Spur Gear - addedum modification/profile shift coefficient
Spur Gear - addedum modification/profile shift coefficient
(OP)
Hi all,
If this is a repeated post, i'm sorry, but from my searches here in the fórum i couldn't find na answer to my doubt.
Just joined the forum (I'm an electrical engineer, so i don't have much experience in mechanical design) and the reason was because after reading more than 5 books about gears i couldn't find a proper answer (some are handbook of gear design and Shigley's Mechanical engineering design, and many more).
So, i need to design a gearbox of 5 stages, but my question will only be about one stage, because when i solve this i can do the rest.
Stage: 13 teeth pinion, 33 teeth gear, alpha = 20º
Of course there will be interference and from the books i read, to remove this interference the addendum modification coefficient is equal to x = (Zmin - Z)/Zmin, being Zmin = 2/sin(alpha)^2
According to the books, if Z1 + Z2 > 2* Zmin, then pinion's addendum = 1+ x and gear's addendum = 1-x. Else, if Z1 + Z2 < 2*Zmin, we need to do a shifting with center distance modification.
Accordingly to this equations, in my case the value of x would be 0.24. One exemple that i saw, would give to my x the value of 0.39. Now my question, is there any other formula, perhaps a better one (since this value was given by a program)?
Grateful
If this is a repeated post, i'm sorry, but from my searches here in the fórum i couldn't find na answer to my doubt.
Just joined the forum (I'm an electrical engineer, so i don't have much experience in mechanical design) and the reason was because after reading more than 5 books about gears i couldn't find a proper answer (some are handbook of gear design and Shigley's Mechanical engineering design, and many more).
So, i need to design a gearbox of 5 stages, but my question will only be about one stage, because when i solve this i can do the rest.
Stage: 13 teeth pinion, 33 teeth gear, alpha = 20º
Of course there will be interference and from the books i read, to remove this interference the addendum modification coefficient is equal to x = (Zmin - Z)/Zmin, being Zmin = 2/sin(alpha)^2
According to the books, if Z1 + Z2 > 2* Zmin, then pinion's addendum = 1+ x and gear's addendum = 1-x. Else, if Z1 + Z2 < 2*Zmin, we need to do a shifting with center distance modification.
Accordingly to this equations, in my case the value of x would be 0.24. One exemple that i saw, would give to my x the value of 0.39. Now my question, is there any other formula, perhaps a better one (since this value was given by a program)?
Grateful





RE: Spur Gear - addedum modification/profile shift coefficient
I don't know what rationale you used for selecting a 13T/33T combination, but you might consider a combination using greater numbers of smaller size teeth with a similar ratio. A spur pinion with at least 19T would perform much better.
RE: Spur Gear - addedum modification/profile shift coefficient
RE: Spur Gear - addedum modification/profile shift coefficient
israelkk, like you said, you don't learn by books (but in this case i don't think your exemple will work, since all mechanical design is theorical and not pratical ;), you can construct a car without knowing nothing and just with a piece of wood and hammer - being practical), so, i'm trying to make a practical exemple - i will construct the gears and test their efficiency and durability, so i can improve in this field.
Any more help would be appreciate
Best regards
RE: Spur Gear - addedum modification/profile shift coefficient
RE: Spur Gear - addedum modification/profile shift coefficient
Like you said in your reply, i'm not an experienced mechanical engineer, and i told that in my post, the initial one. About not making the right questions or not knowing how to make the question, don't know another way to make it (from the terms i learned from the books), maybe "How to determine the profile shifting/ addedum modification coefficient (to maximize sliding and remove interference)?"
Best regards
RE: Spur Gear - addedum modification/profile shift coefficient
Start with AGMA 913-A98. And good luck to you.
RE: Spur Gear - addedum modification/profile shift coefficient
RE: Spur Gear - addedum modification/profile shift coefficient
The relevant AGMA standards you will need are AGMA 1003-H07 , AGMA 913-A98 , AGMA 901-A92 .
Since you noted that space is a concern with your gear drive design, I'd recommend starting with AGMA 901-A92 "A Rational Procedure for the Preliminary Design of Minimum Volume Gears".
Good luck with your project.
Terry
RE: Spur Gear - addedum modification/profile shift coefficient