Earth-Moving Machinery.

The annual amount of mechanized earth digging operations comes up to thousands of millions of cubic metres. It requires the employment of a great plant of powerful earth-moving machines, the excavators being the most important of them.

You should start on a construction job with a good deal of preliminary leveling the site. To carry out this work one must employ the earth-moving equipment.

Site preparation and excavation are the most fully mechanized of all operations in building construction. Most excavating machinery is heavy and slow moving and must be carried from site to site on special transporters. It is clear that the use of expensive mechanical plant requires careful planning and efficient site organization.

Plant for site preparation and excavation can be divided into four classes. First, machines which plane off a thin layer of soil and push it in front of them. Second, machines which plane off a thin layer of soil, at the same time picking it up and carrying it where required. Third, machines, which dig out soil by some form of a bucket, and load it for transportation into several vehicles. Fourth, machines designed specially for trenching by means of a number of buckets mounted either on a continuous chain or on a wheel.

In the first class are bulldozers of different types. A bulldozer is an earth-moving machine, which carries out its work with the aid of a blade.

A scraper, which belongs to the second class of earth-moving machinery, is simply a large box with an open mouth, dragged along the surface of the ground until it is full. It has a cutting edge that digs.

There are a variety of the scrapers, from small units to huge ones made to accommodate 30 cubic yards of soil and to absorb the power of two tractors while at work.

Revolving shovels belong to the third class of earth-moving machines. They appeared first in1835 in America. It was a part-swing shovel mounted on railroad tracks and powered by steam. They were slow and clumsy. In 1887 they were used to work on Manchester Ship Canal. A souse of wonderment they were called the “American Devils”.

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