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Letteratura scientifica selezionata sul tema "Gear transmissions"

Autore: Grafiati

Pubblicato: 16 novembre 2024

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Articoli di riviste sul tema "Gear transmissions"

Litvin, F. L., J. C. Wang, R. B. Bossler, Y. J. D. Chen, G. Heath e D. G. Lewicki. "Application of Face-Gear Drives in Helicopter Transmissions". Journal of Mechanical Design 116, n. 3 (1 settembre 1994): 672–76. http://dx.doi.org/10.1115/1.2919434.

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The use of face-gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face-gears was described. Face-gear design is discussed. Topics included basic design geometry, tooth generation, limiting inner and outer radii, and recommendation for the gear ratio. Face-gear experimental studies were also included and the feasibility of face-gears in high-speed, high-load applications such as helicopter transmissions was demonstrated. Torque-split tests were performed and demonstrated an accurate split of torque using the face-gear concept.

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Amir Mustafayev, Amir Mustafayev, e Chingiz Nasirov Chingiz Nasirov. "MATHEMATICAL EXPRESSIONS FOR TEMPERATURE IN THE CONTACT ZONE OF TEETH OF THE GEAR MECHANISMS". ETM - Equipment, Technologies, Materials 14, n. 02 (18 aprile 2023): 126–34. http://dx.doi.org/10.36962/etm14022023-126.

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Transmission gears are very widely used in modern machine building. Despite that electrical transmissions used in machine building industry, mainly mechanical transmissions are widely used in the industry. Because mechanical transmissions are independent and better than other transmisions. Distributing power between the transmission mechanisms and working units of various machines, changing the angle of momentum, by adjusting the speed of the parts, it is possible to change the type of movement, turn on and off the mechanism, change the direction of the transmission mechanisms. One of the most widespread types of transmission technology is the gear transmission. Tens of thousands of kilowatt-hours of gears can be transmitted. Advantages of gear transmission in comparison with others is their ability to maintain their reliability and long term functioning of the teeth, big value of the working coefficient (0,9 ÷ 0,99), simple construction, lack of special service, simplicity of the transmission number and compactness of dimensions. The missing aspects of these transmissions are high precision in their preparation and installation, and low noise level. The main criterion for the working ability of the closed gear transmissions is the contact endurance of the active surface of the tooth. For this reason, the main dimensions of the transmission are determined by the contact tension and by teeth bending. Keywords: gear wheel, tension, endurance, bending

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Salamandra, Konstantin. "Static analysis and parameters synthesis of planetary-layshaft transmissions with three power flows". MATEC Web of Conferences 224 (2018): 02040. http://dx.doi.org/10.1051/matecconf/201822402040.

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The increase in the number of transmission ratios in the vehicles gearboxes leads to an increase in the number of mechanisms used and their complication. One way to obtain simple designs of multi-speed transmissions with smaller number of gears, clutches, brakes and synchronizers is to use combinations of planetary differential gears and gears with fixed axes (planetary-layshaft transmissions). The article presents a static analysis of a planetary-layshaft transmissions with three parallel power flows for obtaining the dependencies between the gear ratios of the internal mechanisms and the speed ratios of the transmission. A technique for determination the gear ratios of the internal mechanisms for providing a close to a given series of transmission ratios is described.

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Mustafayev, Amir G., e Chingiz R. Nasirov. "A study of factors affecting wear and destruction of teeth in gear mechanisms". Nafta-Gaz 79, n. 9 (settembre 2023): 604–10. http://dx.doi.org/10.18668/ng.2023.09.06.

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Transmission gears are very widely used in the modern construction of the machine. Even though electrical transmissions are used, mainly mechanical transmissions are widely used in the machine building industry as they are independent and better than other transmissions. Distributing power between the transmission mechanisms and working units of various machines, by changing the angle of momentum by adjusting the speed of the parts, it is possible to change the type of movement, turn the mechanism on and off, and change the direction of the transmission mechanisms. One of the most widespread types of transmission technology is gear transmission. Tens of thousands of kilowatt-hours of gears can be transmitted. The advantages of gear transmission in comparison with others are their ability to maintain their reliability and long-term functioning of the teeth, high value of the working coefficient (0.90–0.99), simple construction, lack of special service, simplicity of the transmission number and compactness of dimensions. The missing aspects of these transmissions are high precision in their preparation and installation, and low noise level. The main criterion for the working ability of the closed gear transmissions is the contact endurance of the active surface of the tooth. For this reason, the main dimensions of the transmission are determined by the contact tension and by teeth bending.

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Radzevich, Stephen P. "A Way to Improve the Accuracy of Hobbed Involute Gears". Journal of Mechanical Design 129, n. 10 (19 ottobre 2006): 1076–85. http://dx.doi.org/10.1115/1.2761919.

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Involute gears are widely used in the design of machines and mechanisms. Performance of gear transmissions, e.g., performance of automobile transmissions, strongly depends upon the accuracy of gears of which the transmission is comprised. The higher the gear accuracy, the higher performance of the gear transmission observed. An increase of accuracy of involute gears reduces vibration of the transmission, and causes lower noise excitation. A significant amount of gears for the needs of the automotive industry is manufactured by hobbing. Reported in this paper is a way to improve the accuracy of hobbed involute gears that requires an appropriate alteration of design parameters of the hob to be applied. The required correction of design parameters of the hob can be computed on the premises of in-depth analysis of kinematic geometry of meshing of the hob and of the work gear, i.e., of design parameters of the hob, as well as an analysis of kinematics of meshing of the gear work and of the hob. An analytical approach for computation of the required alterations in design parameters of the involute hob is reported in the paper. Using commercial software MathCAD/Scientific, numerous computer codes are developed for performing the necessary computations. A numerical example of computation is presented. The reported results of research are ready to put into production.

