Gear pneumatic motors belong to volumetric type motors. The working chambers are the hollows, and the pistons are the teeth of the mating rotors. The troughs and teeth have complex shapes and participate in complex planar reciprocal motions, making it difficult to understand the working processes of these engines.

Three-link screw mechanisms converting translational motion into rotational motion are widespread due to their compact design. They are used in pneumatic drilling hammers and perforators, the annual production of which for mining and construction industry only in our country counts' hundreds of thousands of units. Development of the national economy puts forward the tasks of increasing the productivity of this equipment and increasing the efficiency of mechanisms perforators.

Pneumatic motors are used only in the mining industry and, despite this relatively narrow area, in their production there is an economically unfavorable multiplicity of models with the same operating parameters, but different sizes of the active part (rotors, pistons). For example, G I. Petrovsky plant (Donetsk SNH) serially produces gear pneumatic motors type BSH2-1-5 and PSH-7A with the same operating characteristics (pressure 3.5 kg/cm^2, power 7 hp, compressed air flow rate 6.,8-7 m3/min), but different sizes of rotors: the first has a rotor width of 150 mm and inter-center distance of 100, 75 mm, the second respectively 120 and 145.3 mm. Darasun plant (Chita SNH) and the Communist Plant (Krivoy Rog) serially produced also identical in operating characteristics (5 kg / cm^2; 10 hp; 10 m3 / min) piston engines DR-10 and MP-5. But the diameter and stroke of pistons in the DR-10 engine is 101X62 mm, and MP-5 POX 80 mm. These are not single examples.

Actual processes in pneumatic engines of mining machines proceed at incomplete expansion of air. The main reason for releasing still workable air into the atmosphere is the need to limit the temperature drop inside the cylinder to a certain limit to prevent solidification of lubricant and ice formation.

Pneumatic motors and tools, widely used in underground work, increase the compressed air consumption if its pressure is increased. Working at higher pressures is associated with more intensive wear of pneumatic equipment and especially rotary pneumatic motors. Automatic pressure regulation directly in front of the consumer could help to eliminate these disadvantages, but produced pressure regulators are bulky, heavy, so it is difficult to use them in underground conditions.

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 technical problems of mining industry development is the problem of transportation of large volumes of rock mass. The solution of this problem should provide a significant increase in the productivity of transportation plants. The newest transport equipment should satisfy a number of other requirements, the most important of which are: a) increase of labor productivity at transport works; b) increase of reliability of transport work and complete elimination of delays in work of excavation machines due to transport; c) decrease of cost of transportation of bulk cargoes; d) all possible introduction of automatic control of transport complexes; e) increase of service life of transport mechanisms and replacement of the most expensive and scarce materials used for their manufacture; f) decrease of the cost of transportation of large volumes of rock mass. Of exceptional importance is the creation of productive and reliable installations for transportation of huge volumes of bulk cargoes during large hydraulic engineering construction and at modern open-pit mines equipped with the latest mining machines of high productivity and power.

The process of scooping or gripping with a bucket the rock mass, which is to some extent in a disturbed state of adhesion between the particles, is one of the links in the chain of processes for the extraction of minerals. However, it has not received sufficient coverage in the technical literature. Related areas, such as the theory of soil cutting, are also comparatively poorly developed. Research works on loading machines do not go further than the registration of the mode of operation of machines, do not investigate the compliance of the machine to the face, do not analyze the individual stages of loading and therefore cannot give justification to the theoretical concept of the loading process, the magnitude and nature of possible forces and calculation methods of newly designed loading machines. Experiments with models of the elements of the working elements of loading machines (published so far) are only the first steps in the systematic study of the scooping process, since the conditions of the experiments cannot correspond to the actual operating environment of loading machines.

The problems of kinematics and dynamics of the shovel of loading machines are represented by several works of domestic technical literature and few substantial foreign works. Among them the most interesting are the articles by S. G. Kalmykov, who compared the kinematics and dynamics of three types of rolling handles (shovels), determined the force in the handle chain and the power consumed by loading machines, and K. A. Lohanin, who justified the design changes in the loading machine associated with the replacement of pneumatic motors with electric ones. At the same time, K. A. Lokhanin considered the kinematics and dynamics of the shovel. The starting point of these theoretical studies is the independence of the number of revolutions of the motor shaft from the load during the shovel movement. The result of this simplification, which makes us abstract from the relationship existing in any engine between the load and the number of revolutions, is a huge error in the calculations.