Our expert explores standard vs. optimized gears, as well as high contact ratio gearing.

A reader is looking for the best reference materials with formulas for gear measurements over pins.

A reader wants to know how to figure out the fatigues strength, tooth root tension and other technical values of new, high-performance gear materials.

This issue's focus on bearings includes a number of important and informative articles about one of the most key components in any machine design.

Does the definition of specific sliding mean the same between ISO 21771:2007 and AGMA 917-B97? In ISO, specific sliding is the ratio of the sliding speed to the speed of a transverse profile in the direction of the tangent to the profile. In AGMA, specific sliding is ratio of gear tooth sliding velocity to its rolling velocity.

I'm not able to get a good connection between the pulley and shaft in my drive assembly. Could you explain the various ways of connecting a pulley to a shaft to prevent the pulley from slipping?

I need help determining the diametral pitch needed to achieve the closest center-to-center distance for 2 spur gears. The 1st gear is a 34-tooth and the 2nd gear is a 28-tooth. The center-to-center distance between the gears needs to be as close to 2 1/8" as possible.

I have a fairly straightforward question about a worm gear segment. But as of yet, I haven’t gotten a straight answer from any of the gear job shops I’ve approached about this job. Is there a "traditional" gear cutting method that can produce a ~180 degree enveloping worm gear segment when a feature on the back of the part will interfere with a complete rotation of the part? Or am I left with only the option of 4- or 5-axis surfacing with a CNC mill? I have presented this part to several well-known gear shops in the U.S. without a straight answer on how the part can be made. Any help you could offer would be appreciated.

Referencing a June 2014 Article, “High Gear Ratio Epicyclic Drives Analysis,” by Dr. Alex Kapelevich: I have designed a small compound epicyclic gearbox with common planets. Sun = 10 teeth Planet = 14 teeth Ring Gear stationary = 38 teeth Ring gear output = 41 teeth profile shifted onto a 38 tooth pitch diameter. Carriers are simply cages for the planet alignment and location. According to your article, and according to my calculations and the prototype I have built, my inputto- output ratio is a reduction of 65.6:1. I am using a ~ VG1 viscosity grease and Nylatron materials for the gears and carriers.

Questions by readers answered by Experts in the field.