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Maláková, Silvia, Matej Urbanský, Gabriel Fedorko, Vieroslav Molnár e Samuel Sivak. "Design of Geometrical Parameters and Kinematical Characteristics of a Non-circular Gear Transmission for Given Parameters". Applied Sciences 11, n. 3 (22 gennaio 2021): 1000. http://dx.doi.org/10.3390/app11031000.

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In this paper, the authors present the design of a suitable gear transmission with the continuously changing gear ratio in the range from 0.5 through 1.0 to 2.0 and back during one revolution of intermeshing gears, according to demands specified for a practical application. The gear train was designed as a pair of identical elliptical gears and the design procedure of the suitable pitch curve (ellipse) is described. The center of rotation of each of the gears is coincident with one of the pitch ellipse foci, so the gears are placed eccentrically. The gear teeth have involute profiles, but the involutes for the active and for the passive tooth sides are different. These are gears with an asymmetrical tooth profile. In the final part, the paper deals with kinematical characteristics of the designed non-circular gear transmission, which differ from the kinematical characteristics of standard circular gear transmissions with a constant gear ratio.

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Brancati, Renato, Stefano Pagano e Ernesto Rocca. "Dynamic Behaviour of an Automotive Dual Clutch Transmission during Gear Shift Maneuvers". Applied Sciences 13, n. 8 (12 aprile 2023): 4828. http://dx.doi.org/10.3390/app13084828.

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The paper presents a model for the torsional dynamics of an automotive driveline equipped with a Dual Clutch Transmission (DCT), focusing on the gear rattle phenomenon arising during the transients of engagement and disengagement of the clutches, and during the synchronizing manoeuvres. This vibro-acoustic phenomenon, particularly annoying in automotive transmissions, can be accentuated by the presence of many unloaded gears in this type of gearbox. Dual Clutch Transmission systems are today largely diffused in the car automatic transmissions, permitting fast gear shifts and avoiding the interruption of the drive torque. The study is conducted by adopting a tribo-dynamic model with lumped parameters, considering the oil lubricant between the teeth of the unloaded gears acting as a damper during the impacts. A layout of a gearbox with six speed ratios has been assumed, in which a dual clutch system transmits the drive torque alternatively between the various gear pairs in the odd and even branches. The results of the numerical simulations show that this kind of transmission system is characterised by hard rattling behaviour, particularly during the rapid phases of clutches engaging/disengaging and during the gears synchronisation. Some solutions to attenuate the torsional vibrations, and therefore the rattling behaviour of the unloaded gears in a DCT gearbox, can be analysed by the proposed model to determine, as example, the time duration of the gear shift phase or of the pre-selection phase to the next gear, as well as to identify the optimal lubrication conditions of the gear pairs during the gear shift transients.

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Wu, Yi-Chang, e Che-Wei Chang. "DEVELOPMENT OF 3-SPEED REAR HUB BICYCLE TRANSMISSIONS WITH GEAR-SHIFTING MECHANISMS". Transactions of the Canadian Society for Mechanical Engineering 39, n. 3 (settembre 2015): 407–18. http://dx.doi.org/10.1139/tcsme-2015-0030.

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Rear hub bicycle transmissions require less maintenance and are more reliable than rear derailleurs. This study proposes a systematic design process for the conceptual design of 3-speed rear hub bicycle transmissions. By analyzing the kinematics of a basic epicyclic gear mechanism using the fundamental circuit method, the gear sequence and clutching sequence arrangements for 3-speed rear hub transmissions can be obtained. The numbers of gear-teeth for all gear elements resulting in a minimum installation space and satisfying the required speed ratio at each gear stage are determined. A gear-shifting mechanism is constructed to sequentially control the power-flow path within the epicyclic gear mechanism so as to provide three forward gears. An atlas of 3-speed rear hub bicycle transmissions is listed, where three devices are new design concepts and are suitable for further embodiment design. The results of this study will lead to the creation of new multi-speed rear hub bicycle transmissions.

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Handschuh, R. F., D. G. Lewicki e R. B. Bossler. "Experimental Testing of Prototype Face Gears for Helicopter Transmissions". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 208, n. 2 (luglio 1994): 129–36. http://dx.doi.org/10.1243/pime_proc_1994_208_262_02.

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An experimental programme to test the feasibility of using face gears in a high-speed and high-power environment was conducted. Four face gear sets were tested, two sets at a time, in a closed-loop test stand at pinion rotational speeds to 19 100 r/min and to 271 kW (364 b.h.p.). The test gear sets were one-half scale of the helicopter design gear set. Testing the gears at one-eighth power, the test gear set had slightly increased bending and compressive stresses when compared to the full-scale design. The tests were performed in the NASA Lewis spiral bevel gear test facility. All four sets of gears successfully ran at 100 per cent of design torque and speed for 30 million pinion cycles, and two sets successfully ran at 200 per cent of torque for an additional 30 million pinion cycles. The results, although limited, demonstrated the feasibility of using face gears for high-speed, high-load applications.

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Liu, Dezheng, Yan Li, Zhongren Wang, You Wang e Yu Wang. "Modeling and Analysis of Effective Case Depth on Meshing Strength of Internal Gear Transmissions". Mathematical Problems in Engineering 2018 (30 dicembre 2018): 1–12. http://dx.doi.org/10.1155/2018/5153292.

