A mixed finite element and analytical method to predict load, mechanical power loss and improved efficiency in non-standard spur gear drives

2017 ◽  
Vol 231 (11) ◽  
pp. 1408-1424 ◽  
Author(s):  
R Prabhu Sekar ◽  
V Edwin Geo ◽  
Leenus Jesu Martin
Keyword(s):  
Power Loss ◽  
Mixed Finite Element ◽  
Mechanical Efficiency ◽  
Spur Gear ◽  
Gear Ratio ◽  
Accurate Estimation ◽  
Power Losses ◽  
Contributing Factors ◽  
Comparative Performance ◽  
Gear Efficiency

A reasonably accurate estimation of gear power loss is desirable to maximize gear performance. The load share by teeth pair, contact stress, sliding speed, elastohydrodynamic film thickness and coefficient of friction are some of the most important contributing factors which determine frictional power losses in gears. This paper presents an improvement concept to minimize the load-related power losses (sliding and rolling power losses), which will lead to an enhancement in gear efficiency by selection of non-standard gears. The tooth thickness at the pitch circle of the pinion and gear is different in non-standard gears (kpπm > 0.5 πm and kgπm < 0.5 πm), whereas it is equal in standard gears (kpπm = kgπm = 0.5 πm). In this work, the load share-based frictional power loss and the respective mechanical efficiency have been determined for comparative performance of standard and non-standard gears. Finally, the influence of various gear and drive parameters such as gear ratio, pressure angle pinion teeth number and addendum height factor on gear efficiency has also been investigated and the results of the parametric study are discussed.

An Experimental Methodology to Determine Components of Power Losses of a Gearbox

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
A. Dindar ◽  
K. Chaudhury ◽  
I. Hong ◽  
A. Kahraman ◽  
C. Wink
Keyword(s):  
Power Loss ◽  
Spur Gear ◽  
Rolling Element Bearing ◽  
Experimental Methodology ◽  
Total Power ◽  
Gear Pair ◽  
Rolling Element Bearings ◽  
Power Losses ◽  
Rolling Element ◽  
The One

Abstract In this study, an experimental methodology is presented to separate various components of the power loss of a gearbox. The methodology relies on two separate measurements. One is designed to measure total power loss of a gearbox housing a single spur gear pair under both loaded and unloaded conditions such that load-independent (spin) and load-dependent (mechanical) components can be separated. With the assumption that gear pair and rolling element bearings constitute the bulk of the gearbox power loss, a second measurement system designed to quantify rolling element bearing losses is proposed. With this setup, spin and mechanical power losses of rolling element bearings used in the gearbox experiments are measured. Combining the sets of gearbox and bearing data, power loss components attributable to the gear pair and rolling element bearings are quantified as a function of speed and torque. The results indicate that all gear and bearing related components are significant and a methodology such as the one proposed in this study is warranted.

scholarly journals Bearing Power Losses with Water-Containing Gear Fluids

Lubricants ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 5 ◽  
Author(s):  
Mustafa Yilmaz ◽  
Thomas Lohner ◽  
Klaus Michaelis ◽  
Karsten Stahl
Keyword(s):  
Power Loss ◽  
Stribeck Curve ◽  
Detailed Knowledge ◽  
Power Losses ◽  
Test Rig ◽  
Load Bearing ◽  
Gear Efficiency ◽  
Efficiency Test ◽  
Typical Calculation ◽  
Calculation Procedures

Lubricants have a large influence on gearbox power losses. Recent investigations at a gear efficiency test rig have shown the high potential of water-containing gear fluids in drastically reducing load-dependent gear losses and temperatures. In this study, the bearing power losses with water-containing gear fluids were evaluated at a specific bearing power loss test rig explicitly and compared with mineral and polyalphaolefine oils. For all investigated lubricants, a Stribeck curve behavior of the load-dependent losses is observed. The water-containing gear fluids demonstrate lower no-load bearing losses and higher load-dependent bearing losses at higher rotational speeds. The comparison of measured bearing losses with typical calculation procedures showe partially large differences. The results underline the importance of having detailed knowledge of bearing losses when evaluating gear losses in gearboxes.

