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Vintage steam shovel
See also Front Shovel & Hydraulic Excavator

Since its creation, the shovel has evolved into many forms. Beginning as a steam-powered device, inventors and manufacturers continued its development for the two centuries after its birth.

The result is a long line of machinery, many of which have crossed industries and become multi-functional and crucial to a majority of applications. The steam shovel, a simple device used to lift dirt, has branched off first as cable excavators, and then as hydraulic excavators. The wide variety of excavators is evidence of the impact shovels have had on the industry.

The shovel has also served as the basic prototype for other equipment—stripping shovels, draglines, and bucket excavators, all of which have play important parts in how dirt is extracted from the earth.

Contents

[edit] History

[edit] Otis' Steam Shovel

The shovel is one of the earliest pieces of earthmoving equipment to appear on the horizon. It originated in the form of William S. Otis’s steam shovel. Otis’ invention arose from an urgent need to produce a machine that would enable his construction firm, Carmichael & Fairbanks, to succeed in its contract. The firm of Carmichael & Fairbanks had agreed, in a railroad construction contract, that the railroad would be completed within certain time constraints, or the firm would suffer penalties.

The firm was using horse-drawn carriages and brute force to move volumes of earth for the foundation of the railroad. Worried that the slow effort would not enable him to keep within deadline, it occurred to Otis that steam engines, which had been around since the 1800s, might produce a lifting motion that would eliminate animal and manual labor.

With the help of his engineer friend, Charles H. French, Otis built the first steam-powered shovel in Canton, Massachusetts. The shovel consisted of a one-cubic yard (0.8 m3) dipper that swung half-circle. The 1835 invention was the beginning of a long line of derivatives to come.

It took some time before the Otis Shovel could fully be embraced, as Otis had patented his version. At the time of his death at the age of 26, family members were reluctant to make his patent available.

[edit] 19th Century Growth

In late 1800s, manufacturing shovels began to pick up in a big way. Inventors were experimenting with this early prototype. One to have success was Ralph R. Osgood. Between 1875 and 1877, he patented his own lines, which were to later be acquired by shovel giant Marion Power Shovel Co. in the 1950s.

The first revolving shovel was produced by Whitaker & Sons in 1884, a company in England. Its success did not translate across the oceans.

[edit] Captain Thew's Shovel

The shovel evolved with the help of Captain Richard P. Thew. Thew owned a boat that sailed the Great Lakes to collect iron ore. The ore collected was brought to steel mills in and around Cleveland. This commission-based job meant that the more he was able to produce, the more he was paid. Thew used rail-mounted shovels but they were slow and were not suited for the docks. To counter this, he produced a shovel with a 360 degree swing. It could dig materials from any such direction and proved to be less destructive as the others.

The company for which Thew collected iron ore was so impressed that it offered to purchase Thew’s shovel. His shovel was a hit with steel companies around the area and he thought other industries might have use for it as well. Thew founded the Thew Automatic Shovel Co. Inc. in 1899. The company drew a lot of attention and the shovels were used for mining, building canals and tunnels, and digging holes for construction.

Eventually teaming up with another company, Lorain, they produced a number of successful models: including the Model O crawler shovel and the Lorain 75, a crawler-mounted shovel consisting of a 40-foot (12-m) boom and 12-foot (3.7-m) working radius in 1925.

[edit] Evolution in the 20th Century

By the 1920s, shovels were changing in a big way. Previously, they were mounted on rail cars. Manufacturers saw the benefits of making them more mobile, so they were mounted on crawlers or wheels. Companies began emerging quickly during this time. Bucyrus and Erie both produced successful shovels. Erie launched its Type B, a railroad ditcher steam shovel, in the 1920s.[1]

It was no match to the Bucyrus 80B, an electric-powered shovel produced in 1925. This pointed towards another trend that emerged. Shovels were no longer powered by steam, but gas and oil instead.[2]

[edit] Features/How it Works

The earliest shovel was rail mounted but later versions could be wheeled or mounted on crawlers for more mobility. Changes also included evolving from steam-powered to oil- or gas-powered. Many of the features of the first shovel have merely been improved upon, such as the slew. The first machine was limited in its swing, but since manufacturers have devised a way to make the arm capable of a 360 degree swing. The bucket can also be altered to lift a certain weight of materials, usually measured in cubic yards.

The arm of the shovel, also known as the boom, is controlled by switches and gears. This can be done by hydraulics, pneumatics, or in as in the cable excavator, by cable wires. The bucket strikes the earth and scoops the material. In some situations, there is a dump truck or other vehicle for the purpose of dumping. In stripping shovels, the shovel is capable of breaking through hard rock for the purpose of uncovering raw materials or minerals.

[edit] Types

The way shovels have evolved since Otis’s invention can be seen in the dozens of varieties have materialized over the course of two centuries. They have taken many forms, but the most important are listed below.

[edit] Cable Excavator

The first cable excavator originated in the form of the shovel but evolved when the mining industry required heavy-duty equipment. Cable excavators extract dirt by the pulling of wire ropes or cables. The Bucyrus 120-B, produced in the 1920s, answered the demands of mining quarries with its capabilities. The cable excavator was made almost obsolete and suffered a steady decline when excavators were made hydraulic. Manufacturers such as Bucyrus and P&H still produce cable excavators and they are used mostly within the mining industry; however, they are no match for the stripping shovel or walking dragline.

[edit] Hydraulic Excavator

The hydraulic excavator overtook the cable excavator because it was cheaper, faster and more productive. Using hydraulic oil to function the arm and bucket, the hydraulic excavator is one of the most popular machines. The earliest record of a hydraulic shovel appeared in 1882, by a British Company called Sir W.G. Armstrong & Co

The very first successful hydraulic excavator was the TU, produced in 1951 by Poclain. Not able to produce full revolutions, it achieved digging operations with the help of a pump. Poclain improved its version with the TY45, an excavator that could revolve.

[edit] Stripping Shovel

Stripping shovels are used to strip away hard materials and rock to uncover materials. they differ from the cable excavator in its height and capability. More suited to extract hard materials in heavy-duty operations, mainly mining, it is embraced for its size and power. It is also more advanced in that it moves forward on the excavated surface to continually extract materials. Stripping shovels, such as the 15,000-ton Captain shovel, are among the largest in the world.[3]

[edit] Common Manufacturers

[edit] References

  1. Sheryn, Hinton J. An Illustrated History of Excavators. Ian Allan Publishing: Shepperton, 2000.
  2. Haddock, Keith. The Earthmover Encyclopedia. Motorbooks, St.Paul, 2002.
  3. Haddock, Keith. The Earthmover Encyclopedia. Motorbooks, St.Paul, 2002.