Talk:Plain bearing/Archives/2013

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Proposed merge from journal bearing

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result was merge. Wizard191 (talk) 17:34, 9 February 2010 (UTC)

A journal bearing is ~~just another name for~~ a subset type of plain bearing as supported by: [2], [3], [4], [5], [6] and [7]. As such, I propose that the two are merged. Wizard191 (talk) 01:39, 30 December 2009 (UTC)

Oppose Page 1 of your first book actually specifically states that a journal bearing is a specific type of plain bearing: journal bearings have the force acting at a right angle to the axis, while a thrust bearing has the force acting in parallel. Source #6, starting at the bottom of page 99, says the same thing; another (page 557, at "3." under section "Infinitely Long Journal Bearings") uses this terminology in passing. This subset of plain bearings would have design and application differences from thrust bearings. 76.253.140.190 (talk) 07:45, 31 December 2009 (UTC)

I just noticed that the "Design" section of Plain bearing has that description, though the wikilink to thrust wasn't there. 76.253.140.190 (talk) 07:48, 31 December 2009 (UTC)

You are quite right, it is a subset type of plain bearing; I was in a rush at the time when I first wrote this so I apologize for that. However, I don't see this as a reason to not merge the two because this article already addresses the same topics that journal bearing does, therefore the journal bearing article is just redundant. Wizard191 (talk) 15:11, 31 December 2009 (UTC)

what advantage do you see from the merge? the normal way to handle this would be to move the journal brg stuff to the journal brg article, and then use this as a pointer to that article, and then have a separate section here about thrust bearings etc. Greglocock (talk) 06:39, 1 January 2010 (UTC)

The point is not to split up the information, but to combine it. Whether the plain bearing is a thrust bearing or a journal bearing the principles under which the bearing acts are the same. The only difference is the shape and the type of applied load. I don't want to write two mechanics and lubrication sections for two independent articles when there's no logical reason to separate them. Wizard191 (talk) 04:20, 4 January 2010 (UTC)

Well that is certainly a reasonable argument. Greglocock (talk) 05:16, 4 January 2010 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Lost info

All references to North American usage were lost. Peter Horn User talk 13:17, 25 April 2010 (UTC)

A journal bearing, sometimes referred to as a friction bearing, is a simple bearing in which a shaft, or "journal", or crankshaft rotates in the bearing with a layer of oil or grease separating the two parts through fluid dynamic effects. The shaft and bearing are generally both simple polished cylinders with lubricant filling the gap. Rather than the lubricant just "reducing friction" between the surfaces, letting one slide more easily against the other, the lubricant is thick enough that, once rotating, the surfaces do not come in contact at all. If oil is used, it is generally fed into a hole in the bearing under pressure, as is done for the most heavily-loaded bearings (main, connecting rod big-end and camshaft) in an automobile engine. A simple oil "slinger" in the sump and an appropriate feed hole in the bearing shell are considered adequate for small single-cylinder engines, such as those used in lawnmowers.

The casing that houses the journal bearing is called the journal box or axle box.^{[citation needed]}

journal box or axle box are common N. AM. usage, see locomotive etc. Peter Horn User talk 13:17, 25 April 2010 (UTC)

For journal bearing see Glossary of rail terminology#J Peter Horn User talk 15:46, 25 April 2010 (UTC)

Types

Liquid journal bearings can be hydrodynamically lubricated or hydrostatically lubricated. The difference between hydrostatic and hydrodynamic forces is in the way the pressure that supports the bearing is initially and subsequently maintained.

Hydrostatic bearings

In a hydrostatic bearing, the pressure is always present at a value that is desirable and is achieved by an external pump which forces lubricant into the system. The pump provides a magnitude of pressure that aims to supplement the pressure which is created by the bearings rotation, if any. In a hydrodynamic bearing the pressure in the oil film is maintained by the rotation of the shaft itself.

Hydrodynamic bearings

Hydrodynamic bearings require greater care in design and operation than hydrostatic bearings. They are also more prone to initial wear because lubrication does not occur until there is rotation of the shaft. At low rotational speeds the lubrication may not attain complete separation between shaft and bushing. As a result, hydrodynamic bearings are often aided by secondary bearings which support the shaft during start and stop periods, protecting the fine tolerance machined surfaces of the journal bearing.

