Vol 60 Iss. 1

The Leningrad Mining Institute together with the Kizelugol Combine created an experimental frameless tractor for moving a train of mine cars on smooth horizontal and inclined rails. The tractor was manufactured in the central mechanical workshops of the Kizelugol Combine and in the autumn of 1967 passed successful factory tests.

The modes of realization of the coefficient of adhesion of smooth driving wheels with rails have been studied in detail. It is established that at constant locomotive speed and constant pressure of driving wheels on rails there is a strict dependence between wheel slip and the coefficient of adhesion .

Calculations of modern locomotives with smooth driving wheels are made separately for the conditions of operation in traction and braking modes at the highest loads, when slipping or skidding is especially likely. At train resistances or braking forces adjacent to zero values, the gravity of the locomotive causes a very large reserve of adhesion forces, and there was no necessity in the study of these modes. Obviously, therefore, it was assumed that the zone of elastic sliding passes through the origin of coordinates.

An experimental sample of a friction‑driven hoist was created and successfully tested at the LGI. The hoist is moved by a special traction device with smooth drive wheels on a vertical rail made of an I‑beam.

In the creation of efficient and economical vehicles for the mining industry, a significant place is given to traction devices that automatically adjust the pressure of the drive wheels on the rail depending on the realized traction force. One of the main advantages of these mechanisms is that the traction force in the interaction of the wheels with a smooth rail is created independently of the adhesion weight of the self-propelled vehiclevehicle.

At the LGI, the basic scheme (figure) was developed and the working design of the experimental prototype of a self-propelled cage for the Koelginsky marble quarry was completed.

Experimental studies of traction devices capable of being self‑oriented relative to the entry tip of the traction rail during movement are underway at the LGI. They are intended to equip locomotives with a mixed principle of operation, which are supposed to be used for mechanization of transport operations for delivery of people, equipment and materials along horizontal and inclined rail tracks.

In order to ensure the optimal mode of operation under any conditions, traction devices with unstable transmission ratio are equipped with a relay tracking system, which operates according to the deviation of the set angle and maintains the calculated value of the transmission ratio. It consists of a control object and an automatic regulator.

The Leningrad Mining Institute and the Telman Combine of Fine and Technical Cloths, in fulfillment of a contract on creative cooperation, have created suspended monorail tractors with automatic regulation of the drive wheel pressure on the rail depending on the train resistance or the required braking force.

Traction devices with automatic regulation of wheel rail pressure provide a given mode of adhesion of smooth wheels with rails regardless of the track profile and changes in external load, which allows them to be used to move loads in inclined mine workings with any inclination angles.

Traction devices with automatic regulation of the force pressure of traction wheels to the rail depending on the resistance to movement are considered in the works of V. S. Bersenev.

Studies of the field of application of traction devices with automatic regulation of drive wheel pressure on the rail have shown that mechanisms with elastic slip can be used not only in the creation of vehicles (self propelled skips and locomotives), but also in the design and construction of new friction drives for rotating parts of large units (cement kilns, mills, scrubbers, reactors, etc.).

At the experimental site of the trust “Chiaturmanganese”, a brake bogie for automatic speed control of mine trains on steep downhill slopes was tested, in which, to actuate the mechanical braking system, an articulated‑lever drive mechanism is used, providing reliable adhesion of the drive rollers with the side surfaces of the rail.

The crank mechanism in general is unquely determined by three independent parameters, for example, the following: the crank mechanism in general is uniquely determined by three independent parameters, for example: the crank radius r; the relative connecting rod length λ = l/r (where l is the connecting rod length); and the relative offset ε = e/r (where e is the offset). We shall consider these parameters as variables. Then their domains determine the region of variation of crank mechanisms as a whole. The pattern of variations will provide a visual representation of the changes in the kinematic and dynamic characteristics of the crank mechanism as its parameters vary, which makes it possible to select the appropriate mechanism according to given specifications.

