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Wolfrom-transmission are well known planetary transmission with low number of gears and used for very high transmission - ratio for example : i=100 or more. With the book of Mueller “Die Umlaufgetriebe” they are a type of reduced planetary transmission containing two simple transmission one a minus-type and one a plus-type for the two transmission inside. With a common carrier for both transmission and only one sun and two inner gears it is very compact but known for bad efficiency. Firms who produces such transmission are talking about a lot of problems, but no details are published so long. The Author will show that a calculation with low-loss-gears will improve the efficiency very much and that we can produce this type without a carrier. The forces which are active at the planet should be go direct to the housing and not about bearings in a carrier. Details and a modelling of such type will be presented in the conference.

Common methods of checking a gear that have been designed in reverse engineering are, for example, measurement with a modular caliper or disc micrometer. However, although these methods are among the most accurate, they allow only one or a few of the selected geometric parameters to be measured. The paper presents alternative methods of verification of the reconstructed outline of a very non-standard involute gear with the parameters m = 4.98, α = 26.325 °, x = 0.0695, y = 0.795, c* = 0.383. These methods are less accurate than the classic ones, but they allow for a comprehensive check of the entire outline of the reconstructed tooth. They are often used in industrial practice. However, here, in addition to the methodology, a short tolerance analysis was also carried out, which may to some extent compensate for the aforementioned measurement inaccuracy. The method consists in using the potential of a spreadsheet and CAD technique to generate an involute outline of a gear tooth whose geometry is recreated.

This paper presents a novel method for spur gear tooth profile optimization, addressing the challenge of designing gears with improved performance. Traditional gear designs often compromise between contact stress, wear, and noise. This research explores a wider design space to identify gear profiles offering a better balance. The proposed approach leverages tensor-based kinematics combined with the Reuleaux method for conjugate profile generation, creating a robust framework for exploring potential designs. This framework defines an objective function considering multiple performance criteria. Differential evolution is employed to search for novel tooth profiles minimizing this function. The performance of optimized profiles is compared against existing designs, including involute, S-gears, and cosine gears. Key performance indicators include Hertz contact and subsurface shear stresses, normal force, sliding factor, specific sliding, contact ratio, and gear mesh stiffness. Results demonstrate the method’s effectiveness in generating improved tooth profiles. Optimized solutions exhibited contact and shear stress reductions comparable to 30-degree involute and S-gears, suggesting improved pitting resistance and wear. Some designs showed substantial specific sliding reductions, indicating the potential for reduced heat generation and surface wear. While cosine gears showed reduced contact stress, they also exhibited lower contact ratios, potentially increasing dynamic loads. These optimized solutions offer a promising path towards designing high-performance gears tailored to specific applications. The method effectively explores the vast solution space and generates tooth profiles fulfilling desired optimization trade-offs, paving the way for future research incorporating additional performance criteria and exploring more complex gear geometries.

Unsustainable fishing is a major driver of change in marine ecosystems. The ways that fishing gears target fishes with different ecological functions are unclear, particularly in complex multispecies fisheries. Here, we examine whether artisanal fishing gears selectively target fishes with unique combinations of ecological traits (diet, body size, depth, position in water column, period of activity, schooling behaviour) in a coral reef ecosystem. We use coral reef fish landing data from 25 sites along the Kenyan coast collected over a 7‐year period. All fishing gears targeted a wide diversity of traits, but with some differentiation among gears. Fish assemblages captured by spearguns were significantly different from the other gear types, specializing on diurnal species that feed on sessile invertivores. Nets, including gillnets and beachseines, targeted the most functional diversity. Escape slot traps targeted the least functionally diverse assemblages. Basket traps and escape slot traps targeted the most functionally similar species of all two‐gear combinations. There were 163 functional entities (unique combinations of traits) captured in the fishery; however, 50% of the catch by each gear was from only two to six functional entities. Most of the differences in gear selectivity were due to unique and rarely targeted functional entities, that made up only a small proportion of the catch. Synthesis and applications. Coral reef fisheries target a breadth of functional entities (unique combinations of traits), but catches are heavily skewed towards relatively few functional entities. While banning specific gears will benefit rare functional entities in the catch, effort reductions will be necessary to alleviate pressure on commonly targeted functional entities. Coral reef fisheries target a breadth of functional entities (unique combinations of traits), but catches are heavily skewed towards relatively few functional entities. While banning specific gears will benefit rare functional entities in the catch, effort reductions will be necessary to alleviate pressure on commonly targeted functional entities.

Today's industrial practice shows that - in contrast to the past years, where gears were designed as standard as possible - machine parts are constructed on the basis of selecting non-standard parameters. This is because producers protect themselves against making additional parts from local suppliers for much less money by customers. The paper presents a geometric and strength analysis of an exemplary spur gear, which works as the second stage of a bevel-helical gear in the coiling mechanism of a multi-module machine producing bonell springs for mattresses. It was checked whether the transmission could be redesigned in such a way as to make its geometry as complicated as possible while maintaining the appropriate strength properties. Finally, there are graphs that can be helpful in this type of reconstruction process, and the subsequent stages of this work can be treated as a kind of algorithm for the discussed conversion of geometric parameters of the gear.

Tooth spall is a prevalent gear fault that reduces mesh stiffness and adversely affects transmission ability of gear systems. While plenty of research focuses on tooth spall faults in spur and helical gears, few analytical approaches were established to calculate the time-varying mesh stiffness in straight bevel gears, especially those affected by tooth spall. This deficiency can be attributed to the lack of an accurate tooth spall model. This paper proposes an approach for straight bevel gears mesh stiffness calculation with a curved-bottom spall. The spur gear spall model is modified to adapt to the tooth profile in straight bevel gears. The time-varying mesh stiffness calculation formulas are then revised in spall region. Using potential energy, Hertzian contact stiffness is calculated considering load distribution between gear teeth. The foundation stiffness calculation is updated considering practical gear shape. Tooth stiffness caused by axial forces is also considered. Finite element analysis is utilized for the theoretical method verification, which suggests a high consistency of results between two methods. The low error between the proposed approach and finite element approach implies that the proposed method is acceptable for practical use.