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The effective case depth (ECD) plays an important role in the meshing strength of internal gear transmissions. Carburizing quenching heat treatment is commonly used to enhance gear strength and wear resistance. However, the different ECDs in internal and external gears caused by heat treatment significantly affect the meshing strength, causing vibration, reducing gear service life, and hastening malfunction in internal gear transmission. In this study, we conducted an investigation of different ECDs by the heat treatment of carburized gear pairs by numerical simulation with the finite element method (FEM) and experiment tests. We analyzed three different carburized layer models, with the ECD in the internal gear being greater than, less than, and equal to the ECD in the external gear. In addition, we investigated the ability to distinguish between hardness gradients in gear teeth by dividing the carburized depth into seven layers to improve modeling accuracy. Results revealed that the meshing strength of internal gear transmission could be significantly enhanced by adopting the model with the ECD in the internal gear being less than the ECD in the external gear, and moreover, the shear stress of carburized gears initially increased and then decreased along with depth direction, and the maximum value appeared in the middle of the lower surface.

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Più fonti

Tesi sul tema "Gear transmissions"

Sainte-Marie, Nina. "A transmission-error-based gear dynamic model : Applications to single- and multi-mesh transmissions". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI133/document.

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Les spectres de bruit mesurés en cabine d’hélicoptère montrent que la boîte de transmission principale (BTP) est un des principaux contributeurs au bruit perçu par les usagers. Elle génère en effet plusieurs raies émergeant fortement du bruit large bande et dont les fréquences se situent dans la plage de sensibilité maximale de l’oreille humaine. Dans un contexte d’amélioration permanente du confort acoustique des usagers, un modèle numérique est développé pour prédire le comportement dynamique des BTP. Les équations du mouvement sont écrites sur la base de fonctions du temps représentatives des excitations générées par l’engrènement (raideur d’engrènement et erreurs de transmission). Plusieurs éléments de validation sont présentés pour confirmer la pertinence de la formulation proposée. Différents résultats numériques et expérimentaux de la littérature sont utilisés à des fins de comparaison, montrant que le modèle s’applique aux systèmes à simple étage de réduction, par engrenage cylindrique ou spiro-conique. La validation est ensuite étendue aux systèmes à deux étages de réduction et les résultats confirment que la formulation basée sur les erreurs de transmission permet de tenir compte des corrections de profil. Finalement, le modèle est utilisé pour diverses applications. Premièrement, l’influence des erreurs de pas sur le comportement dynamique de transmissions par engrenages est discutée, ainsi que l’influence combinée du niveau de chargement appliqué. Dans un second temps, la relation entre l’erreur de transmission dynamique et différents coefficients dynamiques est étudiée. Le contenu spectral de la réponse au niveau des roulements est ensuite analysé pour des systèmes à deux engrènements cylindriques et l’influence de différents paramètres est discutée. Enfin, une application est réalisée sur un système comprenant un engrenage cylindrique et un engrenage spiro-conique. Les phénomènes de couplage entre les étages successifs sont mis en évidence ainsi que la contribution des deux engrènements au contenu spectral de la réponse aux roulements
Noise measurements have shown that helicopters main gearboxes highly contribute to the overall cabin noise. Gear mesh vibrations propagate through the shafts to the rolling element bearings and the casing which becomes a source of radiated noise. The latter is characterized by high-amplitude tones emerging from broadband noise whose frequencies lie in the range of maximum human ear sensitivity. In the context of continuous improvement in the acoustic comfort of helicopter passengers, it is therefore necessary to analyse and optimize gearbox vibrations in order to reduce casing noise radiations. The research work presented in this memoir is focused on the development of a numerical model dedicated to the prediction of gear system dynamic behaviour, comprising several gear stages and different types of gears. This model relies on classic beam and lumped parameter elements along with specific two-node gear elements for both cylindrical (spur, helical) and spiral-bevel gears. The equations of motion are developed based on time-varying functions representative of mesh excitations which comprise: (a) mesh stiffness functions, (b) quasi-static transmission error under load, and (c) kinematic (or no-load) transmission error. A number of comparisons with benchmark numerical and experimental results from the literature are presented which demonstrate that the proposed approach is sound as far as single-stage systems with spur, helical or spiral-bevel gears are considered. Validations are then extended to double-stage gears and, here again, it is confirmed that the proposed transmission error based formulation is accurate and can account for tooth shape modifications. In the second part of the memoir, several examples of application are presented and commented upon. First, the combined influence of tooth pitch errors and load on the dynamic behaviour of gear transmissions is tackled. An extended three-dimensional model and a reduced torsional version are then confronted in order to investigate the dependency between dynamic transmission errors and mesh force / root stress dynamic factors. Further investigations on bearing dynamic response in two-stage spur gear systems are conducted and the particular contributions of profile modifications are analysed. Finally, a system combining a cylindrical gear and a spiral-bevel gear is considered and particular attention is paid to the dynamic couplings between the various meshes and their influence on bearing dynamic responses

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Janakiraman, Venkatakrishna. "Modelling of Steady-State and Transient Power Losses in Planetary Gear Trains". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492510708602145.

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Kurth, Franz [Verfasser]. "Efficiency Determination and Synthesis of Complex-Compound Planetary Gear Transmissions / Franz Kurth". München : Verlag Dr. Hut, 2012. http://d-nb.info/1029400172/34.

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Brauer, Jesper. "Investigation of transmisison error, friction and wear in anti-backlash involute gear transmissions". Doctoral thesis, KTH, Machine Design, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3590.

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Brethee, Khaldoon F. "Condition monitoring of helical gear transmissions based on vibration modelling and signal processing". Thesis, University of Huddersfield, 2018. http://eprints.hud.ac.uk/id/eprint/34519/.