As a result of the study of traction devices, a new, most appropriate design of a peripheral drive for pulp thickeners has been developed.

Plate conveyors in recent years are increasingly common at industrial enterprises in the USSR and abroad (FRG, Belgium, England, etc.). For example, in the mines of the Ruhr Basin they make up more than a third of the total number of underground conveyors (excluding face conveyors). In a number of cases, plate conveyors are the only acceptable means of continuous transportation of goods.

The traction devices developed at the LGI have one or two smooth drive wheels. The number of wheels, based on strength conditions, determines the possible traction force for given dimensions of the traction device.

The use of high-strength synthetic and steel cord belts has made it possible to significantly increase the length and productivity of belt conveyors. The length of individual belt conveyors abroad reaches 4 5 km, and productivity 20,000 t/h. There are projects of conveyors with two head drives with a length of 14 km.

When studying the working organ of the rowing-rotor loading machine to record forces on the oscillograph, a rheostat sensor was made and applied, which was mounted on a clock-type indicator head attached to the dynamometer and recording the change in the position of its spring.

At interaction of the working members of loading machines with a stack, the resistance forces of the latter to penetration and separation of some volume of material are of a random, stochastic nature. This makes it difficult to determine the necessary driving forces on the working member of loading machines. The existing calculation methods address the issues of interaction with the stack of the bucket working member of the lower gripper and paired raking arms. The continuous action working member of the upper gripper has been insufficiently investigated. The questions concerning the principal features of this member and its energy parameters are touched upon only in a few works. To some extent, this is due to the indeterminate nature of the motion of the said member when interacting with the stack, which makes it difficult to consider its kinematics, and hence the determination of forces in the links, not to mention the dynamics of loading...

Widely used as the main mechanical means of hydraulic hoisting systems, hydro‑elevators have to a large extent exhausted their possibilities. Further design and technological improvement only slightly changes their significant disadvantages: low efficiency, high energy consumption and small lifting height.

The main indicator of a mine loading machine is its technical productivity, which depends on many factors. These include, first of all, factors characterizing the machine itself and especially its working member: the principle of action on the stack, dimensions, shape, number of cycles per unit time. External factors have a substantial influence on productivity; they include the physical and mechanical properties of the material being loaded, the characteristics of the stack, the dimensions of the working, the organization and type of transport following the machine.

Novikov gears, due to their inherent increased load capacity, are becoming more and more widespread. However, the issues of bearing durability, as well as the strength and stiffness of the shafts in them, have not yet been studied. Therefore, the loading of bearings and shafts is either not assessed at all or is assessed only very roughly. This situation is explained by the certain specificity of force formation during the interaction of the gear elements in a Novikov gear and by the lack of proper research due to the insufficient study of the issue.

The task of structural studies of chamber feeders is to determine the most suitable forms of chamber parts and assemblies, as well as a rational design of the feeder as a whole.

A device for large‑scale graphic representation of wheel tooth profiles cut by the generating method has been developed. It uses a special template made of transparent sheet material (plexiglass), in which narrow slits are provided to scale corresponding to the contour of the cutting tool. On the lower plane of the template there are equally spaced parallel marks perpendicular to the mark coinciding with the pitch line of the rack.

When studying the input of material into the slurry pipeline by chamber feeders, two possible design schemes were used: with gravity and hydrodynamic feeding of material. The most appropriate design of chamber feeders is that with hydrodynamic feeding of material, as they better meet the conditions of operation of hydraulic transport systems.

A simple graphical method of determining the shape factor of wheel teeth used in calculations of bending strength of gears has been developed. The properties of the tangent to the parabola, which is inscribed in the contour of the tooth, are taken into account in determining the dangerous cross‑section of the tooth, usually considered as a cantilever bar.

Gear pneumatic motors belong to positive displacement type motors. The working chambers are the cavities, and the pistons are the teeth of the mating rotors. The cavities and teeth have complex shapes and participate in complex planar relative motions, making it difficult to understand the working processes of these motors.