Please substantiate the statement that 'Hydrodynamic brgs are often aided by secondary bearings...' As a rotating equip engineer in the metals, petrocemicals & oil and gas sectors with >25 yrs experience I've never come across a turbomachine with backup bearings. Is this for a specific application? --Andy mellor (talk) 18:14, 3 March 2013 (UTC)Andy_Mellor

General theory

A journal bearing works on the principle that, over an infinitesimally small length of the shaft circumference, the theory of a lubricated pair can be applied. The convergence as well as the viscosity and velocity of fluid generate a pressure film. As one surface moves, it drags oil into the gap that is made between it and the other. As the oil moves forward, the space decreases. The oil can be considered to be incompressible enough to generate pressure. This pressure prevents oil from entering the gap created. The oil within the gap reaches a pressure limit after which it pushes oil through the smaller space.

Journal bearing link

I'm not sure that the journal bearing link in the image caption is such a good idea, because it makes it appear that there is another article about journal bearings, but there isn't. The journal bearings used on locomotives are of the same design as any other journal bearing discussed in this article. Wizard191 (talk) 17:24, 27 April 2010 (UTC)

I am talking about the journal bearings on the freight car trucks. The trucks on the tenders of locos had the same bearings. CAR and LOCOMOTIVE CYCLOPEDIA^[1] (1970), DICTIONARY OF CAR AND LOCOMOTIVE TERMS, A SIMMONS-BOARDMAN PUBLICATION (hard copy). This, of course, is totally obsolete, yet of historical interest. Peter Horn User talk 17:54, 27 April 2010 (UTC)

I'm quite confused now. Are you saying that the journal bearing on the freight car truck is different than all other journal bearings? Wizard191 (talk) 18:25, 27 April 2010 (UTC)

No, not really. I just looked into my 1970 edition of the C and L Cyclopedia for the section of the box with the axle. No luck, as it only showed sections of the box that showed how to convert the box so as to accept RR roller bearings or RR ball bearings. The journal box is some what like a stuffing box and as such could be described (treated) as as section of that article. To get a good section of that box and axle I would have to find an edition older than 1970. May be I could find it at the Canadian Railway Museum. Anyway, it is 15:12 here and I have to leave this until at least tomorrow. Cheers. Peter Horn User talk 19:17, 27 April 2010 (UTC)

Railway (but not locomotive) bearings are quite different. Firstly, they carry a heavy load that's always in one direction downwards. Most of them are only half a bearing on the outer shell. They just don't need to worry about forces the other way, or even the axle "jumping out" of the bearing. A few large two-stroke engines had a similar arrangement with a "slipper bearing", but even those weren't to the same extent. Secondly, they were a high-technology bearing for their day, running at high speeds and high loads, but without any attendant or engine tender. Although we think of walking an entire train feeling for a hot box with the back of your hand as labour intensive, a similar bearing in a stationary engine at that time would have a driver (or at least a boy) watching it continually. Railway bearings ran for hundreds of miles with hardly a stop, let alone attention. Andy Dingley (talk) 19:53, 27 April 2010 (UTC)

I found what I wanted & needed on pp 834 & 835 of my C and L Cyclopedia. Peter Horn User talk 20:00, 27 April 2010 (UTC)

Andy thanks for the full description, because I was unaware of that design. Could you incorporate that into the article at all? Peter, any image(s) would be greatly appreciated. Wizard191 (talk) 20:01, 27 April 2010 (UTC)

To photo copy p. 834 and scan the copy is no rocket science, but it is time consuming. The worst thing is that our Brother printer/scanner/fax is out of ink & therefore temporarely out of commission. Peter Horn User talk 20:09, 27 April 2010 (UTC)

This morning I attempted to scan those two pages of the Cyclopedia directly into my CP file but I encountered a snag. I have to find the Brother installation disk and reinstall the program. That will take some time. In addition I need instruction as to how to transfer the images from my CP to Wiki. As an alternative I could E-mail them to Wizard as attachments and let him do that job. I have not forgotten about this and I'll keep you guys posted. Peter Horn User talk 15:24, 28 April 2010 (UTC)

I have no problem reformatting the images and posting them to the commons. You can just used the "email this user" button on my talk page when you are ready to email them to me. Thanks for all the help! Wizard191 (talk) 18:03, 28 April 2010 (UTC)

