Coal-Cutting Machine

a machine for producing a cut in a seam of a mineral (usually coal) in underground operations. The cut facilitates the breaking of the remaining part of the layer by means of mechanical devices or explosives. Coal-cutting machines can operate in gently sloping, sloped, and steep seams.

The first attempt to mechanize coal cutting was made in Great Britain in 1761, when M. Menzies received a patent for a mechanical cutting device in the form of an iron miner’s hack, mounted on a frame and driven by rods and levers from the surface of the shaft. In 1852, S. Voring patented a disk working member for a coal-cutting machine that had chisel teeth on its periphery and that was rotated by two workers through a system of levers and gears. In the mid-1850’s rod-type coal-cutting machines appeared in Great Britain, first with pneumatic and then—in 1887—with electrical drive. The first Gartsheri chain (the working member was a coal-cutter jig, with a toothed cutting chain that moved in its grooves) was made in Great Britain in 1864 by V. Baird. In the 1880’s chain coal-cutting machines of the Breast type, with a reciprocating jig, and in the 1890’s the Shortwall type, which made cuts 2 to 2.5 m deep, were made in the USA. The former type was moved to the pit face by hand, and the latter had its own engine. In 1913, 517 million tons of coal were mined in the USA and 292 million tons were mined in Great Britain (49 percent of the coal mined in the USA was mined using 15,236 coal-cutting machines; 3,518 cutting machines were in operation in Great Britain, cutting 7.7 percent of the coal).

The use of pneumatic coal-cutting machines in Russia dates to the 1870’s (they were percussion machines imported from Great Britain) on the Grushevskii anthracite and Nikitovskii coal mines of the Donbas. In 1913, 1.7 percent of the coal in the Donbas was mined with coal-cutting machines.

The first production of coal-cutting machines in the USSR was set up at the Gorlovskii plant. In 1927 the DL (Donets Light) electric coal-cutting machine was produced; in 1928, the DT (Donets Heavy); and in 1932, lot production of the DTK (Donets Heavy Cable) coal-cutting machines, which moved along the pit face by means of hauling cables, began. The GTK (Gorlovskii Heavy Cable) machine, with a 22- to 25-kilowatt (kW) motor; the GTK-35, with a 35-kW motor; the automated GTA-1 and GTA-2 (Gorlovskii Heavy Automatic), and the GMA (Gorlovskii Powerful Automatic), with a 41.5-kW motor (1940); and the light BSh (Jig Drift) electrical machine, for the driving of preliminary workings in coal, were produced later. Automatic coal-cutting machines were produced experimentally. The MV-60, KMP-1, and KMP-3 series of high-powered machines, which had higher tractive effort on the cables, powerful motors (47-65 kW), and remote control and which made it possible to make cuts in coal beds of almost any thickness and toughness, were developed during the Great Patriotic War. These machines, along with the portable GTK-3M coal-cutting machine, served for a long time as the basis for manufacturing cutting-loading machines and coal combines. The GTK-35 and MV-60 had a feed unit with a ratchet gear, ensuring graduated regulation of the feeding speed, in the former from 0.2 to 0.8 m/min and in the latter from 0.23 to 0.92 m/min. In the GTK-35 this was accomplished by changing the oscillation arc of the leading ratchet by increasing or decreasing the length of the ratchet-gear crank; in the MV-60 it was done by changing the angle of revolution of the ratchet through a shift in the position of contact of the leading ratchet with the tooth of the wheel.

The KMP-1 and KMP-3 coal-cutting machines are equipped with friction fluctuating speed regulators, which provide stepless regulation of the speed of operation of the feed from 0 to 0.86 m/min (the KMP-1) and from 0.3 to 1.4 m/min (the KMP-3). The cutting-loading machines based on these cutters are used in combination with explosive breaking of coal.

The working member of a coal-cutting machine is a coal-cutter jig, which consists of a guiding frame and a cutting chain, made of knuckles with teeth mounted on them, which moves in the frame. A distinction is made between one- and two-cleat cutting chains depending on the number of cleats connecting the knuckles. In the absence of cleats, when the knuckles are connected by hinged joints, the chain is called cleatless. Modern coal-cutting machines are equipped with devices for mechanical sumping of the jig in the layer and its removal from the cut, devices for removing coal dust (gummers), and sprinkling devices for slaking dust during cutting. The conveyor part of a coal-cutting machine is hydraulic and ensures relatively smooth movement of the machine during cutting and stepless regulation of the conveying speed from 0 to 2.8 m/min (in the Ural-33 machine). The coal-cutting machine is moved along the pit face by means of cables wound onto a drum. The transverse-jig Ural-33, which bears the State Mark of Quality and which has an 88-kW motor and a coal-cutter jig 2 m long and is the basis for the manufacture of coal combines, is the best domestic coal-cutting machine. In the USA, all-purpose coal-cutting machines for making arc-shaped cuts in any plane when driving shafts or for extracting coal from short faces, are widely used. The various types of cutting machines include cutting-loading machines (for cutting and loading the cut coal on conveyors in gently sloping seams 0.8 to 1.8 m thick, with a stable roof) and cutting-breaking machines (for cutting and extracting coal). (The classification of cutting machines according to various indicators is shown in Figure 1.)

The all-around mechanization of extractive work in the mines of the USSR with the use of mining combines and complexes has limited the use of coal-cutting machines to extracting hard and tough coals (such as the Kizel region in the Urals), for the extraction of which reliable coal combines have not yet been created.

Figure 1. Classification of coal-cutting machines