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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.

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.

In the study of planetary drivetrains the substantially high transmitted loads lead to significant deflections in the supporting gear structures, which directly impact the gear pair alignment and alter the gear meshing. This contribution proposes an analytical formulation to model misaligned planetary gears by means of distributed gear contact forces. The presented model relies on a thin-sliced approach for the computation of misaligned contact forces, where the two main nonlinear phenomena affecting contact force accuracy are: (1) variable contact stiffness, and (2) contact detection and compression assessment. With regard to the former, this contribution proposes an internal gear extension of the analytical contact compliance approach previously developed by the authors for external gears. With regard to the latter, this contribution proposes a novel technique for analytical misaligned contact detection for three-dimensional helical gear contact. The model is validated with quasi-static simulations, including gear microgeometry modifications and misalignments, by comparison to numerical results. The computational efficiency of the presented method is enhanced by two kinds of contributions: a linearization of the compliance model to speed up the contact force computation, and an analytical contact Jacobian formulation. The availability of an efficient planetary gear contact model uncovers many interesting applications in the design and operational phases merged with digital twins frameworks.

Spiroid gears are used to transfer heavy loads with a significant reduction in input speed. Like most toothed gears, they are lubricated with oil whose physical properties change with temperature fluctuations, affecting the durability and reliability of the gear. Bearing this in mind, gear designers plan systems for measuring oil temperature during gear operation at the design stage. The authors of this paper are of the opinion that, in the case of spiroid gears, it may be insufficient to measure only oil temperature during gear operation. It seems that the working temperature of a pair of mating wheels has a decisive impact on the durability and reliability of the gear. The measurement of oil temperature in a tested gear should be treated as a supplementary measurement with the measurement of temperature on the toothed wheels as the basic measurement. Taking into consideration the above, an innovative test bench was designed and built, making it possible to observe how working parameters of the gear (torque and rotational speed) affect the temperature of the lubricating oil, but most of all, the working temperature of the pair of mating wheels. This paper presents, among others, the results of research on the impact of the rotational speed of the input shaft and load on the distribution of temperature on the toothed rim of the face gear.