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Condition monitoring (CM) of gear transmission has attracted extensive research in recent years. In particular, the detection and diagnosis of its faults in their early stages to minimise cost by maximising time available for planned maintenance and giving greater opportunity for avoiding a system breakdown. However, the diagnostic results obtained from monitored signals are often unsatisfactory because mainstream technologies using vibration response do not sufficiently account for the effect of friction and lubrication. To develop a more advanced and accurate diagnosis, this research has focused on investigating the nonlinearities of vibration generation and transmission with the viscoelastic properties of lubrication, to provide an in-depth understanding of vibration generating mechanisms and hence develop more effective signal processing methods for early detection and accurate diagnosis of gear incipient faults. A comprehensive dynamic model has been developed to study the dynamic responses of a multistage helical gear transmission system. It includes not only time-varying stiffness but also tooth friction forces based on an elastohydrodynamic lubrication (EHL) model. In addition, the progression of a light wear process is modelled by reducing stiffness function profile, in which the 2nd and 3rd harmonics of the meshing frequency (and their sidebands) show significant alteration that support fault diagnostic at early stages. Numerical and experimental results show that the friction and progressive wear induced vibration excitations will change slightly the amplitudes of the spectral peaks at both the mesh frequency and its sideband components at different orders, which provides theoretical supports for extracting reliable diagnostic signatures. As such changes in vibrations are extremely small and submerged in noise, it is clear that effective techniques for enhancing the signal-to-noise ratio, such as time synchronous averaging (TSA) and modulation signal bispectrum (MSB) are required to reveal such changes. MSB is preferred as it allows small amplitude sidebands to be accurately characterised in a nonlinear way without information loss and does not impose any addition demands regarding angular displacement measurement as does TSA. With the successful diagnosis of slight wear in helical gears, the research progressed to validate the capability of MSB based methods to diagnose four common gear faults relating to gear tribological conditions; lubrication shortfall, changes in lubrication viscosity, water in oil, and increased bearing clearances. The results show that MSB signatures allows accurate differentiation between these small changes, confirming the model and signal processing proposed in this thesis.

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Fargere, Romain. "Simulation du comportement dynamique des transmissions par engrenages sur paliers hydrodynamiques". Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0130/document.

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Ce travail vise à prédire le comportement dynamique de transmissions par engrenages supportées par des paliers hydrodynamiques, semblables à celles utilisées dans le domaine de la propulsion navale. Un modèle couplé de transmission mécanique est présenté ; il traite la plupart des interactions possibles entre les engrenages, les arbres et les paliers. Un élément d’engrenages à dentures larges, avec raideur non linéaire et dépendante du temps, est combiné à des éléments finis de poutre alors que la contribution des paliers est introduite par la résolution directe de l’équation de REYNOLDS et d’un model thermique simplifié. A cause des jeux de fonctionnement des paliers, une attention particulière a été portée à la définition de l’état de référence et des degrés de liberté. La réponse du système est calculée par la combinaison d’un schéma d’intégration temporelle, d’une méthode de NEWTON-RAPHSON et d’un algorithme de contact normal unilatéral de manière à ce que les conditions de contact aux paliers et entre les dents soient simultanément traitées. Les résultats de simulation sont comparés à des mesures réalisées sur un banc d’essai de haute précision possédant un train simple étage en dentures droites et hélicoïdales, supporté par des paliers lisses de type hydrodynamique. Les comparaisons fournissent un bon accord et aboutissent à la validation du modèle de couplage tant sur les aspects globaux que locaux. Bon nombre de résultats sont également présentés, qui montrent que certains paramètres, bien souvent ignorés dans les modèles de la littérature, tels que la position de la zone d’alimentation des paliers, la température de lubrifiant dans les paliers, les accouplements avec l’environnement extérieur peuvent fortement modifier l’équilibre statique et le comportement dynamique du système, jusqu’aux contacts entre les dents
The present work is aimed at predicting the dynamic behaviour of geared transmissions supported by hydrodynamic journal bearings, similar to those used in naval propulsion. A global model of mechanical transmissions is introduced which deals with most of the possible interactions between gears, shafts and hydrodynamic journal bearings. A specific element for wide-faced gears with non linear time-varying mesh stiffness and tooth shape deviations is combined with shaft finite elements whereas the bearing contributions are introduced based on the direct solution of REYNOLDS’ equation and a simple thermal model. Because of the large bearing clearances, particular attention has been paid to the definition of the degrees-of-freedom and their datum. Solutions are derived by combining a time-step integration scheme, a NEWTON-RAPHSON method and a normal contact algorithm in such a way that the contact conditions in the bearings and on the gear teeth are simultaneously dealt with. The simulation results are compared with the measurement obtained on a high-precision test rig with single stage spur and helical gears supported by hydrodynamic journal bearings. The experimental and simulation results compare well thus validating the simulation strategy both at the global and local scales. A number of results are presented which show that parameters often discarded in global models such as the location of the oil inlet area, the oil temperature in the bearings and external couplings with mechanical parts can be influential on the static and dynamic behaviour of the system

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White, Robert J. "Exploration of a Strategy for Reducing Gear Noise in Planetary Transmissions and Evaluation of Laser Vibrometry as a Means for Measuring Transmission Error". Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1129928063.

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Larsson, Camilla. "Reduction of oil pump losses in automatic transmissions". Thesis, Linköpings universitet, Fordonssystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111937.

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In the vehicle industry it is of great interest to reduce the emissions and lower the fuel consumption.Up to now a lot of effort has been put into increasing the efficiency of the engine,but it starts to get expensive to keep improving the engine. In this master thesis the transmissionand especially the oil supply to the transmission is investigated. An example of how the requirements of an oil pump can be decided is described. Knowingthe requirements different pumps may be adapted to meet the demands. The gear pumpused today is compared with a variable displacement pump and an electric pump. The gearpump is not possible to control, but the other two are. A few simple control strategies areintroduced. The strategies are implemented and the three pumps are used in the same drivecycle. It is shown that it is possible to reduce the energy that the pump requires if it isreplaced by a variable vane pump or an electric pump.

