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The article presents a study of the dynamic forces occurring in the chain of a rescue scraper conveyor during its steady operation. It describes the characteristics of the test stand in the form of a scraper conveyor for investigating dynamic forces in the chain, moreover, the results of these tests are presented. Based on the values obtained during the dynamic tests, the characteristic parameters of the above mentioned measurements were determined. [ABSTRACT FROM AUTHOR]

In mining plants (underground and on the surface), high-power machines are used. Electric motors and the gears driven by them have a specific cooling system as a flow system with an internal heat exchanger. The role of the heat exchanger is to collect the thermal energy generated during the unit operation. The refrigerant with the received thermal energy must be led away from the motor and gear unit, where it will be cooled. In the drives used in underground hard coal mines, water is the cooling medium, supplied through a firefighting pipeline. The water used for cooling is often discharged directly to the floor or to sewers, and further it is transported to the surface. The article presents a solution that uses tanks for cooling liquid with highly efficient air-water coolers in surface and underground applications. [ABSTRACT FROM AUTHOR]

The article presents tests on the possibility of using ultrasonic transducers for accurate distance measurement in hard coal mines. In order to check the impact of selected disturbing factors on the measurement results, test stands were built, and then a full cycle of measurements with the use of different transducers (AR30 and AR41), which were selected and pre-tested in previous research projects, was realized. The impact of such disturbing factors as airborne dust (coal, stone, lime and mixed dust), changes in temperature and humidity on the propagation of ultrasonic waves, amplitude and measurement accuracy was investigated. The tests were preceded by theoretical analysis. It was found that the transducers selected for the tests had a sufficient accuracy and range, so they can be used in the devices planned to be designed, allowing for the determining of the location of a roadheader in hard coal mine roadways, taking into account technical and legal restrictions. It was also specified which disturbing factors should be compensated and what methods and parameters of this compensation should be used. [ABSTRACT FROM AUTHOR]