Oil Churning Power Losses of a Gear Pair: Experiments and Model Validation

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
S. Seetharaman ◽  
A. Kahraman ◽  
M. D. Moorhead ◽  
T. T. Petry-Johnson
Keyword(s):  
Power Loss ◽  
Spur Gear ◽  
Companion Paper ◽  
Design Parameters ◽  
Measured Parameter ◽  
Gear Pair ◽  
Power Losses ◽  
Gear Design ◽  
Face Width ◽  
Wide Range

This paper presents the results of an experimental study on load-independent (spin) power losses of spur gear pairs operating under dip-lubricated conditions. The experiments were performed over a wide range of operating speed, temperature, oil levels, and key gear design parameters to quantify their influence on spin power losses. The measurements indicate that the static oil level, rotational speed, and face width of gears have a significant impact on spin power losses compared with other parameters such as oil temperature, gear module, and the direction of gear rotation. A physics-based gear pair spin power loss formulation that was proposed in a companion paper (Seetharaman and Kahraman, 2009, “Load-Independent Spin Power Losses of a Spur Gear Pair: Model Formulation,” ASME J. Tribol., 131, p. 022201) was used to simulate these experiments. Direct comparisons between the model predictions and measurements are provided at the end to demonstrate that the model is capable of predicting the measured spin power loss values as well as the measured parameter sensitivities reasonably well.

scholarly journals An Analytical Method to Predict Efficiency of Aircraft Gearboxes

1986 ◽  
Vol 108 (3) ◽  
pp. 424-432 ◽  
Author(s):  
N. E. Anderson ◽  
S. H. Loewenthal ◽  
J. D. Black
Keyword(s):  
Friction Coefficient ◽  
Test Data ◽  
Analytical Method ◽  
Power Loss ◽  
Large Scale ◽  
Prediction Method ◽  
Computer Programs ◽  
Spur Gear ◽  
Spur Gears ◽  
Gear Efficiency

A spur gear efficiency prediction method previously developed by the authors was extended to include power loss of planetary gearsets. A friction coefficient model was developed for MIL-L-7808 oill based on disk machine data. This, combined with the recent capability of predicting losses in spur gears of nonstandard proportions, allows the calculation of power loss for complete aircraft gearboxes that utilize spur gears. The method was applied to the T56/501 turboprop gearbox and compared with measured test data. Bearing losses were calculated with large-scale computer programs. Breakdowns of the gearbox losses point out areas for possible improvement.

An Experimental Study of Influence of Lubrication Methods on Efficiency and Contact Fatigue Life of Spur Gears

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
J. Moss ◽  
A. Kahraman ◽  
C. Wink
Keyword(s):  
Experimental Study ◽  
Power Loss ◽  
Contact Fatigue ◽  
Spur Gear ◽  
Spur Gears ◽  
Power Losses ◽  
Contact Fatigue Life ◽  
The Impact ◽  
Jet Velocities ◽  
Lubrication Conditions

An experimental investigation of spur gear behavior was conducted with the aim of quantifying the impact of lubrication methods and conditions on the power losses and contact fatigue lives. Variations of dip and jet-lubrication are defined, and these behaviors were observed as a function of the lubrication conditions. Both types of measurements were performed using the same type of back-to-back test machines and the same spur gear test articles such that their evaluations can be correlated. Power loss experiments were performed under both loaded and unloaded conditions to determine both load-independent (spin) and load-dependent (mechanical) losses. Sets of long-cycle contact fatigue experiments were performed under the same lubrication conditions to determine macropitting lives in a statistically meaningful manner. Results indicate that the spin power losses are impacted by the lubrication method significantly while the mechanical losses are not influenced. Contact fatigue lives from jet-lubricated tests are comparable to those under dip-lubricated conditions ones as long as jet velocities are sufficient.

Experimental Investigations About the Power Loss Transition Between Churning and Windage for Spur Gears

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Romain Quiban ◽  
Christophe Changenet ◽  
Yann Marchesse ◽  
Fabrice Ville
Keyword(s):  
Power Loss ◽  
Spur Gear ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Power Losses ◽  
Loss Model ◽  
Torque Measurements ◽  
Oil Immersion ◽  
Oil Jet ◽  
Very High

Abstract Oil sump lubrication is commonly used in gearboxes. When considering consistent speeds, oil immersion is usually set to low level in order to reduce associated power losses. This configuration is already used in some parts of helicopter mechanical transmissions, and it is under consideration as a lubrication solution for future electric powertrain where gearbox input speeds may be very high. The gear drag power losses are generally evaluated from either a churning power loss model for classic oil sump lubrication or a windage power loss model for oil jet lubrication. One may thus wonder how to estimate drag losses when considering a gear that only a small part is immersed. In this study, the authors investigate the transition between churning and windage phenomena for a spur gear. A series of torque measurements on a single spur gear rotating in an oil bath at numerous oil immersion levels have been carried out. Based on these results, a criterion to indicate which power loss model to use is proposed.

