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Y7

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Reply with quote  #1 
Hi
Need your help to get a reference like an article or case study to show the nature of vibration behavior and plots of varying bearing preload condition of the bearing
How will the spectrum, SCL and orbit plot will look like if preload value changes

Yousef
vogel

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Reply with quote  #2 

Google should give you plenty of results.

Bently's book has a chapter about preloads.

I also recall one article on tilting pad bearings by R. Eisenmman that helped me once.
Danny Harvey

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Reply with quote  #3 
You may need to register and/or pay but here is a link to the article that vogel referenced:

https://www.scribd.com/document/273582742/Tilting-Pad-Bearing-Preload
John from PA

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Good paper (free download) at https://oaktrust.library.tamu.edu/bitstream/handle/1969.1/163487/T23179-194.pdf?sequence=1&isAllowed=y.

Also, see https://www.kingsbury.com/pdf/Parameters%20Affecting%20PSJB%20Performance.pdf.

For some insight into journal bearings in general, see http://edge.rit.edu/edge/P14453/public/Research/2-_LEADER_-_Understanding_Journal_Bearings.pdf
Curran919

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Reply with quote  #5 
To hijack this thread, just because I've been learning more about tilting pads recently:

Does preload really refer to both the physical static shaft load, as well as the pad surface curve having a smaller radius than the shaft?
John from PA

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Quote:
Originally Posted by Curran919
To hijack this thread, just because I've been learning more about tilting pads recently:

Does preload really refer to both the physical static shaft load, as well as the pad surface curve having a smaller radius than the shaft?


In my experience "preload" refers to strictly the bearing geometry, not a force imposed by static loading.  For instance the "paid" article by Eisenmann and referenced above defines it as

Quote:
Preload is a dimensionless number describing the relationship between shaft and bearing-pad curvature, which combine to form the bearing oil wedge.
Curran919

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Reply with quote  #7 
Quote:
Originally Posted by John from PA


In my experience "preload" refers to strictly the bearing geometry, not a force imposed by static loading.  For instance the "paid" article by Eisenmann and referenced above defines it as



Indeed my Eisenmann text says exactly that. However, my colleague's handout from a BN course (and I would normally expect Eisenmann and BN to be in agreement), has a chapter on preloads which starts by defining it as:

A preload is a unidirectional steady state force acting on the rotor system.

This is categorized and further into gravitational preloads, misalignment preloads, etc. and at the end, bearing preloads, i.e. elements of bearing geometry in tilting pad bearings, pressure dam bearings and rolling element bearings. However, the type of preload in tilting pad and REB seem to me as fundamentally different. 'Preload' in a tilting pad isn't a load at all but simply has a similar effect on the stability of the fluid wedge as would introducing a physical load, right?
John from PA

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Reply with quote  #8 
Being very familiar [biggrin] with the BN training material in that instance it is referring to a force acting on the system.  But with respect to bearing design, the technical papers usually are making reference to geometry variables that cause a wedge induced preload.
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