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Lewis Y factor calculations

Lewis Y factor calculations

Lewis Y factor calculations

(OP)
Hello,

I've been looking for a practical way to determine the Lewis form factors "Y" for gears.  This factor is defined as Y=(t^2 x Dp)/6l, where t= tooth thickness at critical bending stress points, DP= diametral pitch, l= tooth length as measured from t to top of gear tooth.  Reputable gear literature suggests that to find t and l, to inscribe the gear tooth profile with a parabola, sometimes refered to as the stress parabola or Lewis parabola, tangent to the fillet radius. "t" is then found by measuring or calculating the distance across the tangency points. This is not as easy as it sounds, even with CAD or Solidmodeling software.

I have seen Y factors listed in books written by Buckingham and also in the AGMA information sheet 908-B89, however I would like to find a mathematical formula that I could put into an spreadsheet or into code.

Any suggestions?????


RE: Lewis Y factor calculations

Y=2/3 times X
Some agma computer calculations
show the X and t values that are
used to calculate the AGMA Y and J
factors.  This AGMA Y factor is not
the  same as the Lewis Y factor but
if computer output shows the X value,
the above formula applies.
AGMA did show how to calculate the
Lewis Y factor at the tip and also
at the highest point of contact in
their earlier manuals.

RE: Lewis Y factor calculations

I believe the web address should not have the "1" after  www.

It looks like UTS has changed their site and I could not find anything when searching for berg or lewis.

RE: Lewis Y factor calculations

Everything you need to make a Lewis factor spreadsheet is in AGMA 908-B89, though it is not particularly easy.  You have to do some iteration, which can be done in a spreadsheet.

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