Among the essential issues facing designers of strain wave gears, the provision for correct lubrication should be of paramount importance. The present paper presents the results of research on elasto-hydrodynamic oil film in meshing of a harmonic drive with an involute tooth profile. The research was carried out based on theoretical models developed by Dowson and Higginson. For the discussed structural problem, results of the study are presented graphically in the form of static characteristics of the oil film. Correct operation regimes were determined for two different oils. The paper also provides a review of information concerning the design and principle of operation of strain wave transmission.

The contact pattern between gear teeth is one of the most significant indicators of proper gear operation. This paper presents an analysis of the contact pattern of gears with a sinusoidal profile. The gear geometry was obtained through direct solid simulation of the machining process. Generally, analytical, numerical, and experimental methods are used for contact pattern analysis in gearboxes. This article presents contact pattern investigations using numerical methods and a novel experimental method that utilizes pressure measurement films. A proprietary program using image analysis was used for the contact pattern analysis. The numerical studies utilized the Finite Element Method (FEM) and the CAD method. The results obtained from the presented methods show good convergence.

Two types of hydrodynamically lubricated plain journal bearings were subject to examination differing in the method used to feed them with oil. The first type was fed from a lubrication pocket and the second from the bearing face side. Mathematical models were developed with two-way oil flow allowing to determine the oil film bearing capacity, the maximum pressure, the maximum temperature, and the film oil minimum height for given position of journal relative to solid bush. Static characteristics were developed used in the further course of the study to compare operating parameters of the considered types of bearings. Another issue considered in the paper is the effect of oil VG grade on bearing performance with conditions of oil feeding taken into account and results of the research presented.

Pressure measuring films make it possible to determine pressure in the contact zone. The solution is now successfully used in various scientific and industrial sectors, e.g., for research in medicine (orthopaedic template design), mechanical engineering or geology. Among the available types of pressure measuring system, mono-sheet or two-sheet films type can be found. This article focuses on the study of transfer sheets included in the set of two-sheet type films, within the framework of the described research work, qualitative and quantitative analyses of the transfer sheet microstructure were carried out with the aim of determining the changes in the microstructural properties of this sheet that occur as a result of force loading. There is a lack of description of the phenomena occurring during the use of pressure measurement films in the available literature. All research done to date was focused on practical use of this method in measurement of contact area or pressure distribution. The presented experimental results, together with a detailed description, will allow the reader to better understand the principle of operation and the mechanisms of phenomena that occur during pressure measurements using pressure measuring films. In addition, an analysis of the chemical composition of both sheets was carried out. The knowledge of the distribution of the microcapsules (size and number of pre-damaged ones) can be used in numerical simulation with the pressure measurement films. Also the manufacturers range of measurement accuracy (± 15%) was clarified by measuring the number of the pre-damaged microcapsules and non-uniform distribution of microcapsules.

This paper presents a comprehensive analysis of contact patterns in globoid worm gears with rectilinear axial tooth profiles. Two distinct methods are employed: a CAD-based simulation, and experimental techniques including two-sheet pressure measurement films. The CAD-based method for determining the contact pattern can be successfully applied to evaluate the form, size, and position of the contact pattern. Experimental results qualitatively confirm the theoretical predictions, although measured contact areas tend to be smaller due to incomplete filling and fabrication inaccuracies. The developed models offer reliable tools for evaluating tooth contact in worm gear design, potentially reducing prototyping costs. The proposed methods establish a solid foundation for further research and improvement of contact performance in double-enveloping worm gear systems.