The task of creating a flotation machine that meets modern requirements can be solved only under the condition of a rational design of the main components and their linking into a single complex, subordinated to the fulfillment of the required technological and technical‑economic performance indicators of the machine.

During bench tests of Novikov gears to identify their load capacity, it was possible to experimentally evaluate their efficiency. For this purpose, an electric motor balanced on support rollers was connected to a test bench with a closed power flow. The reactive torque of the motor was determined by its angular deviation in the steady‑state mode of operation; the power of the motor, in the closed circuit of loading gears, is spent only on overcoming the resistance to rotation.

For electronic modelling of working cycles of pneumatic machines, a relay switching device (RSD) has been developed and is being used. It serves for changes in the switching of the electronic model when solving problems described by different systems of differential equations over separate intervals of variable change.

The choice of optimal parameters of gears with Novikov gearing is a critical task in mining engineering, especially in the gears of underground machines, to the dimensions of which strict requirements are applied. Even greater difficulties arise when designing Novikov gears that would satisfy the requirements of high contact and bending strength of teeth. Reliable information about the experimental application of these gears in mining engineering is still insufficient. Moreover, the experimental data refer to individual gears made with different parameters, materials, and initial contours. They have been obtained under different load conditions. All this complicates guidance in the choice of optimal parameters of Novikov gears during design.

On the example of a vibrating loading machine, the method of calculation of acting loads in kinematic pairs of the eccentric drive of the vibrating loading chute has been developed. In this case, the graphical method of kinetostatic study is used, by means of which the values and directions of reactions in the joints are determined.

Modern methods of calculation of pneumatic hammers are based on the assumption that their working processes are in equilibrium, and the mass exchange during filling and emptying of the working cavities of the cylinder occurs in accordance with the regularities of the steady flow of compressed air.

Practical needs of bringing scientific research closer to production dictate the necessity of studying natural objects in natural (industrial) conditions. This requires a reversal of the classical vibration test bench‑object scheme, i.e. not the object being installed on the test bench (often it is simply impossible), but the object itself being transformed into a full‑scale research test bench by adding to it a vibration device consisting of a vibration exciter and measuring systems.

The efficiency of pneumatic rock drills, the durability and reliability of their work are largely determined by the lubrication of the rubbing parts. The studies carried out at the Pnevmatika plant have shown that under conditions of high dynamic loads, high sliding speeds of contacting surfaces and increased temperatures in the contacts, lubrication significantly affects the parameters of the drill, especially its torque, as well as the rate and nature of wear of its main rubbing parts.

Mine regulations of many countries contain requirements that single‑rope hoists intended for lowering workers must be equipped with safety catches for hoisting vessels. Existing safety catches, unfortunately, do not fulfill their main task, which is to provide fail‑safe braking or stopping of the falling cage (skip) in the case of breakage or detachment of the rope.

Developed at the Leningrad Mining Institute, with the participation of the Scientific Research Institute of Polymerization Plastics, the Okhta Chemical Combine, and the Donetsk Machine-Building Plant named after the 15th Anniversary of the LKSMU, the plastic grade PP-45 has found wide application as a lining for rope-driving sheaves of mine multi-rope hoisting machines.

In the present article with the help of the method of I. G. Bubnov – B. G. Galerkin an establishing (transitional to static) process of deformation of an elastic half-space due to the applied to its surface instantaneously and further in time not changing, asymptotically decreasing from the center, axisymmetrically distributed normal load – p is considered.

The main question that has to be solved in the design of any machine is the question of the forces arising in the links of the machine during its operation. The cause of force loading in crushing machines is the resistance of the material to crushing. Theories of crushing are designed to answer this basic question or to provide a quantitative estimate of the energy intensity of crushing.

One of the complex processes in hydraulic mines and coal preparation plants is water clarification. Volumes of water reuse in the technological process at hydraulic mines are measured in thousands of cubic metres per hour and depend on the adopted technology of extraction, transport, hoisting and coal processing.