(earthmoving machines), machines for earthwork during the erection of industrial and public buildings, the construction and repair of railroads and highways, the laying of underground communications, and the mining of minerals. Excavating machines are used for working soils of all categories, including frozen, rocky, and swampy ground, and mineral deposits. Excavation-transport machines (used for the working and shifting of soil) and excavators are also classed among the basic excavating machines.
Excavation-transport machines, including bulldozers, trailer scrapers, semitrailer scrapers, self-propelled scrapers, graders, and autograders, have working members that cut up the ground in layers and can transport the soil for distances ranging from several meters to 5 km. Grader-elevators, which dump the soil into a dumping ground or transport equipment, are also in the same class as these machines.
Excavators (mechanical shovels and multibucket excavators) are the most commonly used types of excavating machines. Mechanical shovels have interchangeable equipment with which it is possible to work the soil above or below the parking level of the machines and to load the soil into the transport equipment or pour it into a dumping ground. Multibucket excavators (rotary bucket and chain bucket excavators) are used mainly for earth work in light and medium homogeneous soils. Rotary bucket excavators used in con-junction with dumping spreaders constitute continuous-motion excavating-transport complexes having high capacities of up to 12,000 cu m per hour. Dumping spreaders are self-propelled fully revolving structures with belt conveyors for moving the soil to the dumping location or for loading the soil from one level to another. The soil can be transported up to 250 m while simultaneously being lifted 70 m. These complexes are used in open-cut mines and in construction-materials quarries.
Soviet excavating machines are exported to many coun-tries of the world. Further developments in excavating machines are aimed at increasing their capacities, reducing costs and the amount of metal used, increasing reliability and durability, standardizing assemblies and parts, automating controls, and developing the widespread use of various types of mounted equipment.
REFERENCESMashiny dlia zemlianykh rabot: Teoriia i raschet, 2nd ed. Moscow, 1964.
Krutikov, I. P. Ekskavatory. Moscow, 1964.
Zemleroinye mashiny nepreryvnogo deistviia: Konstruktsii i raschety. Moscow-Leningrad, 1965.
E. A. KAMENSKAIA and S. A. SOLOMONOV