Jose Pedrero

• National University of Distance Education

This paper presents a discussion on the geometrical constraints of internal spur gear teeth, namely the teeth pointing, root interference, pitch interference and tip interference. The influence of the geometrical parameters of the gears, as the teeth height, center distance, shift coefficients and backlash allowance, has been studied, as well as th...

The extension of the contact interval resulting from loaded tooth deflections and local contact deformations increases the effective contact ratio, which can exceed the value of 2 if the theoretical contact ratio is close to 2, as frequently occurs in internal spur gears. In these cases, the load is shared by at least two pairs of teeth throughout...

Rack and pinion drive systems are widely used in machine tools with long travel distances because the stiffness is independent of the travelled distance, in contrast to other drive systems such as ballscrews. Although the inherent backlash problem of gear systems has been solved by means of utilizing two pinions independently preloaded, the time-va...

En engranajes de transmisión de potencia, la geometría de las superficies en contacto tiene influencia en la rigidez de engrane y el error de transmisión, que a su vez es origen de sobrecarga dinámica, ruido y vibración. Las alteraciones en la geometría de los perfiles, como el rebaje de punta para evitar el impacto de inicio de engrane o el desgas...

In this paper, we present a learning experience for the improvement of kinematic and dynamic cam analysis teaching through the development of a collaborative project among subject students, based on the realisation of an application in Excel using its ease of use and matrix calculation capacity. For the examination of various cam types, motion prog...

This paper presents a discussion on the influence of the tip relief on the tip interference and contact ratio, as well as a methodology to select proper values of the teeth heights, center distances, rack shift coefficients, and tip reliefs to ensure maximum values of the contact ratio while avoiding tip interference, root interference and pitch in...

Power transmission systems are subjected, under operating conditions, to diverse kinds of loads. Their failure is studied, from a theoretical point of view, in Machine Design subjects in Engineering Schools. This paper presents the procedure, proposed to students who study the subject through distance education, for modelling and analysing the stre...

Foreword The International Conference on Gears in Garching near Munich, Germany, is an established platform for researchers on and manufacturers of gears and transmission systems. At the 10th issue of the conference in September of 2023, gear experts discussed the latest developments and research results from the powertrain industry and academia. G...

Mechanical efficiency is not a critical design factor of wind turbine gearboxes since wind energy is abundant and costless. The design and sizing of the gears will be determined by the requirements of power density, gear ratio, fatigue safety, and allowable noise and vibration levels. However, reducing power losses results in lower lubricant heatin...

Para la simulación del contacto entre dientes de engranajes helicoidales es necesaria una precisa determinación de la longitud de la línea de contacto, que es variable a lo largo del ciclo de engrane. Esta variación viene influenciada no sólo por la inclinación de las líneas, sino también por su alargamiento debido al adelanto del inicio del contac...

Improving the mechanical efficiency is not the most important objective in the design of wind turbine gearboxes since the available wind energy is abundant and costless. The most important criteria for dimensioning the gearbox are the fatigue strength—bending and pitting—, noise emission, vibrations, and maintenance requirements. Nevertheless, mech...

Planetary gear sets are suitable for high power density and gear ratio, but this means high torques and stress levels. Though the torque is transmitted between multiple planets, it is not evenly distributed among them due to manufacturing and assembly errors. The torque is greater than the average value in some planets, and smaller in the others, w...

The determination of the load sharing, meshing stiffness, and transmission error is essential for evaluating the behavior of the gear pair in such important aspects as the strength, dynamic load, load carrying capacity, and noise and vibrations levels. The use of computational techniques as the Finite Element Method provides accurate results, but i...

The gear mesh stiffness, and therefore the load sharing, tooth deflections, and transmission error, are strongly influenced by the tooth dimensions and profile shape. But the profile shape and contact conditions are affected by the wear produced by the relative sliding of the teeth surfaces, so that load sharing and transmission error change as the...

The loaded tooth deflections, manufacturing deviations, and assembly errors on spur gears induce a delay on the driven gear respect to the driving gear, which is called loaded transmission error. This delay causes an earlier start of contact outside the pressure line, resulting in a mesh-in impact, which is an important source of noise and vibratio...