Peter, any luck with that scanner? Wizard191 (talk) 00:51, 4 May 2010 (UTC)

Peter Horn User talk 19:32, 22 May 2010 (UTC)

Peter Horn User talk 16:11, 18 May 2010 (UTC)

Wizard, our scanner is not yet up and runnig, but I found an image in bogie. Peter Horn User talk 01:10, 18 May 2010 (UTC) Peter Horn User talk 01:19, 18 May 2010 (UTC)

See also Hot box for additional info. Peter Horn User talk 01:34, 18 May 2010 (UTC)

Awesome! That's much clearer to me. Do we still need the photograph then? Wizard191 (talk) 12:32, 18 May 2010 (UTC)

The X section would still be useful. My daughter promised to reprogram the PC tonight so as to enable the use of the scanner cum copier cum fax machine. In my opinion, the journal box is a kind of stuffing box and as such could be described as a section of that article. What do you think? Peter Horn User talk 13:48, 18 May 2010 (UTC)

I'm not familiar with stuffing boxes, but from my meager understanding it seems that a journal box is two things: a journal bearing and a stuffing box. As such it seems that it should be described independently of a stuffing box. Wizard191 (talk) 17:45, 18 May 2010 (UTC)

That basically would mean undoing the merger. Peter Horn User talk 00:41, 21 May 2010 (UTC)

Or make journal box an article in it's own right. Peter Horn User talk 00:45, 21 May 2010 (UTC)

I'd say start an article at journal box and see where it goes. Wizard191 (talk) 12:25, 21 May 2010 (UTC)

In that scope, I'd be more inclined towards "history of railway axleboxes" (with a snappy article title). Unless US practice is to use "journal box" where a Brit would use "axlebox" for the very specific meaning of railway axleboxes, I can't see journal box, in the broad sense of meaning "the housing for a plain journal bearing", as being a good scope for an article. Railway axleboxes, in their narrow context, have a good scope. There's a historical evolution from cart wheels, through grease axleboxes, oil axleboxes and finally roller bearings. There's also a good commercial context to tie this technology into: better and more reliable bearings encouraging faster trains, heavier trains, and heavier individual wagons that in turn encouraged mechanical loading & unloading. Andy Dingley (talk) 12:50, 21 May 2010 (UTC)

Andy, that sounds like the best idea yet! Wizard191 (talk) 12:59, 21 May 2010 (UTC)

Yet the word "journal box" is part of the historical usage of the North American, including Canadian usage. See illustration above. I'll get the scan of the X section yet. Peter Horn User talk 13:36, 21 May 2010 (UTC)

Make that "Figure 8-8. US Government document" as shown above. Peter Horn User talk 13:40, 21 May 2010 (UTC)

I'd still prefer "axle box" (with redirs either way). Seems clearer for an American to read "axle" than a Brit to read "journal". Journal also has a much wider use for bearings in general. Andy Dingley (talk) 14:42, 21 May 2010 (UTC)

In that case "journal box" will redirect to "axle box" and the first paragraph will mention both terms as British and North American respectively. What else is new. By the way, does Andy have an illustration (image) of the British version? Peter Horn User talk 15:23, 21 May 2010 (UTC)

I don't have sectioned images to hand, might have some on the shelves, but probably don't have any that are old enough to meet Commons constraints. I could try and take some external photos (if I don't already have them), but those aren't particularly illustrative: a box is a box is a box. Andy Dingley (talk) 15:27, 21 May 2010 (UTC)

Not quite, see below. Peter Horn User talk 16:05, 10 June 2010 (UTC)

If you happen to have a museum close by, take a photo of any bogie that happens to have any pre roller bearing box at the end of the axle(s). But you may find a suitable illustration (X section) in any old book of which the copyright has expired. What ever you do have, post it on this talk page. I'd like to be able to compare visually. Peter Horn User talk 18:00, 21 May 2010 (UTC)

My scanner is still not available, so I put a special request on User talk:ArnoldReinhold#Obsolete bogies and bearings. Peter Horn User talk 17:58, 22 May 2010 (UTC)

Keith, my scanner is working and the X section is ready to be e-mailed to you but I can not find the button "E-mail this user" on your talk page. Cheers, Peter Horn User talk 04:40, 27 May 2010 (UTC) Ps my e-mail is peter.j.c.horn@gmail.com

