AGMA Modified Addendum Design

[jbh73]

Hi,

I'm working on a gear train design that requires addendum modification for several of the pinions and gears. I'm using ANSI/AGMA 1003-G93 as a guideline. I like to understand where table values I use in my designs come from, so I've created a spreadsheet that calculates the enlarged spur pinion and reduced spur gear table values (Tables 4 and 5 in the standard) using the given equations. My problem is that the equation and table values do not match. The equations match the Table 4 values for pinions with 13-23 teeth, but not for smaller numbers - the fact that these sections of the table are separate makes me think this is not a coincidence. Also, the formulas don't match any of the values for Table 5. I've found several errors in the formulas, so it wouldn't surprise me if there were more. Does anyone know why the formula and table values are different? I'd guess they've been modified based on experience, but I'd still like to know where the table values come from. Thanks!

 

[diamondjim]

The smaller tooth pinions are undercut
and require special layouts to
determine the y factors.
These are determined by layout and not
by experience. It also is dependent
whether they are hobbed or shaped as
to the amount of undercutting.