A simple, analytical model for load sharing and quasi-static transmission error of spur gears with non-standard tooth height is presented. It is based on the minimum elastic potential energy principium and considers the influence of profile modifications and tooth deflections. In addition, is suitable for different tooth height on pinion and wheel,...

This paper presents a study on the influence on the quasi-static transmission error of symmetric long profile modifications on high contact ratio spur gears. A previously developed model for the load sharing ratio and quasi-static transmission error, based on the hypothesis of equal delay interval in all the teeth in simultaneous contact, has been...

The geometry of the gear teeth, as well as that of the tooth contact, is complex and not easy to simulate. Thus, computer aided techniques, as finite element analyses or complex tooth contact analyses, should be applied for strength calculations or simulations of contact conditions. These techniques provide reliable results, but usually requires lo...

A comparison among different approaches of the meshing stiffness of spur gears has been carried out. The influence of each one on the load sharing, and subsequently on the determinant tooth-root and contact stresses, has also been studied. Equations for the evolution of the meshing stiffness along the path of contact according to all these formulat...

The start of contact between loaded involute gear teeth occurs before reaching the theoretical inner point of contact due to the load-induced deflections of previous tooth pairs in contact. This sooner contact occurs outside the pressure line and produces a shock between the driving tooth root and the driven tooth tip, which induces noise, vibratio...

The meshing stiffness, load sharing ratio, and quasi-static transmission error of spur gear pairs are related to each other and are dependent on tooth geometry. In addition, profile modifications influence the contact conditions, because modified profile points may only contact under load conditions and owing to load-induced elastic deflections. Ho...

An enhanced model for strength calculations of internal spur gear pairs is presented. The load sharing among couples of teeth in simultaneous contact is determined from the meshing stiffness, whose value has been calculated at any point of the path of contact, considering bending, compressive, shear and Hertzian deflections. This curve of variation...

Profile modifications are often used on gear teeth to ensure a smooth start of contact, avoiding noise, vibrations and dynamic loads induced by a sooner contact outside the pressure line which occurs due to unavoidable tooth deflections under load. A suitable tip relief on the driven gear teeth delays the start of contact, locating it at the approp...

Profile modifications are commonly used to avoid shocks between meshing gear teeth produced by the delay of the driven gear, and the subsequent sooner start of contact, due to the teeth deflections. A suitable tip relief at the driven tooth shifts the start of contact to the proper location at the theoretical inner point of contact. The shape of th...

Der Bericht ist ausschließlich als PDF-Dokument erschienen! Drei Konferenzen in einer, auf 1.874 Seiten finden Sie jede Menge aller neueste Informationen zum Thema Gears. Die beiden anderen Konferenzen waren: 3rd International Conference on High Performance Plastic Gears 2019 und 3rd International Conference on Gear Production 2019 Achtung: Dieser...

In this paper, the meshing stiffness of spur gear pairs, considering both global tooth deflections and local contact deflections, is evaluated at any point of the path of contact and approximated by an analytical, simple function. With this function, the load sharing ratio is calculated and compared with previous results obtained from the hypothesi...

Several models for the study of the meshing stiffness of spur gears have been recently developed, which have been applied to the determination of the load sharing among teeth, the dynamic behaviour, etc. Different geometries have been considered for different objectives: form the theoretical conjugate contact to consider tooth deflections, asymmetr...

Power losses in any geared-transmission can be attributed to gear-mesh and bearing-contact frictional effects and the interaction of rolling element bearings and gears with the lubricating medium. In this paper, a composite power loss model combining a non-uniform load distribution model with a local friction coefficient at any point of contact and...

Talking about the design of modern high-performance power train applications, one of the essential components to focus on are the gears. Gears convert torque and speed in a very wide power range, at low cost and with minimal losses and noise emission. However, the demands regarding cost, power density, NVH-behavior and efficiency are steadily incre...

In this paper the determinant load conditions for bending and pitting calculations, for involute, internal spur gears have been established. Calculations are based on a new model of load distribution, which takes into account the changing rigidity of the pair of teeth along the path of contact. This model has been obtained from the minimum elastic...

