Gears are currently run at high speed and under high load. It is a significant problem to develop lubricants and gears with high load-carrying capacity against scoring. The particles of molybdenum disulfide have been considered to increase the scoring resistance of the gears. The wear characteristics and the scoring resistance of the gears lubricated with MoS2 paste and MoS2 powder have been investigated. (1) However, there are few investigations on the performance of the gears coated with MoS2 film with respect to scoring.
The most conclusive test of bevel and hypoid gears is their operation under normal running conditions in their final mountings. Testing not only maintains quality and uniformity during manufacture, but also determines if the gears will be satisfactory for their intended applications.
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.
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.