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September/October 1986

Archive > 1986 > September/October 1986

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Feature Articles

Tooth Strength Study of Spur Planet Gears
In the design of any new gear drive, the performance of previous similar designs is very carefully considered. In the course of evaluating one such new design, the authors were faced with the task of comparing it with two similar existing systems, both of which were operating quite successfully. A problem arose, however, when it was realized that the bending stress levels of the two baselines differed substantially. In order to investigate these differences and realistically compare them to the proposed new design, a three-dimensional finite-element method (FEM) approach was applied to all three gears.

Technical Articles

Gears for Nonparallel Shafts
Transmission of power between nonparallel shafts is inherently more difficult than transmission between parallel shafts, but is justified when it saves space and results in more compact, more balanced designs. Where axial space is limited compared to radial space, angular drives are preferred despite their higher initial cost. For this reason, angular gear motors and worm gear drives are used extensively in preference to parallel shaft drives, particularly where couplings, brakes, and adjustable mountings add to the axial space problem of parallel shaft speed reducers.

Improved Gear Life Through Controlled Shot Peening
The search for greater gear life involves improvement in cost, weight and increased power output. There are many events that affect gear life, and this paper addresses those relating to fatigue, gear tooth pitting, fatigue strength losses due to the heat treating processes and shot peening technique. The capability of shot peening to increase fatigue strength and surface fatigue life eliminate machine marks which cause stress risers, and to aid in lubrication when properly controlled, suggests increased use and acceptance of the process.

Practical Analysis of Highly-Loaded Gears by Using the Modified-Scoring Index Calculation Method
The power of high speed gears for use in the petrochemical industry and power stations is always increasing. Today gears with ratings of up to 70,000kW are already in service. For such gears, the failure mode of scoring can become the limiting constraint. The validity of an analytical method to predict scoring resistance is, therefore, becoming increasingly important.

Pressure Angle Changes in the Transverse Plane for Circular Cut Spiral Bevel Gears
Recently it has been suggested that the transverse plane may be very useful in studying the kinematics and dynamics of spiral bevel gears. The transverse plane is perpendicular to the pitch and axial planes as shown in Fig. 1. Buckingham has suggested that a spiral bevel gear may be viewed as a limited form of a "stepped" straight-tooth gear as in Fig. 2. The transverse plane is customarily used in the study of straight toothed bevel gears.

Departments

Editorial (Publishers Page)
"It's show time!" Ready or not, on Sept 3, the biennial International Machine Tool Show opens at McCormick Place, Chicago. Planning a show that encompasses displays from over 1000 companies from 29 nations and an associated technical conference presenting more than 200 papers on 50 topics has not been without its problems.

Long on High Technology -- Short on High Technologists (Voices)
At the present time, technology seems to be moving faster than our ability to educate people in its utilization. this is particularly true of the manufacturing engineering profession.

Technical Calendar (Events)
The complete technical calendar from the September/October 1986 issue of Gear Technology.