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Most heavy plant and machinery is a result of mankind’s wish to minimise the amount of labour required to complete a job, and to boost productivity. One important machine is the excavator. Excavators dig into the earth and lift it away, using a repeated movement of the boom arm, and the bucket or claw which is attached to the boom. The term excavator encompasses a wide range of earth moving equipment, ranging from the large dragline used as part of strip mining operations, to the miniature hydraulic backhoes which are used for landscaping.
The Steam Shovel
The first earth moving machine which did not rely on the power of man was the Steam Shovel, which was invented in 1839 by William Smith Otis. The Steam Shovel was operated using pulleys and cables to operate a bucket and arm. The introduction of this machine caused a revolution in the civil engineering and construction industries, as it was now possible to move large quantities of earth at great speed.
Sir W. G. Armstrong & Company
The world’s first partly hydraulic excavator was designed and built by Sir W. G. Armstrong & Company in 1882, and was used to remove earth during the construction of the docks at Hull in eastern England. Early hydraulic excavators used water rather than hydraulic fluid in order to operate the relevant parts of the machine. The machine was not technically fully hydraulic, but was a hybrid, as the bucket was controlled mechanically by the use of cables. This was a major drawback of this early design.
Kilgore Machine Company
The first real fully hydraulic excavator was designed and built by the Kilgore Machine Company in 1897. The machine used four steam cylinders to operate the bucket rather than cables. This gave it several advantages over conventional cable-operated excavators. The Kilgore machine was constructed almost entirely of steel, which made it extremely strong, and the engine featured cushioned cylinders which helped to eliminate damage caused by shaking or shock when the machine’s engine was working at high speed. This excavator was the forerunner to the excavators supplied by modern day plant hire companies.
Another benefit of the design of the Kilgore machine was the use of steam cylinders, which provided a range of action and motion which was far superior to any other excavator. The bucket could be moved horizontally and could easily manipulate and move rocks and other obstructions. In the Kilgore machine, all movements of the arm had equal power; this meant that rather than having to pull the bucket in order to clear the cut, the bucket could be withdrawn while under load. By applying power to all bucket motions, the bucket could also be shaken in order to dislodge any material which was trapped inside.
Modern Day Excavators
21st Century excavators have been fitted with many advancements in terms of technology and operator comfort. Electronic devices now provide the operator with diagnostic and operational information, which boost levels of safety and productivity. Many modern machines use bio-friendly oil, and have engines which produce reduced levels of emissions so that they comply with environmental standards. However, despite these advancements and modifications, the modern day excavator is designed, and performs, in a very similar way to its predecessors from the 1880s, moving earth and helping mankind build a better world.