“ It is very hard to find out any paper regarding ‘tiger stripes’ failure, created by electrical discharge current over the gear teeth.” I wish to have some more information on this issue + how it affects the vibration / noise signatures; why does it creates the tiger stripes profile; how deep are the pittings; why does it create the noise and the possibility of running a gear with this failure?”

Has there ever been any experimental verification of the benefits of designing a gear pair to have a “hunting tooth” or is it just theoretical?

How does one select the correct size of hob/gashing cutter like hob OD, length and number of flutes for teeth cutting process based on tip circle diameter and face width of job?

We know that for cylindrical gears we have the standard DIN 3964 for defining deviations of shaft center distance and shaft position tolerances of casings. And for bevel gears? Is there some specific standard for defining deviations of center distance and shaft position tolerances of casings (orthogonal shafts), as DIN 3964 do?

What are the pros and cons of using Vickers versus Knoop hardness testers for measuring case depth in carburized gears?

A reader requests help designing the mating gear for an internal spline.

A reader asks: We are currently revising our gear standards and tolerances and a few questions with the new standard AGMA 2002-C16 have risen. Firstly, the way to calculate the tooth thickness tolerance seems to need a "manufacturing profile shift coefficient" that isn't specified in the standard; neither is another standard referred to for this coefficient. This tolerance on tooth thickness is needed later to calculate the span width as well as the pin diameter. Furthermore, there seems to be no tolerancing on the major and minor diameters of a gear.

A reader asks: I'd like to know about the different approaches and factors considered while determining the value of Ka in regards to the DIN 3990 and AGMA standards.

Question: I am a gear engineer for a motor manufacturer in China. I am writing about noise generated from cross-helical gear assembly error. I want to learn the relationship between the misalignment (center distance change and cross-angle shift) and transmission error. It is better under the loading and theory conditions. What is the trend of cross-helical gear development (use ZI worm and involute helical gear, point contact)?