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This article presents a description of design work for newly created centrifugal fans. This was done based on the example of an innovative solution that uses a change in impeller geometry. In the described solution, this is achieved by shortening and lengthening the impeller blades. The development of a technical solution with such properties requires a change of approach in the design process compared with classic solutions. Therefore, the following text describes this process from the concept stage to demonstrator tests. The principle of operation of such a solution is presented and the assumptions made based on analytical calculations are also described. The text also shows a 3D model of the centrifugal fan with variable impeller geometry, made with the help of computer aided design (CAD) tools. In the further part, numerical calculations were made on its basis. The finite element method (FEM) calculation made it possible to verify the structural strength of the project and its modal properties as well as to verify flow parameters, thanks to the use of computational fluid dynamics (CFD) calculations. The next step describes the procedure for testing centrifugal fans with variable rotor geometry, which is different from that of fans without this feature. The next part presents the results of research from the tests carried out.

The testing and inspection of fans is a crucial task at the stages of designing and prototyping as well as in terms of future exploitation. In case of machines performing rotational movement, the scope of research is very broad and concerns strength tests, vibration diagnostics, acoustic test, and flow tests. The article presents the issue of studying vibrations of chosen elements of a fan with special regard to the casing and flow tests of the fan itself. The tests were carried out both on the actual object and numerically.

The article describes the necessity of taking into account the welding procedure used in the process of designing carrying structures. It also presents the most common errors which the constructor might make during the process of designing welded joints. What is more, the mistakes discovered during installation works carried out on a real object are presented. The article also informs how to avoid such errors in the process of designing.

This article presents a research approach that enables the assessment of the technical condition of complex technical objects. The main emphasis is placed on the load-carrying structures of these objects. The procedure applying experimental research techniques and computer computations using the finite element method is described. The combination of the two techniques assesses the technical condition of the structure. The described approach is presented using the example of two objects.

The modal analysis of technical objects undergoing variable load intensity is an important task, thanks to which the safety in terms of resonance vibration phenomenon can be measured. This paper concerns the aspects of testing the new WLS series fans, used for local mine ventilation, which provide safer underground conditions resulting in more efficient work. The use of numerical methods in the calculations of natural frequencies and the comparison of numerical and experimental results calculated with the use of operational modal analysis have been emphasized.

The fundamental parameter which determine the design of the structure and proofs its safe operation, is list of dead and live/operational loads together with its distribution. That defines the stability of unit. In case of mining machinery, due to its specific layout and enormous size, occurrence of the stability loss can result in catastrophic failure. In the paper, authors present investigations of the stability loss of discharge bridge operating with bucket wheel excavator. Authors, step by step, present the definition of overturning edges, weighing and balancing process. Moreover, numerical simulations and experimental testing of the structure are presented. On the basis of acquired data, cause of the stability loss and assessment of influence of this incident to the structure is provided.