Equipment Specs
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Crawler Tracks

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Mechanical Features and Designs
A set of crawler tracks
Crawler tracks, sometimes called caterpillar tracks, aid in the transportation of a vehicle. They serve the same purpose as wheels, except they distribute weight more evenly over a larger surface area, decreasing ground pressure and thereby keeping them from sinking in moist terrain. They are also more resistant to shrapnel, such as nails or broken glass, and sharp fluctuations in the ground.

The tracks are constructed from modular chain links, which, when put together, compose a closed chain. These links are broad and made of durable metal. Between every two pieces of chain, there is a joint that enables them to change the angle between themselves. This allows the track to be flexible and maintain an elliptical shape.[1]

There are two main types of suspension systems for crawler tracks: Christie Suspension and Vickers Suspension.


[edit] History

[edit] Origins

While elementary crawler track design has existed for thousands of years, the introduction of modern types is attributed to an English writer and inventor named Richard Lovell Edgeworth. He established his design in 1770.

Another Englishman, named George Cayley, patented his own track design in 1826. It was called the “universal railway” and it appeared in an engineering publication called The Mechanics Magazine.[2]

Eleven years later, Russian inventor Dmitry Zagryazhsky designed his “carriage with mobile tracks.”[3] He quickly patented his invention, but due to lack of funds, he was unable to build a prototype, and his patent expired two years later.

In 1848, a British engineer named James Boydell patented his “endless railway wheel.”[4]

Crawler tracks were used on many vehicles by the Western Alliance during the Crimean War of 1853 to 1856. However, none of these were mass-produced.

In fact, the first commercial success for crawler tracks was by American Alvin Lombard. He assembled and patented the first steam log hauler track system in 1901. By 1917 he had produced 83 Lombard Log Haulers. Meanwhile, Lombard was selling licenses to other manufacturers to sell similar machines. Benjamin Holt purchased a license in 1903.[5]

Holt had established his own company, Holt Manufacturing Co., which would eventually become Caterpillar. He began designing his own crawler tracks based on Lombard’s.

Meanwhile a British company called Richard Hornsby & Sons was also designing. Chief engineer David Roberts patented his own design in 1904. His crawler tracks were steered by alternating the speed of the left or right track, whereas the Lombard system was equipped with a pivoting wheel for steering.

Eventually Holt’s company bought Hornsby & Sons' patent and basically controlled the crawler track market and their development.

[edit] Caterpillar Tracks

The tracks are often called “caterpillar tracks” because they resemble a caterpillar moving along the ground.

However, the originator of the name is up for debate. Americans typically attribute the moniker to Charles Clement, an American photographer who was hired by Benjamin Holt to take archive photos of his crawler tractor. The British attribute the name to a British soldier who saw a Hornsby & Sons presentation of its steam crawler tractor.

Either way, Holt’s new company eventually adopted the name: Caterpillar.

[edit] References

  1. History of Tracks. Darlind. 2008-09-29.
  2. Continuous Tracks Have Changed the World. Cat. 2008-09-29.
  3. Continuous Tracks Have Changed the World. Cat. 2008-09-29.
  4. Continuous Tracks Have Changed the World. Cat. 2008-09-29.
  5. Continuous Tracks Have Changed the World. Cat. 2008-09-29.