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Vinayak, Harsh. "Multi-body Dynamics and Modal Analysis Approaches for Multi-mesh Transmissions with Compliant Gear Bodies". The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392059093.

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Terrin, Andrea. "Analysis and design against pitting of gears in power transmissions for off-highway vehicles". Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3426672.

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The work described in this thesis has been developed within the scope of a higher education apprenticeship program in cooperation with Carraro S.p.A., global player in the market of power drivelines for vehicles employed in industrial and agricultural applications, also addressed as off-highway vehicles. The study is aimed to the analysis of the mechanisms leading to contact fatigue failures of gears and to the development of reliable and efficient methods to characterize gears materials. Pitting is the most hazardous among rolling contact fatigue phenomena occurring in gears. It manifests with the formation of craters on the surfaces leading to noise, vibration and loss of efficiency, and eventually may constitute the initiation cause for secondary damages such as tooth fractures. The sun gears of the planetary gear sets, which constitute the final stage of reduction in off-highway drivelines, are particularly susceptible to pitting failures, being subjected to high torques under poor lubricating conditions determined by the low speed of rotation. In this work, contact fatigue phenomena are studied by the observation of their occurrence in sun gears failed during endurance tests performed on the whole axles. The failure mechanisms as well as the most common approaches proposed in the literature for the evaluation of the load carrying capacity and the prevision of the lifetime of gears are commented through an analysis of the existing literature on the subject. Then the problem of the design against pitting of case hardened gears is faced from two different perspectives: on the one hand the determination of reliable endurance limits for the materials used by the suppliers of Carraro S.p.A. in the manufacturing of case hardened gears, based on a reanalysis of the database of validation tests performed in the past on the whole axles; on the other hand an experimental analysis of the pressure distribution on gear teeth during operation is reported. This latter study was useful to assess the major discrepancies between theoretical models and actual systems, in order to improve the awareness in the use of calculation software packages dedicated to the prevision of the lifetimes of gears. Finally, the development of a test rig for the contact fatigue characterization of gears materials by means of relatively fast tests on simple disc specimens is described. The first attempts to resemble the operating conditions of a particular gear pair with a dedicated design of specimens and to correlate the fatigue performances of gears and discs are discussed as well.
Il lavoro descritto in questa tesi è stato sviluppato nell'ambito di un programma di apprendistato in alta formazione e ricerca in collaborazione con Carraro S.p.A., azienda leader nel mercato delle trasmissioni di potenza per veicoli “off-highway”, ovvero veicoli destinati ad uso in campo agricolo ed industriale. Lo studio è finalizzato all'analisi dei meccanismi che portano al cedimento per fatica da contatto degli ingranaggi, ed allo sviluppo di metodi affidabili ed efficienti per caratterizzare i materiali con cui vengono realizzate le ruote dentate. Il pitting è il più pericoloso tra i fenomeni di fatica da contatto a cui gli ingranaggi sono soggetti. Si manifesta con la formazione di crateri sulle superfici, che causano rumore, vibrazioni e perdita di efficienza, e può a sua volta dare luogo a danni secondari come la frattura dei denti. Le ruote solari dei riduttori epicicloidali che costituiscono lo stadio finale di riduzione delle trasmissioni fuoristrada sono particolarmente critiche dal punto di vista del pitting, essendo soggette a coppie elevate ed a condizioni di scarsa lubrificazione determinate dalla bassa velocità di rotazione. In questo lavoro, i fenomeni di fatica da contatto sono studiati sulla base della loro osservazione su ruote solari danneggiate durante i test di validazione eseguiti sugli assali completi. I meccanismi di cedimento, così come gli approcci più comuni proposti in letteratura per la valutazione della capacità di carico e la previsione della durata degli ingranaggi, sono commentati attraverso un'analisi della letteratura esistente sull'argomento. Il problema della progettazione a pitting degli ingranaggi cementati è quindi affrontato da due diversi punti di vista: in primo luogo i limiti di resistenza per i materiali utilizzati dai fornitori di Carraro S.p.A. nella produzione di ingranaggi cementati sono stati determinati sulla base di una rianalisi del database dei test di validazione eseguiti in passato gli assali completi; in secondo luogo, un'analisi sperimentale della distribuzione della pressione sui denti delle ruote solari durante il funzionamento ha permesso di valutare le principali discrepanze tra i modelli teorici e i sistemi attuali, al fine di migliorare la consapevolezza nell'uso dei pacchetti software di calcolo dedicati alla previsione della durata delle ruote dentate. Infine, viene descritto lo sviluppo di un banco di prova per la caratterizzazione della fatica da contatto di materiali per ruote dentate, mediante prove relativamente veloci su coppie di dischi di semplice ed economica realizzazione. Viene inoltre presentato l’approccio utilizzato per ricreare le condizioni operative di una particolare coppia di ruote dentate mediante un design dedicato di provini, e sono discusse le problematiche riscontrate nel tentativo di ricavare una correlazione fra le prestazioni a fatica di ingranaggi e dischi.

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Libri sul tema "Gear transmissions"

Choy, Fred K. Dynamics analysis of multimesh-gear helicopter transmissions. Cleveland, Ohio: Lewis Research Center, 1988.

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P, Townsend Dennis, Oswald Fred B e United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., a cura di. Dynamic analysis of multimesh-gear helicopter transmissions. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988.

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L, Litvin F., United States. Army Aviation Systems Command. e United States. National Aeronautics and Space Administration., a cura di. Application of face-gear drives in helicopter transmissions. [Washington, DC: National Aeronautics and Space Administration, 1992.

