×
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

Bearing spin on shaft

Bearing spin on shaft

Bearing spin on shaft

(OP)
Gentlemen,
My background is Electrical Engineering, so excuse me if I don't use the correct terminology.

We use several helical gearboxes at our plant. They are parallel shaft, single reduction units. Each shaft is approx. 6 inches in diameter. Input shaft speed is 1800 RPM. Each shaft is support by tapered roller bearings. Lubrication is spray oil mist, and there is a heat exchanger and filter in the lubrication system piping.

When the boxes are rebuilt (approx. 5 years of service time), there are signs of bearing spin on the shaft but no signs of bearing spin in the housing. The shaft-to-bearing fit has been tightened from m6 to n6 in an effort to resolve the problem. We will not know the results until the box is rebuilt again. In the meanwhile, are there other things that we should be checking?
Thanks,
Raisinbran

RE: Bearing spin on shaft

First thing coming to mind would be to check the alphas of the shaft and the bearing materials. Make sure the bearing isn't growing too much at higher temps.

RE: Bearing spin on shaft

Were these gear boxes designed by your company or purchased units?  If they were designed by your company the RE should have done a tolerance analysis before parts were made.  If this was a purchased unit I would contact the manufacture.

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 3.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
      o
  _`\(,_
(_)/ (_)

(In reference to David Beckham) "He can't kick with his left foot, he can't tackle, he can't head the ball and he doesn't score many goals. Apart from that, he's all right."  -- George Best

RE: Bearing spin on shaft


These guys say an m6 shaft should be approximately +0.0005/+0.0015 inch. http://www.roymech.co.uk/Useful_Tables/ISO_Tolerances/ISO_286_2s.html

These guys say their bearing bores are -0.0000/+0.0010 inch.

If all the parts WERE in spec it could have gone together with 0.0005 inc clearance, or maybe 0.0005 inch interference.

With the new n6 fit the shaft should be about +.0010/+0.0020, so it might still be line-to-line, if the bearing bores were at maximum (not likely, but....).
I'd probably confirm the new fit.  There should have been codes on the bearings indicating actual bore size.

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