Numptie

As in the pointless motor sport popular in Scandinavia and the low countries.

The trailer the tractors pull seems to have some kind of sliding device which moves from front to back during the 'pull'.

It also appears that the resistance (i.e. the pulled load) increases over length of the 'pull'.

How does that work then ? ... or am I completely misinterpreting what's going on ?

Andrewza

Not sure what you mean, if it slides from the front to the back could be a way of getting a heavy weight over the wheels for good traction without having to accelerate the mass itself much, which means it can go quicker?

Reffro

The trailer the tractors pull does have a sliding weight, that moves forward during the run. The front of the trailer is a sled affair that runs incontact with the ground, so as the run continues the trailer gets harder to pull.

I'll admit its not to everyone's taste, but I often enjoy viewing it when its on telly, its the shear horsepower involved with the big tractors that impresses, plus the variety of engines. Four helicopter jet engines, or two Rolls-Royce Merlin engines running on Methanol, or six Keith Black V8's either way your looking at 6000hp that goes into making a lot of noise and shaking the ground.

Nick VR4

Its called a Sledge
found this http://www.tractorpulling.com/info/sled.html

Tractor pulling is the struggle between the Tractor and the Sled. This is a kind of trailer, with wheels at the tail and a flat plate on the front. The issue is to drag the sled as fare away as possible, across a 100m (300 feet) track. The difficulty is that along the track, the sledge becomes heavier. At he 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 when the total weight of the combination is about 20.000 to 25.000 kilo ! (45,000 to 55.000 lbs.) To reach the finals, they also run a 'pull off'. In this run, the sleds parameters are adjusted to increase drag. This can be reached by several ways:

Let the carriage move faster, by changing the gear setting.
By mounting steel stripes under the sledge-plate.
To make the carriage heavier, by adding 2,5 metric tons (6000 lbs.) of steel weights.
Might a tractor break away from the sled, or the driver gets in trouble, then the sled-operator can put the emergency-cable into action. He pulls a cable, that's connected to the tractor. This cable for example turns of the ignition of the tractor, and make it stop.
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 10m (30 feet) safety-margin between the track (width 30 feet) and the spectators. Sometimes a safetyrail is mounted alongside the track, like highways have.

The most of today's sleds have their own engine. By lowering 2 wheels next to the sled-plate, the sled can roll itself back to the start of the track. They also have some kind of steering, by slightly rotating the sled-plate. Often a team chooses the starting-position of the sled. 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.

Numptie

Perfect ! - cheers fellas !

Link to sledge info

Jay m A

iTrader: (2)

I remember watching these loons on Eurosport One bloke on a spaceframe with 8 chevvy big blocks mounted on it

Also the mud dragsters were a laugh, or the monster trucks that could crush cars but fell over when turning the hairpin halfway round. Barmy but good viewing

Corpulent Tosser

Bet a Scooby would beat one on the twisties though