This paper presents a model of load sharing for high contact ratio internal spur gears, which takes into account the changing rigidity of the pair of teeth along the path of contact. It has been obtained from the minimum elastic potential energy criterion, resulting in a non-uniform load distribution among several tooth-pairs in simultaneous contac...

For contact stress calculations of spur and helical gears, the Hertz equation can be used in combination with a model of load distribution along the line of contact. This load distribution is not uniform due to the changing rigidity of the pair of teeth along the path of contact and has decisive influence on the location and the value of the critic...

The presence of undercut at the tooth root, non-equal addendum on pinion and wheel, non-standard tooth height or non-standard center distance may have decisive influence on the load distribution along the line of contact of spur and helical gear teeth. The curve of variation of the meshing stiffness along the path of contact, quite symmetric respec...

Simple, traditional methods for computation of the efficiency of spur gears are based on the hypotheses of constant friction coefficient and uniform load sharing along the path of contact. However, none of them is accurate. The friction coefficient is variable along the path of contact, though average values can be often considered for preliminary...

The presence of undercut at the tooth root, non-equal addendum on pinion and wheel, non-standard tooth height or non-standard center distance may have decisive influence on the load sharing between pairs of teeth in simultaneous contact of spur gears. The curve of variation of the meshing stiffness along the path of contact, quite symmetric respect...

The presence of undercut at the pinion root may affect the load sharing among couples of spur gear teeth in simultaneous contact, as well as the load distribution along the line of contact of helical gears. This occurs if the outside points of the wheel profile do not find, due to undercut, mating profile to mesh with, which is called vacuum gearin...

Calculation methods of spur and helical gear drives for preliminary designs or standardization purposes available in technical literature, use the Hertz equation to evaluate the contact stress, assuming the load to be uniformly distributed along the line of contact. However, this model presents some discrepancies with experimental results because t...

An analytic model to compute the efficiency of spur gears has been developed. It is based on the application of a non-uniform model of load distribution obtained from the minimum elastic potential criterion and a simplified non-uniform model of the friction coefficient along the path of contact. Both conventional and high transverse contact ratio s...

Calculation methods of spur and helical gears for preliminary designs or standardization purposes available in technical literature use simple equations given by the linear theory of elasticity (Navier’s equation) and the Hertzian contact model to evaluate the bending and contact stresses, assuming the load to be uniformly distributed along the lin...

The traditional methods for computation of the efficiency of cylindrical gear transmissions are based on the hypotheses of constant friction coefficient and uniform load distribution along the line of contact. However, the changing rigidity of the pair of teeth along the path of contact produces a non-uniform load distribution, which has significan...

The traditional methods for computation of the efficiency of cylindrical gear transmissions are based on the hypotheses of constant friction coefficient and uniform load distribution along the line of contact. However, the changing rigidity of the pair of teeth along the path of contact produces a non–uniform load distribution, which has significan...

Calculation methods of spur and helical gear drives with a transverse contact ratio higher than 2, accurate enough for preliminary designs or standardization purposes, are not available in technical literature. If the load is assumed to be uniformly distributed along the line of contact, simple equations given by the linear theory of elasticity and...

This paper presents a new model of load distribution for involute, internal gear drives, which takes into account the changing rigidity of the pair of teeth along the path of contact. The model has been obtained from the minimum elastic potential criterion, resulting in a non-uniform load distribution along the line of contact (for helical gears),...

An enhanced approach for the application of longitudinal plunging in the manufacturing of a double crowned pinion of a face gear drive has been investigated, with the purpose of reducing the sensitivity of the gear drive to misalignments. The process of manufacturing is based on a modification of the movements applied to the grinding disk during th...

A stress analysis based on the Finite Element Method of a face gear drive with conical pinion is presented. The main goal of the stress analysis is to compare the bending stresses of the gear drives with conical and spur pinion, in order to verify the results obtained in previous investigations based on the concept of resistance coefficient. The ap...

An approximate equation for accurate determination of the inner point of the involute profile of undercut spur and helical gear teeth is presented. This point may have influence on the effective path of contact and consequently on the contact ratio, the length of the path of contact and the stress levels, which should be taken into account for calc...

