A mathematical model of profile shifted quasi-involute arc-tooth-trace gears is obtained. The model includes functional relationships between the geometric-kinematic meshing characteristics and parameters of the generating surface as well as conditions which allow to prevent teeth undercutting and tip pointing. A short analysis of meshing characteristics value along the tooth trace is done for pressure angle value of 20º. This value of the angle was chosen as it is the most common one for general-duty gears, although the basic rack profile angle in the model is a variable quantity. The model can be used in the design and analysis of geometric-kinematic meshing characteristics of profile shifted quasi-involute arc-tooth-trace gears, cut by Gleason-type cutters with different profile angle value.

The submitted contribution deals with the wear of thin coatings applied to convex–concave gearings for gear made from C45E steel. The influence of the tribological characteristics (friction coefficient, wear, adhesion and hardness) of the TiN, TiCN coatings and the combined coating of TiCN + MoS₂ on convex–concave gearing is described, from the aspects of scuffing formation. Scuffing tests were done on C–C gears. Coatings were applied by arc–ion-plating (AIP) and magnetron sputter-ion-plating (MSIP) methods. The thickness of the deposited coating and its chemical composition were determined by SEM and EDX analysis. Load-bearing capacity was evaluated by a Niemann tester. The TiCN + MoS₂ combined coating with the MoS₂ layer on the top reached the lowest coefficient of friction. However, after a rapid wearing of the MoS₂ layer, this value dropped to a comparable value of TiCN. The nano-hardness of the TiCN layer was higher in comparison with TiN. Thin and soft MoS₂ layers cracked already at lower load levels and separated from the substrate at the 5th load stage. The formation of scuffings for selected coatings documented in this article was solved for convex–concave gearing working also in interaction with Biogear S 150 and Biohyd MS 46 oils.

The structure of the MAK M43 diesel high pressure fuel pump driving is analyzed. It is shown that presence of redundant constraints in its mechanism is the reason of roller bearings failure. It is proposed redundant constraints elimination by adding movabilities in mechanism.

This study aims to improve the technology for processing parts from hard-to-work materials, to study and substantiate the parameters of the plasma-assisted machining processing of surfaces of alloy steel parts to increase processing productivity and ensure the necessary quality of surface layers. Theoretical studies consist in determining the parameters of the thermal field of a workpiece during milling and turning with plasma heating. Experimental studies are based on a study of the interrelationship of the main indicators of machining with factors of preliminary plasma heating allowance.

Wear of nonstandard involute gears with two types of coatings, AlCrN and CrAlSiN, was studied. The coatings were applied by cathodic arc deposition. The gears were tested using a Niemann tester at a graduated load up to the 12th load stage and were compared to noncoated gears. Both Biogear S150 gear oil and PP90 universal hydraulic oil were applied during these tests. The thickness of deposited coatings and wear of gear teeth were studied by SEM and their chemical compositions were determined by EDS analysis. Maximal contact pressure of 1350 MPa was calculated in the region of the tooth flank at the 12th load stage. Maximal frictional stress was also calculated on the tooth flank. The resistance against wear of gears was evaluated based on the critical weight loss and mainly based on the critical surface roughness of gears. The critical roughness was exceeded at the 10th load stage for noncoated gears. For the gears with AlCrN and CrAlSiN coatings, the critical roughness was exceeded at the 11th load stage. Wear of AlCrN and CrAlSiN coatings was nonuniform along the height of tooth. Wear on the tooth flank was characterized by fragmentation of thin coatings and subsequent detaching of fragments from the steel substrate. The steel substrate was worn by microcutting, which caused the highest roughness on the tooth surface. On the tooth pitch, surface protrusions of coatings were smoothed, and coatings cracked and locally detached subsequently. On the tooth face, surface protrusions were also smoothed but coatings remained compact without crack initiations. Both experimental oils, Biogear S150 and PP90, proved to be suitable during Niemann tests as their temperatures did not exceed the limit value of 80 °C.

An analytical method for determination of a stress condition of butt welded thin-gauge plates with asymmetrical reinforcement is developed. The proposed method allows take into account the effect of the load application eccentricity on the tensile stress concentration factor (SCF) in the weld root zone. It is presented that the bending stresses, caused by this eccentricity, result in increasing the total stresses up to 75%. The results of analytical SCF calculations are in good agreement with the results obtained using the finite element method.