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Handschuh, Robert F. Experimental and analytical assessment of the thermal behavior of spiral bevel gears. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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Handschuh, Robert F. Experimental and analytical assessment of the thermal behavior of spiral bevel gears. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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Handschuh, Robert F. Experimental and analytical assessment of the thermal behavior of spiral bevel gears. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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United States. National Aeronautics and Space Administration., a cura di. Gear and transmission research at NASA Lewis Research Center. [Washington, DC]: National Aeronautics and Space Administration, 1997.

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K, Choy Fred, e Lewis Research Center, a cura di. Effects of gear box vibration and mass imbalance on the dynamics of multi-stage gear transmissions. [Cleveland, Ohio: Lewis Research Center, 1991.

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Capitoli di libri sul tema "Gear transmissions"

Ognjanović, Milosav, e Miloš Ristić. "Gear System Reliability-Based Design of Gear Drive Units". In Power Transmissions, 155–64. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_10.

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Ognjanović, Milosav, Miloš Ristić e Sanja Vasin. "Bearings Failure of Gear Drive Unit Caused by Gear Resonance". In Power Transmissions, 389–98. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_30.

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Ivanov, Konstantin, Almas Dinassylov e Ekaterina Yaroslavceva. "Gear Variator—Scientific Reality". In Mechanisms, Transmissions and Applications, 169–76. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17067-1_18.

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Spitas, Vasilios, e Christos Spitas. "Design of Loboid Gear Pairs Using Involute Discretization". In Power Transmissions, 417–25. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_32.

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Vasie, Marius, Domenico Mundo e Laurenţia Andrei. "New Algorithm for Variable Speed Gear Generation Process". In Power Transmissions, 435–44. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_34.

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Kurokawa, Syuhei, Yoji Umezaki, Morihisa Hoga, Ryohei Ishimaru, Osamu Ohnishi e Toshiro Doi. "Application of MEMS Technique for Micro Gear Metrology". In Power Transmissions, 457–66. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_36.

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Bostan, Ion, e Valeriu Dulgheru. "Development of Planetary Precessional Transmission with Multicouple Gear". In Power Transmissions, 597–607. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_48.

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Darbinyan, Hrayr. "Task Based Conceptual Design Method for Gear Chamfering Mechanisms". In Power Transmissions, 279–88. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_20.

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Kapelevich, A. "Direct Gear Design for Asymmetric Tooth Gears". In Theory and Practice of Gearing and Transmissions, 117–43. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19740-1_7.

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Dobreva, Antoaneta. "Theoretical Investigation of the Energy Efficiency of Planetary Gear Trains". In Power Transmissions, 289–98. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6558-0_21.

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Atti di convegni sul tema "Gear transmissions"

Darmstadt, Patrick, e Mark Robuck. "Composites for Advanced Drive Systems, a Systems Analysis Revolutionary Vertical Lift Technology (RVLT)". In Vertical Flight Society 74th Annual Forum & Technology Display, 1–16. The Vertical Flight Society, 2018. http://dx.doi.org/10.4050/f-0074-2018-12862.

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Rotorcraft propulsion systems are continually looking to improve power density; that is reducing weight and increasing power capacity and efficiency. In order to advance rotorcraft propulsion system technology, NASA Glenn Research Center (NGRC) contracted Boeing Vertical Lift to perform system level benefit assessments of designing composite materials into rotorcraft transmission gear and shaft systems. In general, the environment inside a typical rotorcraft transmission creates issues for typical composite materials. In flight critical gears and shafts, design challenges and safety risks associated with introducing composite materials must be understood and accounted for in the design. Boeing was able to develop a technical approach for the system study that covered a relatively large population of rotorcraft main transmissions. This technical approach evaluated rotorcraft from various size classes and configurations and applied parametric estimating methods to assess the performance impact of composite hybrid technologies inside transmissions, in the rotating frame. Parametric weight estimating showed that composite hybrid technologies account for an average 9% weight savings over the baseline transmissions. More weight savings may be observed when various other aircraft systems are considered. Tandem and Tilt-rotor aircraft use similar transmissions at the forward/aft rotor head and left/right side of the aircraft, respectively, doubling estimated weight savings of a single transmission. Other aircraft systems, such as airframe, landing gear, and fuel systems benefit from reduced propulsion system weight, and, therefore, lighter weight aircraft are possible when propulsion system weight is reduced. In this paper, a systems level technical approach is summarized which was used to assess the performance impacts of introducing composite materials inside helicopter transmissions, in the rotating frame. Existing composite technologies, technical challenges, and general material selection guidance were used to develop the technical approach. Transmissions from a multitude of rotorcraft configurations and power classes were studied to build a database of expected performance gains. Component designs were developed using composite materials to varying levels of fidelity in order to develop data used for parametric weight estimating. The component designs are compiled and averaged with similar, existing designs in order to build a robust dataset for weight estimating purposes. Using information developed during the component design phase, technical challenges were defined.

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LaBerge, Kelsen, Robert Handschuh, Gary Roberts e Scott Thorp. "Performance Investigation of a Full-Scale Hybrid Composite Bull Gear". In Vertical Flight Society 72nd Annual Forum & Technology Display, 1–7. The Vertical Flight Society, 2016. http://dx.doi.org/10.4050/f-0072-2016-11520.

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Hybrid composite gears have been investigated as a weight saving technology for rotorcraft transmissions. These gears differ from conventional steel gears in that the structural material between the shaft interface and the gear rim is replaced with a lightweight carbon fiber composite. The work discussed here is an extension of previous coupon level hybrid gear tests to a full-scale bull gear. The NASA Glenn Research Center High-Speed Helical Gear Rig was modified for this program, allowing several hybrid gear web configurations to be tested while utilizing the same gear rim. Testing was performed on both a baseline (steel) web configuration and a hybrid (steel-composite) configuration. Vibration, orbit and temperature data were recorded and compared between configurations. Vibration levels did not differ greatly between the hybrid and steel configurations, nor did temperature differential between inlet and outlet. While orbit shape displayed differences between the hybrid and baseline configurations, the general overall amplitude was comparable. The hybrid configuration discussed here successfully ran at 3300 hp (2,460 kW), however, progressive growth of the orbit while running at this test condition discontinued the test. Further studies are planned to determine the cause of this behavior.

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Litvin, F. L., J. C. Wang, R. B. Bossler, Y. J. D. Chen, G. Heath e David G. Lewicki. "Application of Face-Gear Drives in Helicopter Transmissions". In ASME 1992 Design Technical Conferences. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/detc1992-0033.

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Abstract The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated.

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Choi, Sukhwan, e C. James Li. "Model Based Spur Gear Failure Prediction Using Gear Diagnosis". In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82482.

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Gears are common mechanical components used in power transmissions and frequently responsible for transmission failures. Since the crack size is not directly measurable while gear is in service, there is difficulty in predicting residual life of gears in service. The aim of this study is to present a prognostic methodology to predict the residual life of a cracked spur gear that is in service utilizing 2D FEM/fracture mechanics based failure model. The previously developed gear diagnostic algorithms and artificial neural network were employed to estimate crack size from measured gear vibration. The predicted results were validated with experimental data. Experimental results showed that the method had an averaged error of 12.94% in its estimate of remaining life.

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Starzhinsky, Victor E., Yuri L. Soliterman e Arcadi M. Goman. "Reliability Prediction of Gear Transmissions". In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34103.

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Service life of any individual transmission gears is known to represent a stochastic value. The methods of predicting gearing reliability as a relation of the acting and permissible stress distributions are described. The probability of transmission gear non-failure service is considered with most characteristic failure modes such as the tooth breakage and plastic deformation of the tooth working surfaces under a short-term maximal dynamic loading and the bending and contact fatigue under prolonged service loads. The employment of different statistical distribution parameters for gear reliability prediction is considered. A practical example of gearing reliability prediction is given.

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Beauchesne, Dennis. "Heat Treating of EV Transmissions". In HT2021. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.ht2021p0081.

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Abstract As consumers embrace Electric Vehicle (EV) technology, the automotive industry is moving quickly into replacing internal combustion engines (ICE) and traditional transmissions. The change to electrically driven vehicles offers new challenges to the gear manufacturing world, and most importantly new specifications to heat treat these gears - specifically quieter gear sets and higher torque ratings. Today’s EVs have a much lower tolerance for noise from the gear set to power the vehicle; therefore, this continues the need for even quieter and stronger gears. This technical presentation will illustrate the heat treat and distortion specifications for these new gears, along with answering the “why” of selecting low pressure vacuum carburizing (LPC) for new programs around the world.

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Tuller, Zachary, Nadirsh Patel e McKenzie Walsh. "Optimum Shifting of Hybrid and Battery Electric Powertrain Systems with Motors before and after a Transmission". In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2024. http://dx.doi.org/10.4271/2024-01-2143.

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<div class="section abstract"><div class="htmlview paragraph">This paper proposes an optimization-based transmission gear shifting strategy for electrified powertrains with a transmission. With the demand for reduced vehicle emissions, electrified propulsion systems have garnered significant attention due to their potential to improve vehicle efficiency and performance. An electrified propulsion system architecture of significance includes multiple electric motors and a transmission where some driveline actuators can transmit torque through changing gear ratios. If there is at least one electric motor arranged before the input of the transmission and at least one after the transmission output, a unique design opportunity arises to shift gears in the most energy efficient manner. An optimization-based gear shifting strategy is proposed where torque through the transmission is offloaded to the electric motor arranged after the transmission’s output, the transmission shifts gears with less torque transmitted through it, then the base optimization strategy is resumed after the gear shift. This optimization strategy improves energy efficiency by reducing clutch losses during the torque and speed phases of the gear shift.</div><div class="htmlview paragraph">The optimization solution for shifting gears in electrified powertrain systems with transmissions is described starting with an analysis of electrified powertrains that can implement this strategy. The optimization-based strategy is described in detail, showing the propulsion system maximizes energy efficiency considering a variety of operating conditions and gear shifting methods. Propulsion system efficiency is presented with an emphasis on electric motor power losses and clutch losses. Finally, a variance analysis is presented showing the impact of system parameters such as gear ratio spread on optimization.</div></div>

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Bo¨rner, J., K. Humm e F. Joachim. "Development of Conical Involute Gears (Beveloids) for Vehicle Transmissions". In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/ptg-48089.

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Conical involute gears (beveloids) are used in transmissions with intersecting or skew axes and for backlash-free transmissions with parallel axes. Conical gears are spur or helical gears with variable addendum modification (tooth thickness) across the face width. They can mesh with all gears made with the same tool. The geometry of such gears is generally known, but applications in power transmissions are more or less exceptional. ZF applications so far include marine transmissions with inclined output shafts and low backlash robot transmissions. The latest development has been realized for the AWD version of a six-speed automatic transmission. Here, the torque must be transmitted from a center differential to a front-axle bevel gear. By means of conical spur gears, it has been possible to realize an inclined drive shaft which offers considerable advantages in terms of installation space. This lecture deals with the development of conical gears for vehicle transmissions: basic geometry, design, production and testing.

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Hurrell, Michael, e Irebert Delgado. "Swept Volume Approach for the Characterization of Pumping Loss of Shrouded Meshed Cylindrical Gears". In Vertical Flight Society 75th Annual Forum & Technology Display. The Vertical Flight Society, 2019. http://dx.doi.org/10.4050/f-0075-2019-14681.

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High speed rotorcraft transmissions are subject to load-independent power losses consisting of drag and pumping loss. Tightly conforming shrouds enclosing the transmission gears are often incorporated to reduce the drag component of the total load independent losses. However, tightly conforming axial shrouding can result in an increase in the pumping loss component. Quantifying the pumping loss of shrouded gear transmissions has been the subject of many studies. This study presents a new approach for estimating pumping loss based on the concept of swept volume borrowed from the positive displacement pump and compressor industry. In this study, pumping loss of shrouded gear transmissions is considered to be related to the swept volume of the gear sets and the downstream flow resistance created by the shroud clearances. The drag loss and pumping loss of a spur gear pair have been determined through testing using the NASA Glenn Research Center Gear Windage Test Facility. The results from this testing have been compared to theoretical results using the formulations presented in this study. Good correlation exist between the test pumping power loss and the predicted pumping power loss for tightly conforming axial shroud configurations.

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Jáuregui, Juan Carlos, e Rodrigo López Sansalvador. "Criteria for the Design of High Efficiency Planocentric Transmissions". In ASME 1992 Design Technical Conferences. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/detc1992-0325.

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Abstract In this paper, the design criteria for high efficiency planocentric transmissions is presented. The space solution of a single stage planocentric transmission is limited by geometric constraints. These constraints are produced basically by the interference between pinion teeth and gear teeth. Special interest is focused on the interferences of internal gears and a detailed analysis of the influence of teeth parameters, such as addendum coefficient and pressure angle, is included. Conclusions are drawn from the analysis of the interferences and a design criteria is outlined. It was found that the space solution can be wider if pinion and gear are designed with stub teeth and high pressure angle.

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Rapporti di organizzazioni sul tema "Gear transmissions"

Litvin, F. L., J. C. Wang, R. B. Bossler, Chen Jr., Heath Y. J. e G. Application of Face-Gear Drives in Helicopter Transmissions. Fort Belvoir, VA: Defense Technical Information Center, gennaio 1992. http://dx.doi.org/10.21236/ada257727.

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Parker, Robert. Analytical/Computational Investigation of Planetary Gear Dynamics in Rotorcraft Transmissions. Fort Belvoir, VA: Defense Technical Information Center, agosto 2008. http://dx.doi.org/10.21236/ada499395.

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Cao Romero, Julio A., Jorge Reyes-Avendaño, Julio Soriano, Leonardo Farfan-Cabrera e Ali Erdemir. A Pin-on-Disc Study on the Electrified Sliding Wear of EVs Powertrain Gears. SAE International, marzo 2022. http://dx.doi.org/10.4271/2022-01-0320.

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In contrast to conventional powertrains from internal combustion engine vehicles (ICEV), the tribological performance of powertrains of electric vehicles (EVs) must be further evaluated by considering new critical operating conditions such as electrical environments. The operation of any type of electric motor produces shaft voltages and currents due to various hardware configurations and factors. Furthermore, the common application of inverters intensifies this problem. It has been reported that the induced shaft voltages and currents can cause premature failure problems in tribological components such as bearings and gears due to accelerated wear and/or fatigue. It is ascribed to effects of electric discharge machining (EDM), also named, sparking wear caused by shaft currents and poor or increasingly diminishing dielectric strength of lubricants. A great effort has been done to study this problem in bearings, but it has not yet been the case for gears. Considering that EVs powertrains can be configurated with an electric motor coupled to a single-speed or multi-speed transmission, it is expected that shaft currents can also affect gears to some extent. The pin-on-disc test has been widely used to study sliding wear of gear materials under comparable or realistic operating conditions. This accelerated test is effective for screening materials, lubricants and operating conditions allowing evaluations of their friction and wear properties. However, it has not been implemented for studying gear materials under electrified environments. Thus, this paper aims to explore the friction coefficient and wear of gear materials under non-electrified and electrified sliding in a pin-on-disc tester applying typical of EVs powertrain shaft currents during sliding. The tests were carried out at two different DC currents under comparable gear dry and lubricated sliding contact conditions. Friction coefficient, wear volumes and morphologies were evaluated and reported in this work.

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Korendyasev, G. AUTOMATIC TRANSMISSION GEAR SHIFTS ANALYSIS AT LOW SPEEDS OF THE VEHICLE. Journal Article published January 2020 in Bulletin of Science and Technical Development issue 149, 2020. http://dx.doi.org/10.18411/vntr2019-149-4.

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Korendyasev, G., K. Salamandra e L. Tyves. AUTOMATIC TRANSMISSION GEAR SHIFTS ANALYSIS AT LOW SPEEDS OF THE VEHICLE. Journal Article published January 2020 in Bulletin of Science and Technical Development issue 149, 2020. http://dx.doi.org/10.18411/vntr2019-149-41.

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Skoglund, Paul, Ola Litstrom e Anders Flodin. Improvement of Powder Metallurgy Gears for Engines and Transmissions. Warrendale, PA: SAE International, ottobre 2013. http://dx.doi.org/10.4271/2013-32-9102.

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Kaneko, Yutaka, Kazutaka Adachi, Kimio Kanai e Yoshimasa Ochi. Design of a Gear Ratio Servo Control System for Toroidal Continuously Variable Transmission. Warrendale, PA: SAE International, maggio 2005. http://dx.doi.org/10.4271/2005-08-0040.

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Rao, Suren B., e Nagesh Sonti. High Strength P/M Gears for Vehicle Transmissions - Phase 2. Fort Belvoir, VA: Defense Technical Information Center, agosto 2008. http://dx.doi.org/10.21236/ada486131.

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Kumar, T. M. Manoz, Mohan Gangadurai, Vinayak Kathare e V. Pattabiraman. Optimization of a Manual Transmission Gear Ratios for a Small Cargo Carrier using Statistics-Based Simulation Techniques. Warrendale, PA: SAE International, ottobre 2005. http://dx.doi.org/10.4271/2005-32-0001.

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