×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Gear speed

Gear speed

Gear speed

(OP)
Hello, I am looking for a reference as to how fast I can spin helical gears based on their size.  The only info I have found is a statement in my Mechanic Design Handbook that says if the Pitch Line Velocity goes above 2000 ft./min., cooling should be considered.  Any good sources of on this, or at least rules of thumb?

RE: Gear speed

Hi R1100S:
I guess it is good to look for some AGMA Standards. There are so many consideration issues; so, what type of application will you be doing and what speed are you seeking I think finding aswers to these questions might help you more.

Regards

RE: Gear speed


I think that is, at least partly, a heat generation (due to oil shear/churning) limit, not a structural limit.  In the past few years I witnessed/endured some painful situations resulting from real low estimates of heat generation by pretty big name gearbox suppliers houses.  Some kind of minimal lubrication system (like air-oil as used in high speed ball and roller bearings) seems to be the answer. I think I read The Nascar guys have moved to controlled lube for trans and rear axles partly for heat (thus power) reasons.

Whatcha making?

RE: Gear speed

A couple of AGMA standards that might be useful:
 917-B97 Design Manual for Parallel Shaft Fine-Pitch Gearing

 2001-C95 Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth

RE: Gear speed

2000-2500 ft./min has always been a good rule of thumb for splash systems. Actual testing above 2500 is highly recommended. The major problem with speeds above 2500 ft./min is  the speed of the gears will cut a channel in the oil bath generating excess heat caused by lack of lubrication and cooling.

gary@gearmfg.com

RE: Gear speed

(OP)
Thanks for the replies.  It looks like I am going to go with smaller gears, running below 2000 ft/min.  They are to run the balance shafts on a large single cylinder engine.  I've got plenty of engine oil flowing, so lubrication and cooling should not be a problem.

RE: Gear speed

Engine oils do not typically make very good gear lubricants, be careful!

RE: Gear speed

(OP)
Thanks for the advice Carburize, but since I already have engine oil circulating, I don't want the added complexity of another lube circut.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources