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This study presents the structure and principles of operation of the control system for a bucket conveyor operating in a jig preparation plant. The idea of controlling the conveyor speed is to maintain constant, nominal filling of the buckets, and thus achieve a constant mass of material on the conveyor. As part of the completed task, a new control algorithm was developed and implemented to increase transport efficiency. Simulation and industrial test results were analyzed, in which the traditional PID controller was replaced with a fuzzy controller, which enabled control error reduction, thus achieving better control quality.

This paper presents the problem of the operation of gear transmissions in the context of ensuring appropriate lubrication conditions. Damage caused by improper lubrication was discussed. Attention was drawn to the issue of oil contamination. Furthermore, a method for determining the thickness of the oil film of gear wheel teeth was described. There was also performed an analysis of the lubrication conditions of sample gear transmissions of the load, manufacturing technology and surface roughness.

Longwall shearers’ haulage system of the Eicotrack type, used most often nowadays, is presented in this article. Its disadvantages, causing problems with a correct operation of mechanized longwall shearer systems, are discussed. The concept of the innovative Flextrack, which should reduce the occurrence of the disadvantages mentioned above, is described. A course and research results, connected with rig tests of the Flextrack haulage system functionality, are presented. Measurement results of wear and stresses, obtained for the Eicotrack and Flextrack haulage systems, are compared and presented. Based on an analysis of the obtained results, a modified version of the Komtrack haulage system was suggested and manufactured. This haulage system was tested in the field conditions, similar to underground conditions in a mine coal longwall. The obtained results confirmed its full functionality and lack of problems experienced in the case of the Eicotrack and Flextrack systems. At present, the Komtrack system is tested in a coal longwall in Piast coal mine, where comparative tests with the Eicotrack system are conducted. The big part of the results presented in this article was developed as part of the research project KOMTRACK jointly implemented by KOMAG Institute of Mining Technology, AGH University of Science and Technology, Łukasiewicz Research Network—Cracow Institute of Technology, Specodlew Innovative Foundry Company and Polish Mining Group Inc., co-financed by the European Regional Development Fund (Contract No. POIR.04.01.04-00-0068/17).

The article provides a discussion on a methodology intended for testing of power transmission systems featuring an innovative highly torsionally flexible metal clutch patented by the co-authors of this paper. What this methodology takes into account is the amplitude and frequency analyses discussed in the article, as well as a sensing system based on diverse piezoelectric and magnetic phenomena, the Doppler effect, etc. Both contact and non-contact (laser measurement) methods were used during the tests. The purpose of the tests conducted at the stand, originally designed by the authors in accordance with the methodology proposed, was to evidence that using the innovative and patented, highly torsionally flexible metal clutch makes it possible to reduce the vibrations of multi-stage toothed gears, consequently reducing the forces affecting the gear bearings and those acting at the tooth space, which is to enable the service life of individual components of the power transmission systems intended for mining scraper conveyors to be significantly extended. Based on the studies and analyses performed by the authors, one can observe and conclude that the methodology proposed in the paper makes it possible to use an example of a relatively complex power transmission system in order to examine the relationships between the processes at work, i.e., the decline of the linear vibrations of the gear housing (which is undoubtedly positive in power transmission systems) at the expense of increasing torsional vibrations of the innovative clutch, the latter not to be considered unfavourable to users in the case analysed.

The paper presents how an important aspect of introducing new machines, especially in the mining industry, is testing a prototype under laboratory conditions. For this purpose, advanced methods of analyzing the vibrations of a drive system equipped with an innovative prototype of a flexible torsion clutch are presented. The main goal is to present a comprehensive method for analyzing vibration signals in various dimensions of the signal analysis. As a result of this approach, it can be seen how much important information about the tested clutch can be obtained by using various analysis methods in terms of time–frequency distributions or order analysis. To emphasize the differences in the functioning of the tested clutch and the possibility of monitoring these differences on the basis of the observation of residual processes, such as vibrations, the results for the flexible and locked clutch are compared.

This article provides a discussion of the results of studies on the original system condition monitoring of a three-stage transmission with a bevel–cylindrical–planetary configuration installed in an experimental scraper conveyor. Due to the high vibroactivity of gear transmissions operating under the impact of a scraper conveyor’s chain drive, these unwanted effects of machine operating vibrations were assumed to be applied. For purposes of the study, vibrations were measured on the driving transmission housing in an idling scraper conveyor. The main purpose of the study was to establish the frequencies characteristic of the gear transmission, and to determine whether it was possible to run vibroacoustic diagnostics of the same transmission under conditions with a considerable impact of the conveyor chain. An additional cognitively significant research goal was the analysis of the dependence of the diagnostic utility of the signal depending on the sensor mounting point. Five different locations of three-axis sensors oriented to the next stages and various types of gears were determined, as well as places characterized by high spatial accessibility, which are often selected as places for measuring the vibration of gears. Using MATLAB software, a program was written that was calibrated and adapted to the specifics of the measuring equipment based on the collected test results. As a result, it was possible to obtain a multidimensional data interpretation of vibration signals of system condition monitoring of a three-stage gear transmission operating under difficult conditions. The results were based on signals registered on the real three-stage gear transmission operating under the impact of a scraper conveyor’s chain drive.

The main objective of the study was to demonstrate the possibility of replacing the materials of domestic and foreign production currently used for chain drums with alternative materials. ADIs were selected as materials that may replace the cast steels used so far. L35GSM cast steel, commonly used for mining chain wheels and austempered ductile iron, conforming with the requirements of EN-GJS-1400-1 quality grade were subjected to wear tests. On the basis of the experimental studies it has been observed that for almost all the combinations of destructive factors considered, the ADI in question was characterised by a wear resistance better than that in the case of the L35GSM cast steel used so far. In addition, it has been found that the ADI has favourable features predestining it for use in the production of chain drums for armoured-face conveyors.

During an in-situ operation of machines, used for the exploitation of energy raw materials, a damaging impact of the environment on the components of these machines is experienced. The action of degrading factors is mostly shown in the form of a clear synergistic effect. In particular, this effect can be seen during an exploitation of driving elements of scraper conveyors, used as one of the basic machines in the hard coal mining process. In the article, the subject–matter, connected with an operation of sprockets in scraper conveyors, is presented. Special attention is paid to a mutual reaction of the mineral abrasive and the presence of mine water. The main objective of the research work was a determination of the interactive component of the factor causing an abrasive wear–quartz abrasive connected with the associated action and the factor intensifying electrochemical corrosion–water with and without the NaCl salt content. Experimental tests were conducted in the conditions similar to the reality, with the use of a test rig in the form of a short scraper conveyor. Within the framework of the test abrasive wear rates for the case of the abrasive presence itself and a mixture of the abrasive, salt and water were determined. Based on the obtained results, it appears that there is a synergistic impact of abrasive–corrosive mixtures on the wear of the surface layer of the chain sprockets under testing, and also, the causes of the interactive component values in the function of hardness and maximum strength of the materials under investigation are presented.

The paper presents the results of tests of wear of hardened wear-resistant steels in the presence of quartz, coal and coal-mineral abrasives of a differentiated ratios of each component and in the case without abrasives. The tests were carried out on a ring-on-ring test stand. Volume loss was the parameter used to characterize the wear level. Based on the Scanning Electron Microscopy (SEM) observations, different mechanisms of surface destruction depending on the type of abrasive were found. For the quartz abrasive, it was shown that the quartz grains cause micro-cutting, but surface cracks also appear that further transform into shallow holes. In the case of mixtures of quartz with coal, the surface was micro-scratched by quartz grains, but some of these grains were hammered into the surface, what was favoured by the presence of coal fractions. In the case of coal abrasive, traces of single cutting were observed, as well as unremoved scratches formed at the sample grinding stage. Based on the wear observation, two models of steel surface wear in the presence of coal and coal-mineral abrasives were determined.

In correctly functioning maintenance systems it is most important to prevent possible failures. A reduction of the vibroacoustic effects accompanying the operation of machines and equipment, including transmissions, is among the factors that lower the probability of a failure. The paper presents the results of the research on the impact of operational factors on vibroacoustic conditions of transmissions. The factors covered by the analysis included a change in the mating conditions of gear wheels associated with the wear of tooth surfaces, operation of transmissions in subharmonic conditions of the main resonance and the temperature of the lubricating oil. The study demonstrated that it was possible to reduce the vibroacoustic effects generated by gear transmissions by changing the conditions of their operation. Based on the results obtained, it has been found that the operation of gear transmissions in accordance with the sustainable development principles requires technical services to take active measures consisting in the search for optimal operating conditions in terms of the vibroacoustic conditions.

This paper presents a general characteristic of a rig for chain wheel testing in the conditions reproducing the actual op-erating conditions of conveyor elements in the rolling and sliding motion. This test rig allows performing wear tests in the presence of an abrasive material, corrosive factors and additional dynamic excitations in the form of steel beaters. The paper also describes a methodology of abrasive wear tests of chain wheels that allows determining the value of the linear wear of chain wheels and presents the test results for the materials typical of armoured face conveyors.

The paper presents a designing scheme based on the main criterion of optimisation, which is to minimize the vibrations and noise generated by machinery. This concept takes into account the deterioration of the strength and operational properties of constructions, which should be brought to a satisfactory level by applying additional measures. The consid-ered design approach was examined on the example of the gearboxes, for which it is extremely difficult to achieve a noise reduction due to their highly advanced technology.