pressure angle
pressure angle
(OP)
Would anybody tell me the differences of gear performance at 20 deg pressure angle vs. 14.5 deg pressure angle?
Thanks,
Ramesh
Thanks,
Ramesh
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RE: pressure angle
2. 20 deg. gears require a closer tolerance on the gear-to-gear center distance to obtain the same backlash as 14-1/2 deg. gears.
These are the two basic rules. So if you need small gears without undercutting the teeth, you need a larger pressure angle. If you have relatively large gears with lots of teeth you'd probably like to use a smaller pressure angle since it will be a little more difficult to hold tolerances on the larger center distance and still minimize backlash.
Don
Kansas City
RE: pressure angle
Thanks for your response. Our gears have 48 or more teeth. What I am wondering about the noise level at 20 deg vs. 14-1/2 deg. We are wondering about changing the pressure angle to 20 deg from present 14-1/2 deg. If noise is not going to be an issue, we would like to try 20 deg PA gears.
Thanks
Ramesh
RE: pressure angle
Don
Kansas City
RE: pressure angle
20 is the industry standard, 14.5 may cost more or be harder to get.
RE: pressure angle
RE: pressure angle
14 1/2 degree PAs will have:
Higher contact ratio
Lower Bending Strength
Higher Shear Strength
More undercut
Lower bearing stresses and separation loads
20 degree PA will have:
Lower contact ratios
Higher Bending Strenth
Lower Shear Strenght
Less Undercut
Higher Bearing stress and separation loads
Most people are worried about Bending Strength in their designs - hence use 20 deg PA as a starting point.
Where are 14 1/2 deg PA an advantage?
- worm drives where the primary failure mode is augering of the worm thru the gear - esp if the gear is plastic
- designs that are challenging to achieve a contact ratio of greater than 1
- designs where bearing life is marginal
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