In this paper, a comprehensive methodology for calculating load sharing in multiple tooth contact is presented based on the experimental stress-optical method of caustics. The technique is applied to a set of poly-methyl-methacrylate gears at various meshing positions covering a complete meshing cycle, including single and multiple gear tooth contact. The load sharing factor (LSF) is calculated using well-established mathematical formulae from the photographs of the transmitted caustics and the obtained results are compared with the pertinent International Organisation for Standardisation and American Gear Manufacturers Association standards with which good agreement is verified. The proposed method is a reliable alternative for measuring load distribution in gear teeth compared with photoelasticity and other experimental techniques. ct Stress-optical constant

/pdf/experimental-investigation-of-load-sharing-in-multiple-gear-2asyrhu1z9.pdf

Experimental Investigation of Load Sharing in Multiple Gear Tooth Contact Using the Stress‐Optical Method of Caustics

Gears with an asymmetric involute gear tooth form were analyzed to determine their bending and contact stresses relative to symmetric involute gear tooth designs which are representative of helicopter main drive gears. Asymmetric and baseline (symmetric) toothed gear test specimens were designed, fabricated and tested to experimentally determine their single-tooth bending fatigue strength and scuffing resistance. Also, gears with an analytically optimized root fillet form were tested to determine their single-tooth bending fatigue characteristics relative to baseline specimens with a circular root fillet form. Test results demonstrated higher bending fatigue strength for both the asymmetric tooth form and optimized fillet form compared to baseline designs. Scuffing resistance was significantly increased for the asymmetric tooth form compared to a conventional symmetric involute tooth design.

Analysis and Testing of Gears with Asymmetric Involute Tooth Form and Optimized Fillet Form for Potential Application in Helicopter Main Drives

Research on lubrication characteristics of asymmetric helical gear based on CFD method

In many gear drives, the tooth load on one flank is significantly higher and is applied for longer periods of time than for the opposite one. An asymmetric tooth shape reflects this functional difference. Design intent of asymmetric gear teeth is to improve performance of the primary drive profiles at the expense of the performance off the opposite coast profiles. The coast profiles are unloaded or lightly loaded during a relatively short work period. Asymmetric tooth profiles also make it possible simultaneously to increase the contact ratio and operating pressure angle beyond the conventional gear limits. The main advantage of asymmetric gears is contact stress reduction on the drive flanks, resulting in higher torque density (load capacity per gear size). The paper presents an application of the Direct Gear Design® method to asymmetric tooth gears. This is an alternative approach to traditional design of involute gears, separating gear geometry definition from the generating (tooling) rack to maximize gear drive performance. The paper describes asymmetric tooth and gear mesh characteristics, limits of asymmetric tooth gearing, tooth geometry optimization, analytical and experimental comparison of symmetric and asymmetric tooth gears, and implementation of gears with asymmetric teeth.

http://www.akgears.com/pdf/Direct%20Gear%20Design%20for%20Asymmetric%20Tooth%20Gears.pdf

Direct Gear Design for Asymmetric Tooth Gears

Maximization of the gear transmission density presents an important task. It allows to increase the output torque within given dimensional constrains that is critical, for instance, in racing gearboxes, or to reduce size and weight of aerospace gear drives. It can also lead to reduced costs for automotive and consumer product gear trains, etc. There are several ways to increase gear drive load capacity, including advanced design, materials, and technologies. This paper presents an approach that allows optimizing gearbox kinematic arrangement and gear tooth geometry to achieve high gear transmission density. It introduces dimensionless gearbox volume functions, which can be minimized by the internal gear ratio optimization. Different gearbox arrangements are analyzed to define a minimum of the volume functions. Application of the asymmetric gear tooth profiles power density maximization is also considered.Copyright © 2011 by ASME

/pdf/gear-transmission-density-maximization-t0e14l9642.pdf

Gear Transmission Density Maximization

This paper describes the research, development of the first in the world production gearbox with asymmetric tooth profiles for the TV7-117S turboprop engine. The paper also presents numerical design data related to development this gearbox.Copyright © 2007 by ASME

Vladislav L. Dorofeyev

Papers

Application of Gears With Asymmetric Teeth in Turboprop Engine Gearbox