Power Transmission Gears Research Articles

Development of Plastic Gears for Power Transmission : Design on Load-Carrying Capacity

Plastic gears have various merits such as silent running, self-lubrication, and so on, but they also have some demerits such as less load-carrying capacity and unsteady life time. In our sixty-two experiments, most of the failures of plastic gears were fractures of teeth from near pitch points. On basis of these results, a new design equation for bending strength, described by the bending stress at the pitch point, is proposed. In the equation, some coefficients: tooth thickness coefficient, load increasing factor, stress correction factor, etc., are introduced to realize higher load capacity economically by making the best use of the characteristics of plastic materials.

Development of plastic gears for power transmission. Methods increasing ecomonically load-carrying capacity.

Development of plastic gears for power transmission. Methods increasing ecomonically load-carrying capacity.

Development of plastic gears for power transmission. Various methods of lengthening the life of plastic gears and their effect.

The life of plastic gears is shortened when they are used at a high temperature because they become less strong and vary in the way they mesh each other, causing them to be worn away at their root in an abnormal way. It is necessary for lengthening the life of plastic gears to take care not to generate heat in them and to keep them from rising in temperature by radiating heat quickly. The present report treats of various methods designed for lengthening the life of plastic gears having form and dimensions adapted to given operating conditions and inquiries made about whether the use of these methods can lengthening the life of plastic gears to a greater extent than anticipated at the time of designing.

Development of plastic gears for power transmission. Economical design on load-carrying capacity.

Development of plastic gears for power transmission. Economical design on load-carrying capacity.

An Optimum Design of Planetary Reduction Gear Using Rollers as Gear Teeth

It is hard to design high quality reduction gears composed of rollers as gear teeth, because the reduced rotation has irregularities inevitably. In this report, the optimum design of roller tooth gears for power transmission was investigated. According to this design, the K-H-V type planetary reduction gears of the reduction ratio of 1/15 were produced on trial. The following performances were obtained. (1) Irregularities of reduced rotation were less than 0.028 degrees. (2) Efficiency of power transmission was 80-90%. According to these results, it is possible to put this reduction gears to practical use.

A Study on the Unstable Vibration Phenomena of a Reduction Gear System, Including the Lightly Loaded Journal Bearings, for a Marine Steam Turbine

Rotatory machines such as turbines and compressors, almost invariably, include several power transmission gears. The relation between the torsional vibration and the gear transmission mechanism supported by the oil-lubricated journal bearings, however, has never been elucidated. The unstable vibration phenomena (different from ordinary phenomena such as oil whirl, oil whip and so forth) were observed in the locked train type reduction gear system of a marine steam turbine while it was subjected to running conditions with no load. The unstable vibration phenomena are assumed to be due to the self-exciting vibration system which is caused by both the oil film characteristics of the journal bearings which support the reduction gears and the torsional vibration system. The results of the calculations using a dynamic model provide a satisfactory explanation of the phenomena. According to the authors' research, the unstable vibration phenomena are strongly influenced by the torsional rigidity of the system.

Bending Fatique Strength of Gear Teeth under Random Loading : Part 1, About the Gear Tooth Pulsator and the Results of Fatique Tests under Uniformly Distributed 16 Steps Program Loading

Power transmission gears are usually used under fluctuating loads. But in the case of strength design of such gears we cannot get sufficient fatigue data and therefore the effectiveness of Miner's rule on fatigue strength is uncertain. This report deals with a new gear tooth pulsator for program and random fatigue tests and with the results of a test which was carried out under a programmed 16 steps loading. The frequencies of loads are distributed uniformly and the variation of mean load is like a saw tooth wave with positive and negative slopes. Normalized S38C and carburized SCM21 gears were tested. Every test gear had 27 teeth, 4mm module and 8mm width. Under the above condition the effects of loading sequence, changing rate and mean level of program load, gear material and heat treatment were investigated. And, though Hardrath has shown a program loading sequence effect for 7075-T6 aluminium alloy, the author's experiment indicates that its effect is not significant at the 5% level for both S38C and SCM21 gears. By arranging the cumulative damage statistically, it is concluded that Miner's theorem is not valid in the strict sense and further investigation is necessary to conclude whether Miner's rule is applicable to the fatigue design of gears.

Scoring And Its Calculation On Gears WithUngrinded Hardened Profiles

In this study, the scoring on gears with profiles hardened but not grinded, is experimentally investigated both from a quantitative and qualitative point of view. The scoring calculation on these gears is made possible by introducing a factor which is determined experimentally. INTRODUCTION The available methods of calculation of scoring on gears are only valid for cases dealing with hardened and grinded gears. On the other hand, hardened but ungrinded gears, inspite of the complaints about their working noise, are still used in industry. The reason for this study is these complaints. In this study, grinded and ungrinded gears have been observed relatively by experiments and the calculation of scoring on ungrinded gears has been made possible by the introduction of an experimentally determined factor . The physical mechanism of scoring has been covered in detail in Ref.fl ] and shall not be repeated here. Both adhesion wearing and scoring are consequences of the same physical phenomenon. The only difference is that scoring is heavier (Figure 1). Therefore both adhesion wearing and scoring will be referred to as scoring. Actually adhesion wearing prepares the necessary condition for the occurence of scoring by the high roughness it creates. EXPERIMENTS The Apparatus and Test Set up The experiments were carried out at the closed-circuit test rig given in Fig.2. The experimenting gears and the power transmission gear mechanisms are the two gear mechanisms on the stand. The torsion moment on the gears is applied by a locking Transactions on Engineering Sciences vol 2, © 1993 WIT Press, www.witpress.com, ISSN 1743-3533

Tooth Separations and Abnormal Noise on Power-Transmission Gears

Some theoretical analyses and experimental investigations are performed to give a solution to the separation of tooth meshing, which is accompanied with alarming noise or occasionally abnormal noise. Tooth separation occurs at the specific speed defined by the amount of transmission error and tangential load. The more transmission errors are or the less the supplied load is, the lower the speed, at which separation occurs, may become. The largest dynamic load and the highest sound intensity level are presented immediately after the separation occurs. Noise spectra are elucidated in comparison with tooth behaviours. It is considered that an unusual subharmonic noise would be caused by abnormal meshing of every second tooth or every third tooth.

The Effects of Materials on the Pittings of Power Transmission Gears : The Results Obtained with the Two Roller Testing Machines

The Effects of Materials on the Pittings of Power Transmission Gears : The Results Obtained with the Two Roller Testing Machines

Mine locomotives

This paper reviews the conditions and restrictions governing the use of locomotives in British coal mines, and the designs which have been evolved to meet them. The various types of locomotive are briefly described and some of the principal factors which determine the design of the locomotive are discussed.The Diesel engine, electrical equipment and power-transmission gear are considered, and particular attention is paid to braking problems and couplings.Operational experience, with a brief account of some important difficulties and the method of their solution, is included.An attempt is made to summarize the present position, to indicate the immediate problems which must be solved and to suggest further long-term lines of progress.