Analysis of an Improved Planetary Gear-Transmission Bearing

1964 ◽  
Vol 86 (3) ◽  
pp. 457-461 ◽  
Author(s):  
T. A. Harris ◽  
J. L. Broschard
Keyword(s):  
Fatigue Life ◽  
Gear Tooth ◽  
Roller Bearing ◽  
Planetary Gear ◽  
Major Axis ◽  
Rolling Bearing ◽  
Load Application ◽  
Outer Ring ◽  
Rolling Element ◽  
Oriented Parallel

In planetary-gear transmissions, especially for aircraft applications, the planet gears are frequently made integral with the outer rings of rolling bearings. Thus the outer ring of the rolling bearing is subjected to the tangential, radial, and moment loading attendant to spur gears. If the outer ring of the bearing is relatively thin, the distortion induced therein by the gear forces alters the distribution of load from that of a roller bearing with a rigid outer ring, causing a significant reduction in the bearing fatigue life. Since the maximum rolling-element loads in the bearing occur in close angular proximity of the points of load application, it would appear that the magnitude of these rolling-element loads may be diminished and fatigue life subsequently increased by selectively applying clearance between rolling elements and raceway at the points of load application. In fact, theoretical analysis of a planetary-gear bearing having an out-of-round inner ring, wherein the major axis is oriented parallel to the tangential gear-tooth load, indicates that a condition of optimum clearance and out-of-round exists with respect to bearing fatigue life. An increase in fatigue life of approximately 40 percent is indicated with only a nominal amount of out-of-round.

Analysis of a Rolling-Element Idler Gear Bearing Having a Deformable Outer-Race Structure

1963 ◽  
Vol 85 (2) ◽  
pp. 273-278 ◽  
Author(s):  
A. B. Jones ◽  
T. A. Harris
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Roller Bearing ◽  
Rolling Element Bearing ◽  
Outer Ring ◽  
Outer Race ◽  
Rolling Element ◽  
Rolling Elements ◽  
Planet Gear ◽  
Bearing Rings

Conventional calculations of ball and roller bearing carrying capacity and fatigue life assume that the raceway bodies are rigid structures and that all elastic deformation occurs at the rolling elements’ contact with the raceways. In many instances, and particularly with aircraft applications, the bearing rings and their supports cannot be considered rigid. One such application is the planet gear in a transmission. This report develops a theory whereby the effects of the elastic distortions of the outer race of a rolling-element bearing on the internal load distribution and fatigue life of the bearing can be considered. The theory has been programmed for a high-speed, digital computer. An example of calculation for a planet gear roller bearing whose outer race is integral with the gear and of relatively thin section is given. The distortions of the flexible outer ring cause a significantly lower bearing fatigue life (L10) than would occur if the outer ring were rigid and considering a practical range of bearing diametral clearances. Mr. Jones developed the theoretical analysis for this paper and Mr. Harris provided the programming and the experimental data.

A New Quasi-Static Cylindrical Roller Bearing Model to Accurately Consider Non-Hertzian Contact Pressure in Time Domain Simulations

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Simon Kabus ◽  
Michael R. Hansen ◽  
Ole Ø. Mouritsen
Keyword(s):  
Fatigue Life ◽  
Time Domain ◽  
Roller Bearing ◽  
Rolling Bearing ◽  
Elastic Half Space ◽  
Hertzian Contact ◽  
Fatigue Life Analysis ◽  
Cylindrical Roller Bearing ◽  
Six Degree Of Freedom ◽  
Cylindrical Roller

The accuracy of the fatigue life calculations in rolling bearing simulations is highly dependent on the precision of the roller-raceway contact simulations. Several different methods exist to simulate these pressure distributions and in time domain bearing simulations, where many contacts need evaluation, the simple and time efficient methods are more popular, yielding erroneous life estimates. This paper presents a new six degree of freedom frictionless quasi-static time domain cylindrical roller bearing model that uses high precision elastic half-space theory to simulate the contact pressures. The potentially higher computational demand using the advanced contact calculations is addressed by preprocessing a series of contacts at different centerline approaches and roller tilt angles, which are used for interpolating contact results during time domain simulations. It is demonstrated that this new model allows for simulation of bearing misalignments, roller centrifugal forces, and flange contact induced roller tilt moments, and that the effect of these conditions is directly evaluated in a detailed fatigue life analysis. Finally, the stiffness of the bearing model is validated against existing experimental data with good correlation.