The authors present a new method for establishing the relations between the primitive surfaces and the teeth basic surfaces in a gear transmission. This new approach allows to make the synthesis not only by considering as known the gear pitch radius, or what is the same, its transverse module, as existing approaches, but also from the normal module...

This paper represents an enhanced approach for application of longitudinal plunging in the manufacturing process of spur gear drives in order to localize the bearing contact. The proposed approach is based on application of a grinding disk performing a planar curvilinear trajectory. The main innovation is the tilt of the plane containing the curvil...

The minimum number of teeth to avoid undercut on involute spur and helical gears depends on the pressure angle, among some other geometrical parameters. Higher number of teeth is required if the pressure angle becomes smaller. However, the contact ratio may be increased by reducing the pressure angle, which means the load is distributed along a lon...

In this work, new approaches for the dimensional synthesis of both tooth and operating basic surfaces for hyperbolic gear transmissions are presented. Both traditional worm-gearing hyperbolic transmissions (point contact) and non-traditional ones (line contact) are considered regarding constraints as the manufacturing method, the standardized tool...

The methods currently available for the determination of the AGMA J-factor require iterative procedures in order to compute the value of the critical section parameter, which is necessary to compute the tooth thickness at the critical section and the height of the Lewis parabola. This paper presents an approximate, non-iterative method for the dete...

Se presenta un método numérico para la determinación del mapa tensional en la zona de contacto entre dos cuerpos, a partir de la distribución de presiones sobre la superficie. Este método permite determinar el campo de tensiones cerca de la superficie. Se ha aplicado a las superficies lubricadas donde la picadura es el tipo de fallo más usual en co...

To estimate the bending stress at the root of a loaded gear tooth, ISO/TC-60 introduced the tooth form factor and the stress concentration factor, which were both defined as a function of the tooth thickness at the critical section and the distance between this section and the intersection of the line of action and the tooth centerline, when load a...

An optimization study on the design of two-step gearboxes, based on the maximum safety, and thus maximum life criterion is presented. A computer aided design tool (CAD), which gives the graphic representation of the variation of both safety factors for bending and wear of every step has been developed. Using this tool, a parametric analysis of the...

A simple, analytical method to estimate the addendum modification factors for gears designed to have balanced specific sliding is presented, which is valid for every value of the pressure angle and the addendum. Since the method requires neither iterations nor tabular values, it is extremely efficient for computer applications.

An approximate equation for the relation between pinion and gear addendum modification factors for gears to have a pre-establishedb value of the contact ratio, is given. A method to estimate those factors when the additional condition of balanced specific sliding is imposed, is also presented. Both equations are valid for every value of the pressur...

In this paper a graphic method for the analysis of the design of spur and helical gears is presented. The analysis is made by means of some diagrams which show the influence of the initial parameters on the design. Since the graphics are different for every problem, a computer program has been developed in order to make them. The results enable spe...

In the present environment of the computer aided manufacturing, and in order to penetrate in the computer integrated manufacturing (CIM), it is very interesting to think over the computer assisted quality control or, more precisely, to enter in the computer aided quality system (CAQ). This paper analyses, from a CIM environment perspective and in a...

In this paper we analyze the cold forging process of metallic materials made with mechanical presses. The main mechanical, dimensional and kinematic aspects of the process are studied. The concept of tolerance is also incorporated to obtain a more industrial view of the process.

2 и 2,5. Изведени су кључни услови оптерећења и израчунати су номинални напони у подножју зубаца. Reliable calculation methods of the bending load capacity for spur and helical gears with high transverse contact ratio are not available in technical literature. Simple equations given by the linear theory of elasticity are not in good agreement with...

Basándose en el principio de mínima energía de deformación se ha obtenido el reparto de carga entre los distintos puntos en contacto entre dos cuerpos, utilizando dos instrumentos de minimización de la energía: las condiciones de Kuhn-T¨ucker y los Multiplicadores de Lagrange. Se ha deducido una expresión matricial directa y sencilla, sin recurrir...