The development of a new gear strength computer program based upon the finite element method, provides a better way to calculate stresses in bevel and hypoid gear teeth. The program incorporates tooth surface geometry and axle deflection data to establish a direct relationship between fillet bending stress, subsurface shear stress,
and applied gear torque. Using existing software links to other gear analysis programs allows the gear engineer to evaluate the strength performance of existing and new gear designs as a function of tooth contact pattern shape, position and axle deflection characteristics. This approach provides a better understanding of how gears react under load to subtle changes in the appearance of the no load tooth
contact pattern.
In the field of large power transmission gear units for heavy machine industry, the following two development trends have
been highly influential: use of case hardened gears and a branching of the power flow through two or more ways.
The effect of various lubricant factors on wormgear efficiency has been evaluated using a variety of gear types and conditions. In particular, the significant efficiency improvements
afforded by certain types of synthetic
lubricants have been investigated to determine the cause of these improvements. This paper describes broad wormgear testing, both in the
laboratory and in service, and describes the extent to which efficiency can be affected by
changes in the lubricant; the effects of viscosity, viscosity index improvers and, finally, synthetic lubricants are discussed. The work concludes that lubricant tractional properties
can play a significant role in determining gear efficiency characteristics.
Material losses and long production times are two areas of conventional spur and helical gear manufacturing in which improvements can be made. Metalforming processes have been considered for manufacturing spur and helical gears, but these are costly due to the development times necessary for each new part design. Through a project funded by the U.S. Army Tank - Automotive Command, Battelle's Columbus
Division has developed a technique for designing spur and helical gear forging and extrusion dies using computer aided
techniques.
Gear research seems to be thriving. Between September 10th and October 17th, 120 papers about gears
were presented at three conferences in Milwaukee, Boston, and Washington, to a total audience of about 400. The authors were from nine countries. Slightly more than half of the papers were prepared by authors who
live outside the US and Canada.
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