Worm Gear Gearbox

[Max Lobovsky]

I definitley do not think I could do my own calculation for teeth strength. It's far more complicated then simply shear strength for that material. There are multiple engagement points at a given time, and even just calculating the area being sheared isn't simple. I need to know this for design purposes, so I can't wait to receive the part and any info it comes with. None of the gear supplier websites I have checked list the formula.

[Andy Baker]

Originally Posted by Max Lobovsky

I definitley do not think I could do my own calculation for teeth strength. It's far more complicated then simply shear strength for that material. There are multiple engagement points at a given time, and even just calculating the area being sheared isn't simple. I need to know this for design purposes, so I can't wait to receive the part and any info it comes with. None of the gear supplier websites I have checked list the formula.

Yes you can... well, you can do some rough calculations. Stock Drive Products has a very good technical catolog section where you can follow instructions to figure gear strength (page T78). These calculations can be used as ball park figures to get you close when choosing your gear pitch.

When it comes to dynamic and shock loading, the engineering gets waaay more complicated. For our applications in FIRST robots, I suggest using the gear strength calculations linked above at the Stock Drive website. Depending on what you will be doing with your gears, you can then put in a safety factor to absorb dynamic and shock situations.

Andy B.

[Max Lobovsky]

I've read SDP's technical section and I still cannot find any information for worm gears. Even if the gear always breaks before the worm, the calculations are not comparable because the number of meshing teeth is very different and worm gears often have a sort of concave curve in the tooth to increase mesh that further changes the mechanics.