Worm/Wormgear Reference Circle Diameter--definition? 2

[TimtheToolMan]

What is the "reference circle diameter" of worm (df) and same for wormgear?

I am using Machinery's Handbook rev 22 to calculate strength of worm gearing and Df and df (f is subscript) are used in calculation and does not define these variables.

 

[israelkk]

It is the worm and gear pitch diameters. You can see it in the catalog of HPC gears catalog

http://www.hpcgears.com/newpdf/technical_pdfs/c27798-810technicalgearing.pdf

See page 10 of this file. You can see they use the D (pitch diameter power 1.8 as Df power 1.8 in Machinery's Handbook 22th edition.

I had the same problem few years ago.

By the way the 22th edition was the last that refers to worm gears. It seems that the Macinery's Handbook committee doesn't see it as an important issue any more. This also prove that new edition is not always better. Personally I have 22th, 23rd, 24th

 

[TimtheToolMan]

israelkk,

You not only answered the questions but made me aware that older handbooks are worth keeping.

Thanks!
Tim