Research of Rolling Bearing Fault Feature Extraction Based on EMD and Choi-Williams

2013 ◽  
Vol 694-697 ◽  
pp. 1377-1381
Author(s):  
Xing Chun Wei ◽  
Yu Lin Tang ◽  
Tao Chen
Keyword(s):  
Feature Extraction ◽  
Vibration Signal ◽  
Rolling Bearing ◽  
Outer Ring ◽  
Intrinsic Mode Functions ◽  
Linear Superposition ◽  
Time Frequency ◽  
Bearing Fault ◽  
Rolling Element ◽  
Bearing Vibration

Aiming at rolling bearing fault signal of the non stationary feature, Apply a new method to the rolling bearing vibration signal of feature extraction, which is combined the Empirical Mode Decomposition (EMD) and the Choi-Williams distribution. Firstly, original signals were decomposed into a series of intrinsic mode functions (IMF) of different scales. To the decomposed each IMF component for Choi-Williams time-frequency analysis, Then take the linear superposition, finally obtained the rolling bearing vibration signal of Choi-Williams distribution. After the analyses of the rolling bearing inner ring, outer ring and rolling element fault signal ,the results show that this method can effectively suppress the frequency aliasing and interference caused by cross terms. And be able to accurately extract the fault frequency of the bearing inner ring, outer ring and rolling element, lay the foundation for the subsequent rolling bearing state recognition.

scholarly journals A new approach for the load calculation of the most loaded rolling element for the rolling bearing with internal radial clearance - The case study

2020 ◽  
Author(s):  
Radoslav Tomović
Keyword(s):  
Roller Bearing ◽  
Rolling Bearing ◽  
Radial Clearance ◽  
Practical Application ◽  
New Approach ◽  
Load Factors ◽  
Proposed Model ◽  
Rolling Element ◽  
Load Calculation

Abstract In this paper is presented a case study which has the goal to show the benefits of the application of a new approach for the calculation of load of the most loaded rolling element at the rolling bearing with the internal radial clearance. The calculation is based on the so-called load factors. By multiplication load factors with the value of the external radial load, the load which is transferred by the most loaded rolling element of the bearing is obtained. The case study is made for two types of bearings, the ball, and roller bearing. Obtained results were compared with the results obtained based on the calculation using some of the most commonly used methods so far. The analysis showed greater precision of the considered model with the same or much simpler application. For this reason, the proposed model is considered very suitable for practical application.

An Experimental Evaluation of High-Cycle Gear Tooth Bending Fatigue Lives Under Fully Reversed and Fully Released Loading Conditions With Application to Planetary Gear Sets

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Isaac J. Hong ◽  
Ahmet Kahraman ◽  
Neil Anderson
Keyword(s):  
Fatigue Life ◽  
Gear Tooth ◽  
Planetary Gear ◽  
Fatigue Tests ◽  
Experimental Methodology ◽  
Tooth Root ◽  
Loading Conditions ◽  
Bending Fatigue ◽  
Equivalent Number ◽  
Stress Ratios

Abstract High-cycle gear tooth bending fatigue lives of spur gears under fully reversed and fully released loading conditions are compared in this experimental study. The experimental methodology described in an earlier publication, (Hong et al. 2020, “A Rotating Gear Test Methodology for Evaluation of High-Cycle Tooth Bending Fatigue Lives Under Fully Reversed and Fully Released Loading Conditions,” Int. J. Fatigue, 133, p. 105432. 10.1016/j.ijfatigue.2019.105432), is employed to perform two sets of rotating, gear tooth bending fatigue tests. Statistical analyses are performed to regress stress versus life (S–N) curves under both loading conditions. These curves indicate that a gear under fully reversed loads has a shorter bending life at the same maximum tooth root stress as a gear under fully released loads. Various planetary gear set kinematic conditions with different stationary members are considered to determine the equivalent number of tooth loading cycles per revolution of the sun gear. They are combined with established S–N curves under both loading conditions to determine the ratios of allowable maximum tooth root stresses amongst the gear components of a P-planet gear set such that each gear in the set has the same bending fatigue life. A “stress-balanced” gear set designed to these stress ratios is expected to have the same bending fatigue life for its sun, ring, and planet gears, ensuring that the planetary gear set life is the longest.

scholarly journals Load Calculation of the Most Loaded Rolling Element for a Rolling Bearing with Internal Radial Clearance

2020 ◽  
Vol 10 (19) ◽  
pp. 6934
Author(s):  
Radoslav Tomović
Keyword(s):  
Ball Bearing ◽  
Roller Bearing ◽  
Rolling Bearing ◽  
Radial Clearance ◽  
Load Factor ◽  
New Model ◽  
Load Factors ◽  
Rolling Element ◽  
Load Calculation ◽  
Rolling Elements

This paper presents a new model for calculation of load for the most loaded rolling element in a rolling bearing with internal radial clearance. The calculation is based on a so-called load factor. By multiplying this factor by the value of the external radial load, the load transferred by the most loaded rolling element of the bearing is obtained. The values of the load factor are shown in the tables and diagrams, which makes the model very suitable for practical use. The load factors are shown for a ball bearing as well as for a roller bearing. The model considers two support positions of the inner ring on an even and odd number of rolling elements. The new model was compared with the most commonly used models up to now. The results showed greater accuracy of the studied model.

