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Belted Tractor

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Agricultural Equipment
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2001 John Deere 9400T Belted Tractor
The belted tractor, which travels on rubber crawler tracks, was designed specifically for agricultural tasks. While crawler tracks were invented more than a century ago, metal crawlers were not ideal for farms. They were too slow and unable to travel on certain surfaces without severely damaging them. Instead, farmers relied upon wheeled tractors for most of their farm work.

Rubber crawler tracks were invented in the 1920s, but the first use on a commercially available tractor was the Oliver/Cletrac HNC, which was discontinued due to problems with the tracks. A successful tractor was the 1987 Caterpillar Challenger Model 65. It improved traction without harshly reducing speed capabilities and was capable of driving on concrete without damaging it.

So, belted tractors, in comparison to crawler tractors, emit less noise and less hazardous vibration levels for the operator, they can be used on asphalt surfaces without damage to the road surface, and are capable of operating at higher speeds.[1]

Contents

[edit] History

[edit] Rubber Half-tracks

Frenchman Adolphe Kegresse developed the first rubber crawler tracks in the 1910s. They provided lightness of weight and considerable flexibility unavailable with standard metal crawler tracks. These new tracks were equipped with rubber teeth, which engaged the inner pulleys.

In the early 1900s, Kegresse worked for the Russian Royal Family as a technical manager of the imperial garages. He was often subject to Tsar Nicholas II’s demands. During a winter hunting excursion the Tsar requested to follow the hunt in one of his cars. Kegeresse attempted to explain the vehicle could not safely travel through the snow without becoming stuck. He even staged a photo of a snow-trapped car to display his point. But the Tsar remained determined to hunt in comfort.

2004 Bell 4206DT Belted Tractor
So Kegresse began experimenting with a system of continuous rubber tracks, which could be attached to a car to help traverse moister terrain. Metal crawlers were already on the market, but snow had proven to often damage its tracks. Rubber, conversely, did not collect the snow and was therefore perfect for winter travel. The rubber crawler tracks were affixed to the rear axle, replacing the rear wheels, while the front tires remained intact to aid in steering. These machines were called "half-tracks", because only half of the vehicle had tracks. Initial tests were successful.

After the Russian Revolution of 1917, Kegresse returned home to France. He left many of his experimental vehicles behind, which were stolen by the Bolsheviks and used in military actions against the Polish. However, Polish forces captured one of the vehicles, sending it to Paris to be studied by the French army.

Two French Industrialists, Andre Citroen and M. Hinstin, took interest in Kegresse’s design and developed their own model in 1921, the Autochenille. It combined a Citroen model car with the Kegresse tracks. These models experienced much of their own successes. Eventually, Adolphe Kegresse was hired by Citroen to aid in further developments. They even equipped models of the Autochenille with skis. The vehicle’s success on snow made Citroen believe it could be just as successful on other terrains.

Citroen developed a test that would work as a unique promotional campaign. He planned to prove the new vehicle’s versatility by sending it across the Sahara desert. Five belted machines, constructed with aluminum to minimize weight, equipped with extra radiators were sent across the desert in December 1922. They were powered by 88.5- cubic inch (1452-cc) engines with a bore and stroke of 2.68 x 3.94 inches (68 x 100 mm) driving through a three-speed transmission.[2] The rear axle was a two-speed unit, which increased the range of the transmission enabling the machine to traverse a wider variety of terrains. The Autochenilles’ traveled at a maximum speed of 28 miles (45 km) per hour over the 2,250-mile (3,621 km) trip. The 20-day venture was a success.[3]

By the early 1930s, Kegresse-model half-track machines were being developed throughout Europe and eventually deported from France to the U.S. for testing. This resulted in rubber track models being developed by a number of U.S. manufacturers.

[edit] Converting for Agriculture

However, it was another 50+ years before these advancements were developed into full-length tracks and adopted by the agricultural industry. In 1987, Caterpillar released the Challenger Model 65, the first successful belted tractor.

Four-wheel drive tractors were hugely popular in the 1970s, but declined in the 1980s, opening up the market for a new machine. Caterpillar quickly began developing a rubber-tracked tractor. The company adapted proven technology from its line of XT hydraulic hoses and placed rubber tracks on its Cat D6 crawler tractor. After successful tests they developed an original machine modeled after modern agricultural tractors. Other manufacturers eventually began to develop their own models.

Case IH developed a model called the Steiger Quadtrac tractor in 1996. In place of wheels, Case substituted four individual rubber crawler tracks. Case IH claims this design provides a “larger footprint for greater flotation, and that lets you get into fields earlier, and drive through wet spots, where you couldn’t with traditional tires or even two tracks.”[4] Case is currently the only manufacturer to use the four individual tracks design, while others model their belted tractors after traditional two-track crawler tractors.

[edit] Features/How it Works

As a type of tractor, it is designed for pulling and powering various types of agricultural attachments and equipment. Its standard features include operator cab, diesel engine, rubber tracks, hydraulic outlets and a drawbar. The rubber tracks operate in the same process of traditional crawler tracks.

[edit] Wheels vs. Tracks[5]

A series of tests were done by the Agricultural Technology Center in Alberta, Canada, to discover the advantages, if any, of using a rubber tracked tractor versus a wheeled model. Various Caterpillar Challenger belted tractors were tested against a number of four-wheel drive models with single, dual, and triple tires. They were tested to measure engine power, drawbar power, speed, slip, and ride quality. The tests were conducted in various soil conditions throughout Alberta and Montana during 1991 and 1992.[6]

The tests display significant differences between tracks and tires, but the Agricultural Technology Center was unable to conclude if one was better than the other.

“On the plus side for the tracks were pull and the ease of optimizing the traction system performance. The tracks also showed a slight plus in power delivery efficiency. On the plus side for tires were steering control and overall cost. A neutral issue for both systems was ride quality. The issue of soil compaction was not resolved by the tests.”[7]

“Rubber belt tracks are an option in farm machinery selection. So are four-wheel drive tractors with single, dual, or triple tires. Each system has strengths and weaknesses and provides certain features and performance characteristics. Potential owner/operators need to balance these pluses and minuses against their operating needs to decide what will work best for them.”[8]

[edit] Common Manufacturers

[edit] Additional Photos

2000 Caterpillar Challenger CH55 Belted Tractor
2000 Case 9370 Quad-Track Belted Tractor

[edit] References

  1. Yu, Tingmin. The Tractive Performance of a Friction-Based Prototype Track. PDF> 2008-09-23.
  2. The Ultimate California Car Accident Handbook. AutoLemon. 2008-09-23.
  3. Crossing the Sahara. Citroen. 2008-09-23.
  4. Products. Case IH. 2008-09-23.
  5. Department Docs. Agric. 2008-09-23.
  6. Dept. Docs. Agric. 2008-09-23.
  7. Dept. Docs. Agric. 2008-09-23.
  8. Dept. Docs. Agric. 2008-09-23.

[edit] External Links