bearing preload design

[steve5000]

Hi, Can any suggest a good website and book to help me in desinging how to preload bearings in the correct way, and calculating the preload of bearings. the application that I have is two bearings 17 i/d, 26 o/d with a rotating shaft going at 3000rpm.

 

[tito662]

Well ive worked on preloaded bearings..
I advice u to look at the publication of Amasorain for the calculation of the contact angle in a preloaded bearing..

 

[Heckler]

Here is a good website

http://www.tec.nsk.com/Handbook.asp?menu=8,0,0,0&PageID=/Preload/Preload.html

Heckler
Sr. Mechanical Engineer
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(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

 

[Tmoose]

If these are preloaded ball or roller bearings I'd get familiar with the info provided by the bearing manufacturer, and check with their tech support after I had become familiar with the terminology and standard practices, based on speed, load, stiffness requirements, blah-blah-blah.

Preload in journal bearings means something quite different, according to Kingsbury.

http://www.kingsbury.com/pdfs/universe_brochure.pdf

 

[rmw]

How are you going to set this preload? Spacers? Turn of the nut or what?

rmw

 

[steve5000]

The way I am planning to preload these bearing is to shrink fit one of the bearing to the shaft, clamp the two outer race together with a spacer and clamp on top and have a spring inside to put preload on the inner race as one inner race is free to move. The bearing I am using SKF, there catalogue has lots of information but not the best way of preloading bearings what I can see. so i was hoping someone would have a good website or book to expalin about preloading bearing and calculations on bearing. thanks

 

[volpegrigia]

These are a couple of books that delve into the subject of bearing design, analysis and application, including preload.

Brandlein - Ball and Roller Bearings: Theory, Design and Application - Wiley
Harris - Rolling bearing analysis - Wiley

I hope this helps.

 

[israelkk]

The best and only way to get an accurate and known preload is to order the two bearing as a duplex pair. The manufacture grinds the bearing races such that when the outer races and the inner races are clamped and touch each other respectively the correct preload achieved.

 

[Tmoose]

Spring preloaded ball bearings (angular contact or deep groove/conrad, etc) bearings do not rely on spacer length to establish preload value. The spring force determines that. But the preload force must be applied uniformly, and the radial load must not be great enough to overcome the spring preload. Plenty of electric motors use readily available ball bearings, axially clamp one, and pop one of these springs next to the other bearing that has axial clearance and the OD is a slip fit in its housing.

http://www.bardenpressoffice.co.uk/portals/46/24_fig1.jpg

http://www.smalley.com/images/photos/springs_app_bearing.jpg

A rotating shaft will generally NOT have freely moving races (slip fit), as race creep will result in shaft and race wear.
The motion is much like a hula-hoop, always in contact my belly. Imagine

http://www.mgb-home.de/hula-hoop.jpg

Actually it is more like an internal gear with friction replacing the gear teeth, and the inner "gear" (shaft) just 0.001 inch smaller than the ouer gear (race)

http://www.fi.edu/time/Journey/Time/Escapements/internalgear.gif

Special loading conditions can change this rule to prevent race creep. Compare your application to Table 7.1 here -

http://www.ntnamerica.com/pdf/2200/brgfits.pdf