Applications of vibro-acoustic measurement and analysis in conjunction with tribological parameters to assess surface fatigue wear developed in the roller-bearing system

2021 ◽  
pp. 135065012098246
Author(s):  
Shashikant Pandey ◽  
Muniyappa Amarnath
Keyword(s):  
Roller Bearing ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Stribeck Curve ◽  
Fatigue Wear ◽  
Surface Fatigue ◽  
Rolling Element ◽  
Measurement And Analysis ◽  
Contact Surfaces ◽  
Bearing System

Rolling-element bearings are the most commonly used components in all rotating machinery. The variations in the operating conditions such as an increase in the number of operating cycles, load, speed, service temperature, and lubricant degradation result in the development of various defects such as pitting, spalling, scuffing, scoring, etc. The defects that appeared on rolling contact surfaces cause surface deterioration and change in the vibration and sound levels of the bearing system. The present experimental investigations are aimed at assessing the surface fatigue wear that appears on the contact surfaces of roller bearings. The studies considered the estimation of specific film thickness, analysis of surface fatigue wear developed on the rolling-element surfaces, surface roughness analysis, grease degradation analysis using Fourier transform infrared radiation, and vibration and sound signal measurement and analysis. The results obtained from the experimental investigation provide a good correlation between surface wear, vibration, and sound signals with a transition in the lubrication regimes in the Stribeck curve.

scholarly journals The Structure and Optimal Gear Tooth Profile Design of Two-Speed Transmission for Electric Vehicles

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3736
Author(s):  
Jae-Oh Han ◽  
Won-Hyeong Jeong ◽  
Jong-Seok Lee ◽  
Se-Hoon Oh
Keyword(s):  
Electric Vehicle ◽  
Electric Vehicles ◽  
Automobile Industry ◽  
Bending Strength ◽  
Gear Tooth ◽  
Planetary Gear ◽  
Maximum Speed ◽  
Compact Structure ◽  
Simple Method ◽  
Paris Climate Agreement

As environmental regulations have been strengthened worldwide since the Paris Climate Agreement, the automobile industry is shifting its production paradigm to focus on eco-friendly vehicles such as electric vehicles and hydrogen-battery vehicles. Governments are banning fossil fuel vehicles by law and expanding the introduction of green vehicles. The energy efficiency of electric vehicles that use a limited power source called batteries depends on the driving environment. Applying a two-speed transmission to an electric vehicle can optimize average speed and performance efficiency at low speeds, and achieve maximum speed with minimal torque at high speeds. In this study, a two-speed transmission for an electric vehicle has been developed, to be used in a compact electric vehicle. This utilizes a planetary gear of a total of three pairs, made of a single module which was intended to enable two-speed. The ring gear was removed, and the carrier was used in common. When shifting, the energy used for the speed change is small, due to the use of the simple method of fixing the sun gear of each stage. Each gear was designed by calculating bending strength and surface durability, using JGMA standards, to secure stability. The safety factor of the gears used in the transmission is as follows: all gears have been verified for safety with a bending strength of 1.2 or higher and a surface pressure strength of 1.1 or higher. The design validity of the transmission was verified by calculating the gear meshing ratio and the reference efficiency of the gear. The transmission to be developed through the research results of this paper has a simple and compact structure optimized for electric vehicles, and has reduced shift shock. In addition, energy can be used more efficiently, which will help improve fuel economy and increase drive range.

Investigation on the drag effect of a rolling element confined in the cavity of a cylindrical roller bearing

2021 ◽  
pp. 135065012110260
Author(s):  
Wenjun Gao ◽  
Shuo Zhang ◽  
Xiaohang Li ◽  
Zhenxia Liu
Keyword(s):  
Open Space ◽  
Roller Bearing ◽  
Flow Characteristics ◽  
Experimental Tests ◽  
Windward Side ◽  
Leeward Side ◽  
Drag Effect ◽  
Rolling Element ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

In cylindrical roller bearings, the drag effect may be induced by the rolling element translating in a fluid environment of the bearing cavity. In this article, the computational fluid dynamics method and experimental tests are employed to analyse its flow characteristics and pressure distribution. The results indicate that the pressure difference between the windward side and the leeward side of the cylinder is raised in view of it blocking the flow field. Four whirl vortexes are formed in four outlets of two wedge-shaped areas between the front part of the cylindrical surface and adjacent walls for the cylinder of L/ D = 1.5 at Re = 4.5 × 103. Vortex shedding is found in the direction of cylinder axis at Re = 4.5 × 104. The relationship between drag coefficient and Reynolds number is illustrated, obviously higher than that of the two-dimensional cylinder in open space.

Sign in / Sign up

Export Citation Format

Share Document