Performance enhancement of spur gear formed through asymmetric tooth

2019 ◽  
Vol 233 (9) ◽  
pp. 1361-1378 ◽  
Author(s):  
R Prabhu Sekar
Keyword(s):  
Wear Resistance ◽  
Performance Enhancement ◽  
Spur Gear ◽  
Spur Gears ◽  
Comparative Performance ◽  
Gear Design ◽  
Load Carrying ◽  
Gear Efficiency ◽  
Increasing Demand ◽  
The One

Tooth fracture and surface wear are the major failure causes in a gearing system. With increasing demand for high power density gear applications, the need of effective gear design becomes an important requirement to improve gear life. This article presents a method to enhance the load carrying capacity in bending and contact, as well as wear resistance to increase gear efficiency through asymmetric tooth. Asymmetric gear is the one whose pressure angles at pitch circle on drive and coast sides are different. In the present investigation, the load shared by a teeth pair, fillet and contact stresses, wear resistance, frictional power losses and the respective mechanical efficiencies have been determined for comparative performance assessment of symmetric and asymmetric spur gears.

An Experimental Study of Influence of Lubrication Methods on Efficiency and Contact Fatigue Life of Spur Gears

2017 ◽  
Author(s):  
J. Moss ◽  
A. Kahraman ◽  
C. Wink
Keyword(s):  
Power Loss ◽  
Contact Fatigue ◽  
Spur Gear ◽  
Test Machine ◽  
Spur Gears ◽  
Power Losses ◽  
Contact Fatigue Life ◽  
The Impact ◽  
Jet Velocities ◽  
Lubrication Conditions

An experimental investigation of spur gear behavior was conducted with the aim of quantifying the impact of lubrication methods and conditions on the power losses and contact fatigue lives. Variations of dip and jet-lubrication were defined and these behaviors were observed as a function of the lubrication conditions. All measurements were performed using the same back-to-back test machine and the same spur gear test articles such that all evaluations were correlated. Power loss experiments were performed under both loaded and unloaded conditions to determine both load-independent (spin) and load-dependent (mechanical) losses. Sets of long-cycle contact fatigue experiments were performed under the same lubrication conditions to determine macro-pitting lives in a statistically meaningful manner. Results indicate that the spin power losses are impacted by the lubrication method significantly while the mechanical losses are not influenced. Contact fatigue lives from jet-lubricated tests are comparable to those under dip-lubricated conditions ones as long as jet velocities are sufficient.

Load-Independent Spin Power Losses of a Spur Gear Pair: Model Formulation

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
S. Seetharaman ◽  
A. Kahraman
Keyword(s):  
Power Loss ◽  
Spur Gear ◽  
Companion Paper ◽  
Total Spin ◽  
Operating Conditions ◽  
Gear Pair ◽  
Power Losses ◽  
Gear Mesh ◽  
Drag Forces ◽  
Mechanics Model

A physics-based fluid mechanics model is proposed to predict spin power losses of gear pairs due to oil churning and windage. While the model is intended to simulate oil churning losses in dip-lubricated conditions, certain components of it apply to air windage losses as well. The total spin power loss is defined as the sum of (i) power losses associated with the interactions of individual gears with the fluid, and (ii) power losses due to pumping of the oil at the gear mesh. The power losses in the first group are modeled through individual formulations for drag forces induced by the fluid on a rotating gear body along its periphery and faces, as well as for eddies formed in the cavities between adjacent teeth. Gear mesh pumping losses will be predicted analytically as the power loss due to squeezing of the lubricant, as a consequence of volume contraction of the mesh space between mating gears as they rotate. The model is applied to a unity-ratio spur gear pair to quantify the individual contributions of each power loss component to the total spin power loss. The influence of operating conditions, gear geometry parameters, and lubricant properties on spin power loss are also quantified at the end. A companion paper (Seetharaman et al., 2009, “Oil Churning Power Losses of a Gear Pair: Experiments and Model Validation,” ASME J. Tribol., 131, p. 022202) provides comparisons to experiments for validation of the proposed model.

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