Anyone involved in the design, manufacture and use of gears is concerned with three general characteristics relative to their application: noise, accuracy, and strength or surface durability. In the article, we will be dealing with probably the most aggravating of the group, gear noise.
It has previously been demonstrated that one gear of an interchangeable series will rotate with another gear of the same series with proper tooth action. It is, therefore, evident that a tooth curve driven in unison with a mating blank, will "generate" in the latter the proper tooth curve to mesh with itself.
Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of the gear teeth. Its purpose is to correct errors in index,
helical angle, tooth profile and eccentricity. The process can also improve tooth surface finish and eliminate, by crowned tooth forms, the danger of tooth end load concentrations
in service. Shaving provides for form modifications that reduce gear noise. These modifications can also increase
the gear's load carrying capacity, its factor of safety and its service life.
On gear drives running with pitch line velocities below 0.5 m/s so called slow speed wear is often observed. To solve
some problems, extensive laboratory test work was started 10 years ago. A total of circ. 300,000 h running time on FZG back-to-back test rigs have been run in this speed range.
Your May/June issue contains a
letter from Edward Ubert of Rockwell
International with some serious questions
about specifying and measuring tooth thickness.
Much of the information in this article
has been extracted from an AGMA
Technical Paper, "What Single Flank
Testing Can Do For You", presented in
1984 by the author
In response to Ed Uberts letter, we have come a long way in gearing since WWII. The Europeans do use long
addendum pinions in many cases. This modification does improve load capacity, sliding conditions and the working life of a gearset. When modifying a pinion tooth it is
necessary to modify the gear tooth or adjust the center distance accordingly but we will leave that to the designers.
This letter is in response to your article
asking the readers where their interests
lie. The division of Rockwell International where I work has engineering departments in Cicero.
Much information has been written on gear inspection, analytical. functional. semiautomatic and automatic. In most
cases, the charts, (if you are lucky enough to have recording
equipment) have been explained.