Vol 34 Iss. 1

General remarks Although internal combustion engines began to be used in industry long ago - explosive engines about 70 years ago, slow combustion engines about 50 years ago - but their theoretical study lagged behind, as it often happens when introducing new ways of technical progress.The main problem of theoretical research in the field of heat engines in general is to determine the maximum values of thermal efficiency of engines at work without heat losses caused by side causes, not by the principle of conversion itself.

In the practice of design and operation of mine electric locomotive traction is very important is the correct solution of the question of choosing the size of the train. In modern production practice, the solution of this question is essentially reduced to the choice of the coupling weight of the electric locomotive. Indeed, in spite of the fact that theoretically the optimum train size can vary within wide limits with an interval equal to one car, the coupling weight of the electric locomotive is taken not as required by the calculation for this train, but the nearest to the calculated one according to the standard. The final size of the train is usually taken from the condition of the maximum weight of the train for the selected electric locomotive size. Since there are only three standard values of the coupling weight of rolling electric locomotives, the same coupling weight of an electric locomotive is inevitably adopted for a very wide range of optimal train sizes.

The application of hydromechanization in the development of coal deposits by underground works, proposed by V. S. Muchnik, has set a number of new tasks for mining science. One of the biggest tasks in this area is the study of factors determining the effectiveness of the impact of water jet on the coal or rock massif, because only as a result of such a study is possible both to improve the process of hydraulic destruction of coal and rock (hydraulic stripping), and to expand the area of rational application of hydromechanization. The question of energy consumption of the process of coal destruction by water jet is of no small importance. Some of these works were carried out in the laboratories of the Leningrad Mining Institute.

Manual labor in the production of exploration and engineering-geological research still occupies a large place. Among these works, manual drilling of boreholes in the exploration workings is of no small importance. Labor productivity in manual drilling is low. For example, for sinking a borehole depth of 1.5 meters and a diameter of 35 mm in rocks of medium strength is spent 3.14 man-hours. The use of existing mechanisms for borehole drilling in exploratory excavations in some cases is impossible due to the lack of energy sources. Large volume, labor intensity and high cost of manual drilling urgently require mechanization of this process.

When preparing ores for beneficiation, as well as in the construction of various structures are widely used machines for crushing large pieces of rocks. Among them a prominent place is occupied by the so-called jaw crushers, in which pieces of rocks are crushed by periodically pressing on them two rectangular jaws - swinging and stationary.For the normal operation of such a crusher is necessary that when pressing the jaws on a piece of ore, the latter is not pushed upward by them, but wedged between them. This is not possible at any angle between the jaws, but only at angles smaller than some of the largest angle.

The development of reliable safety devices to catch the falling stand at the breakage of the hoisting rope is one of the issues that have not received to date a satisfactory design solution.Development of the design of reliably working parachutes to stop the falling stand is necessary in connection with the transition of mining operations to the development of deep horizons and associated with this increase in the speed of movement of stands.

There is an opinion about the inevitability of unstable operation of local ventilation fans in the presence of a hump in their characteristic. When determining the mode of operation of the fan in the network does not take into account the leakiness of the pipeline, which introduces some features in the calculation methodology, which is not sufficiently developed and not brought to a form convenient for practice.To clarify these issues and made an attempt to develop a methodology for determining the mode of operation of the local ventilation fan and its stability.

About one-fifth of the coal in the Soviet Union is mined with pneumatic jackhammers, and the mechanization of underground work in the ore industry is carried out almost exclusively with compressed air power. In addition to jackhammers and drilling hammers, a lot of various mining equipment with pneumatic drive has appeared in the face and at the site nowadays. With the wide application of shield system of coal mining at powerful steeply falling seams, as well as the system of development by horizontal layers, the number of upward workings, which are used for ventilation, coal transportation, fixing timber, etc., is sharply increasing. For sinking of such workings the air-drilling machines are more and more often used.

In practice of development of coal and ore deposits and in non-metallic mines there is a necessity in construction of rope cargo bremsbergs with variable inclination angle. At modern coal mines bremsbergs at inclination angles up to 18° and at relatively significant productivity are equipped with belt conveyors. In mine workings, the angle of inclination of which exceeds 40°, the descent of minerals, as a rule, is carried out on fixed chutes (grates).

General information. Formulas, which are used for energy calculation of pneumatic motors, are derived for ideal machines, and in the experimental verification are provided with correction factors.Already in the very method of obtaining calculation formulas contain contradictions: first, considering the ideal machine instead of the actual, researchers depart from reality, and then, introducing experimental coefficients, are closer to reality. The deviations from reality are sometimes so strong that the correction factors take the form of complex functions that are difficult to determine precisely.

One of the most important tasks of checking and adjusting the braking device of mine hoisting machine is to determine the deceleration at emergency braking.According to safety rules, when lowering a loaded vessel, in case of emergency stop, the deceleration should be at least 1.5 m/sec² and when lifting - no more than 5 m/sec². Consider the method of calculating the pressure in the brake cylinder at emergency braking.

Powerful modern hoisting machines perfectly serve mines up to 800 ts depth. Lifting machines for mines of greater depth (not counting lifting machines with friction pulleys, which have known disadvantages) should have either drums of larger sizes than currently manufactured, or the possibility of using a double-layer coiling rope on the drum. New machines, unlike the existing ones, should have less weight and better qualities.

Vibrational phenomena are now widely used in all areas of engineering. The first attempts to apply vibrations for destruction of coal massif are resonance and vibration jets. Daily experience testifies to the effectiveness of shock application of load for destruction of brittle materials. Coal by nature is relatively brittle, and it is quite natural to apply percussive shearing of it during excavation.

December 27, 1955 died a major Soviet scientist, head of the Department of Mining Electrical Engineering of the Leningrad Mining Institute, Honored Worker of Science and Technology of the RSFSR, Doctor of Technical Sciences, Professor Felix N. Shklyarsky. Shklyarsky was born in 1883. He graduated from two higher educational institutions: the St. Petersburg Mining Institute in 1911 and the St. Petersburg Electrical Engineering Institute in 1917. Then for a number of years he worked as an engineer in Donbass, holding the positions of mining supervisor, ventilation superintendent and mine superintendent.