Challenge of week-Need to design and develop a gearbox with 0 or 1mr back lash

I'm with Del on this one. Spring-preloaded anti-backlash gears work well for low-powered applications, but again; how much horsepower do you need to transmit and what is the magnitude, position, and frequency of the shock load(s)?

One can also use split anti-backlash gears that are periodically adjusted for wear. These work well, but can be sensitive when large pitch diameters are combined with large temperature changes.

A couple of questions here: Why is it so important to eliminate backlash in your design? Is the inherit accuracy of the gears (say A.G.M.A. classification) important as well? Surely it must be, as it sounds as it positioning accuracy is critical and the load occassionally places reverse stress on the gear teeth.

I bring this up because a bit of backlash is usually the least important thing in good gear design, save for special low-speed applications where position accuracy is most critical and must be repeatable. Usually, the most important thing about a gear is its composite accuracy; i.e. the combination of pitch line runout, flutter, and tooth index errors. And a bit of backlash is necessary to allow the pitch circles to "grow" as the gears become warmer, allow a bit more lubricant to enter the mesh, and make up for small errors in the centre distances of mating gears.

Best Regards,

Ing. Robert Forbus

Sir:

Odd that you would come into a problem we solved years ago...not actually for backlash prevention but for high ratio reduction. We found very very low backlash....better than any gear box we could find at that time...30+ years ago.

Gasoline 2 cycle engine input ..up to 40 HP....max 7000 RPM...inheretly high pulsation of input power from two cycle........ secondary output not to exceed 650 RPM.

Accomplished with rubber toothed 8 mm timing belts...very precise shaft centers ...two step system.....before they made Kevlar belts....shaft centers just far enough apart for mechanical clearance of pulleys....very compact.

Youdid not indicate the parameters of your HP and ratio needs.

Today you could handle about double that HP input with Kevlar...

MR. GUY