Planetary gears consisting of simple external gear wheels and an internal ring gear are widely used in industry in various fields. This type of drive is most commonly found in robots, and it is also frequently used in the automotive industry, such as in wheel hub drives, in addition to general engineering. This study investigates the design of simple planetary gears manufactured with involute gearing. In simple internal gear planetary gears, the orbiting motion of the planetary gear is transferred to the output shaft by a radial balancing clutch and converted into rotary motion through the planetary gear’s guiding holes and the output element’s pins. The guiding holes reduce the planetary gear teeth strength, and the rim thickness “h” has a fundamental influence on the resulting tooth root stress. The main objective of this research is to design external gears with relief for simple planetary gears with a rim thickness “h” that does not decrease the load-carrying capacity. The dimensioning of involute gearing is well known, but the tooth root weakening effect of the clearance holes in such planetary gears is not known. Therefore, this paper focuses on analyzing how the size and position of the guiding holes influence tooth root stress, using finite element method (FEM) calculations performed in SolidWorks 2023. This study aimed to determine the rim thickness “h” required for the design of such a gear in order not to weaken the load-carrying capacity of the gear teeth. As a result of the research, the design of the guiding holes and the wheel relief holes can be performed with an accurate knowledge of their influence on tooth stress. The research results also make it possible to design this type of planetary gear using simple analytical calculation algorithms. Our goal was to define a simple design limit that could be used specifically in the preliminary design phase. This allows designers to determine the positions and dimensions of the guiding holes in the preliminary design phase without affecting the tooth stress.

Dynamic models are important for developing gear diagnostics methods since they allow physical phenomena occurring during operation to be studied in a relatively simple environment. The main challenge in gear modeling is the calculation of the time-variant gear mesh stiffness, and this challenge is even greater in helical gears. The mechanism of helical gears is more complex than in spur gears; the helix angle both adds an axial component to the contact force and also makes the contact line three-dimensional. This study suggests a novel dynamic model for helical gear vibrations that combines an existing validated dynamic model for spur gears with a unique extension for helical gears. The extension is based on a common method called “multi-slice”, according to which the helical tooth width is divided into infinitesimal slices, and each slice is treated as spur tooth. The suggested model introduces a novel implementation of the multi-slice method that overcomes the aforementioned challenges with only few parameters and calculations, depends on the tooth geometry. Furthermore, for the first time in helical gear modeling, the manufacturing profile errors are integrated to the model to generate scatter in the data that can better reflect the reality. The model is validated experimentally and for two different test-rigs by a qualitative comparison of the RMS of the vibration signal. The simulations and the measured data show similar behavior at different ranges of rotational speed and applied load, emphasizing the potential inherent in the model for future work on gear fault diagnosis.

The nonlinear dynamic model of the NW (planetary gear structure with internal and external meshing and without planet carrier) planetary gear bearing was established in this study, taking into account factors such as random wind speed, time-varying support stiffness, bearing clearance, transmission error, tooth backlash, flexible ring gear, time-varying meshing stiffness, and tooth surface friction. The system's nonlinear behavior was described using phase trajectory plane, time–frequency analysis, time history, 3D frequency spectrum, FFT spectrum, phase diagram, and Poincaré map, as well as bifurcation diagram. Additionally, the superharmonic resonance characteristics of the system were analyzed using a multi-scale method, and the stability conditions for superharmonic resonance were determined through numerical analysis. Furthermore, the effects of meshing damping, displacement control parameters, and speed control parameters on the amplitude–frequency characteristics of the NW planetary gear-bearing system were examined. The conclusions indicate that the NW planetary gear-bearing system exhibits various nonlinear characteristics, and the system's stability can be improved by increasing damping and selecting appropriate time delay parameters.

Closed differential gear transmission systems are widely used in applications such as wind turbines and aviation equipment, yet the highly complex 3D nonlinear dynamics of these systems, particularly with floating herringbone gears, have not been adequately explored. Nevertheless, there is an urgent need for a specialized analytical model for the 3D floating of herringbone gears in space, which is crucial for studying the nonlinear dynamic behavior of gear systems. This article introduces a novel 3D floating analysis method that accounts for dynamic meshing parameters, coupled dynamic backlash with multiple clearances, and Time-Varying Meshing Stiffness (TVMS) of floating gears. Building on this approach, the study develops a 134-degree-of-freedom Bending Torsion Axial Pendular (BTAP) nonlinear dynamic model for the Coaxial Reverse Closed Differential Herringbone Gear Transmission System (CRCDHGTS). The model investigates the system’s bifurcation characteristics and vibration behavior under varying radial, axial, and pendular floating conditions and is validated through bench vibration experiments. This model significantly enhances the accuracy of predicting the nonlinear dynamics of multi-degree-of-freedom systems operating under multiple clearance couplings, outperforming traditional models. The findings indicate that maintaining the radial floating value of gears within 0-20 μm ensures relatively stable dynamic behavior, avoiding multi-periodic and chaotic motion. Axial floating introduces diverse bifurcation characteristics, with values exceeding 0.28 μm leading to instability. Additionally, a gear end-face deviation angle around the X and Y axes greater than 0.007° results in complex bifurcation patterns and an increased risk of chaotic motion. This work establishes a theoretical foundation for 3D floating nonlinear vibration analysis in planetary gear transmission systems.