulling is the struggle between the Tractor and the Sledge. This is a kind of trailer, with wheels at the tail and a flat plate on the front. The issue is to drag the sledge as far as possible, along a 100 metre track. The difficulty is that along the track, the sledge becomes heavier. At the beginning of the pull, a carriage loaded with steel plates is above the wheels. Along the track, this carriage moves to the front and generates a larger pressure on the plate on the front. This causes an ever increasing drag. The tractor will eventually not be able to go any further. The goal is to use a combination of force, speed and balance that the 100m line is passed. This goal is called a 'full pull'. Full pulls in less then 10 seconds are possible. And this even when the total weight of the combination is 20,000 to 25,000 kgs!
To reach the finals, they also run a 'pull off'. In this run, the sledges parameters are adjusted to increase drag. This can be done in several ways:
• Let the carriage move faster, by changing the gear setting.
• By mounting steel strips under the sledge-plate.
• To make the carriage heavier, by adding 2500 kgs of steel weights.
If a tractor breaks away from the sledge, or the driver gets in trouble, then the sledge operator can put the emergency-cable into action. He pulls a cable that is connected to the tractor. This cable will turn of the ignition of the tractor. If this doesn't help, then there is a pile of dirt at the end of the track to stop the tractor.
Also there is a 10 metres safety-margin between the track and the spectators. Sometimes a safety rail is mounted alongside the track, as where Samuel is sitting in this photograph.
Sledges have their own engine. By lowering 2 wheels next to the sledge-plate, the sledge can roll itself back to the start of the track. They also have some kind of steering, by slightly rotating the sledge-plate. Often a team chooses the starting-position of the sledge. By locating it on the right side of the track, they create more margin at the left site. This is done if the team assumes the tractor will deviate to the left during the pull.
The best pull is made when the tractor has a quick start. At the start of the track the sledge is easy to pull, so a lot of speed can be developed. When the friction increases, the speed of the sledge and tractor makes that the whole keeps sliding a few meters more. Nowadays, when the tractor driver kills the engine at about 90 or sometimes 80 meters, the speed is that so high that a full pull is easy.
The covered distance is measured with infra red equipment which has an accuracy of about 1 cm.
With each pulling event, it is not only the power that makes a tractor win. The most important is the balance of the tractor. A 4000 hp tractor can sometimes beat a 7000 hp.
Power explosions are accompanied with a great amount of noise (over 110 dB).
In 1977, the sport of Tractor Pulling from the United States came to Europe. Truck and Tractor pulling has the same grand manner and high grade as the Formula-1 autosport. F1 drivers have 'only' 700 horsepower, while the trucks and tractors in truck and tractor pulling have many times that.
The development of the sport has been rapid during the last 25 years. It is now in twelve European countries: Austria, Belgium, Denmark, Finland, France, Germany, Great Britain, Luxembourg, Norway, Sweden, Switzerland and The Netherlands. Italy, Portugal and Spain may be added in a short time.
and European Champion D-Sigma Power
The tractors and their classes.
Modified
These are self designed tractors. They compete in the 2500, 3500, 4500 or 5400 kg weight classes. All types of parts are allowed. The weight and size have to be within the rules. Also the number and types of engines are limited. There also strict safety-rules, to prevent the tractor, driver and the spectators from any harm.
The self-built chassis are usually fitted with a rear-axle from a truck or shovel. The inside is replaced with stronger gears. The tires size is limited to 77.5 to 81.25 cm. The original tractor tyres profile is always decreased to less then a centimeter, to be able to generate a lot of wheel-spin. Otherwise the tractor digs itself in, but gain a lot of grip, the tire-pressure is very low. Most tractors fly over the track. And flying is what most of the engines used to do. A lot of the V12 engines have been built in 1932 and have been used as a plane-engine during WW II by the American or British Air force. Very popular today are gas-turbines. These originate from transport helicopters and are free-power turbines only. Since the USSR broke up, a very popular engine is the Russian Isotov turbine. With it's 2000 hp each, a 8000 hp tractor is not a great problem. In the US the V8 racing-engines are very popular. In Europe the tractors are fitted with up to 9 engines, depending on the type and weight class (5/6 with blower).
The force that's produced by these tractors is not only visible. You can feel these during their pull.
Super Standard / Super Stock
These have heavily tuned standard agricultural tractors, that weigh 3500 or 4500 kg. The base of the tractor is a normal tractor. But not much of that machine is left. Everything that's normally needed for field operation is removed. The block, the clutch housing, the gearbox housing and the rear-axle have to be original. The inside of those parts can be modified. To increase the engine's power, a maximum of 4 turbo's can be fitted, as long as it all fits under the original hood. With the great amount of air that flows into the intake, a lot of diesel can be injected into the cylinder. When the air is compressed by the turbo's, a lot of heat is produced. To prevent the turbo's from melting, a spray of water is injected into their intake. This water leaves the exhaust as water vapor. By this means, it's possible to multiply the original power by 10. 2000 hp is possible. To make sure this power reaches the wide rear-tires, the parts of the transmission are replaced by stronger ones. Also unnecessary gears are removed.
A different kind of engine tuning is found on an "alky-burner". These tractors use methanol (a type of alcohol) instead of the usual diesel. The usual cylinder-head is replaced by one that has sparkplugs. The advantage of methanol is, that it's able to burn a longer time than diesel. Therefore there is more power generated and the engine suffers less stress. There are a lot of modifications needed and setting of the fuel-system. and the turbos need a lot of experience. But the results are there. Some 2500 hp are no exception.
A 'simple' and limited version of this class is the Pro-stock. From 1995 this class also competes. The basic tractor can be fitted with only one turbo-charger. Also their tires are a bit thinner. Although 62 centimeters isn't what you call small. The maximal weight is 3500 kilo.
Minipuller
These are small 950 kilo modifieds. That weight includes driver and fuel. This class uses it's own special, small sledge. These tractors are self designed and built. They use V8 engines and helicopter turbines. The power can be up to 3000 hp. The average is about 1700 hp. Due to the enormous power and the low weight, these machines are very difficult to control. It shows when they pull. To reduce the difficulty of steering the rear axles are mostly self-developed. The gearbox is not more than a 1 speed. A mini may have Rover Meteor V12 plane engine, that weighs about 680 kg. itself, or an Isotov TV3 turbine from a Russian heavy transport helicopter. These engines are far to heavy. With a ultra light chassis (just 18 kg) and a stripped engine, it is possible. Sometimes the owner's son drives this tractor to make sure that driver's weight is very low. The age of 16 to 25 years is no exception.
The sport of Tractor Pulling can rightly be called "The world's most powerful motorsport"!