See [8] and [9]

Journal box

Peter Horn User talk 20:01, 8 June 2010 (UTC)

Further to Andy's contribution above it needs to observed that a journal box is specific to a plain or journal bearing whereas an axle box may be designed specifically to house a roller bearing or a ball bearing. This is a subtle but important difference. See [10] Peter Horn User talk 02:31, 9 June 2010 (UTC)

A seperate section on plain bearinge as they apply to railway axles is now in order as well as a specific article about the journal box. Peter Horn User talk 02:29, 21 June 2010 (UTC)

Peter Horn User talk 02:49, 21 June 2010 (UTC)

Peter, we now have three images of railway related plain bearings crammed in the beginning of the article. Is this really necessary? Seems like WP:UNDUE weight is being attributed to their rail usage. Wizard191 (talk) 17:49, 21 June 2010 (UTC)

You are quite right. I just created the section plain bearing#journal bearings and moved one of the images down to the new section. Peter Horn User talk 22:47, 23 June 2010 (UTC)

^ Car and Locomotive Cyclopedia Of American Practice

Peter Horn User talk 02:01, 26 June 2010 (UTC)

I'm not sure that the journal bearing link in the image caption is such a good idea. No it isn't a good idea. What happened to Peter's section? Could we please make a journal bearing article and fix the links? SChalice 21:33, 30 January 2012 (UTC)

Conversions / equivalents

What are the metric equivalents of [sfm] and the formula of PV. Not all English speaking readers of Wikipedia are familiar with the customary units. Peter Horn User talk 15:32, 28 April 2010 (UTC)

Per this, it appears to be [m/min]. Wizard191 (talk) 18:08, 28 April 2010 (UTC)

Thanks, I put it as an external link. Peter Horn User talk 23:16, 28 April 2010 (UTC)

Since PV does not refer to the perfect gas law, what does it stand for or refer to? Peter Horn User talk 23:16, 28 April 2010 (UTC)

P is pressure and V is velocity. PV is the bearings ability to accept a combination of speed and load. You take the speed and load and multiply them and make sure it's less than the PV rating in the catalog otherwise you find a bigger bearing/better material/different design. Wizard191 (talk) 12:36, 29 April 2010 (UTC)

That would of course be pressure in psi and velocity in ft/sec. A note in the main text of this article would be helpful for the uninitiated like yours truly. An equivalent of MPa (or kPa) x m/sec probably exists. Conversion templates for sfm and PV, if they do not already exist, would be interesting. Cheers, Peter Horn User talk 13:06, 29 April 2010 (UTC)

See I've been a little bit hesitant to just come outright and say there is a metric equivalent. I use metric almost exclusively at work so all our bearings are metric and I've never seen them rated P, V, PV. I've only seen these ratings in psi and sfm. I just looked at my IGUS catalog (which is a German company) and all their PV ratings are psi and sfm. So I'm not sure if there is a commonly used metric equivalent, thought I could be wrong. Wizard191 (talk) 13:56, 29 April 2010 (UTC)

That is strange, the word catalog tells me that what you are looking at may be in German! I am going to google IGUS now. Peter Horn User talk 20:18, 29 April 2010 (UTC)

Or is it in English? Peter Horn User talk 20:51, 29 April 2010 (UTC)

According to the row of flags, IGUS catalog is available in 15 languages on line IGUS American English British English, German and 12 others. Peter Horn User talk 20:47, 29 April 2010 (UTC)

Mine is in English, seeing as that's all I can read. Here's a link to the part of the catalog that I was looking at (page 2 to be exact). Wizard191 (talk) 21:17, 29 April 2010 (UTC)

Well I think this clears it up. The German catalog lists PV as MPa x (m/s), so that is the proper metric conversion. (Note that the PDF is pretty big at 50 megs so if you are on a non-high-speed connection I wouldn't click on that link.) Wizard191 (talk) 21:31, 29 April 2010 (UTC)

And so does German IGUS, The last (bottom) box gives conversions. This was quite an exercise. Peter Horn User talk 22:22, 29 April 2010 (UTC)

Hi guys. Smid 2008 p. 74 gives m/min as the metric counterpart to ft/min. He also gives older speed-and-feed abbreviations that CNC programmers have used over the years that aren't used much anymore (in parentheses), such as MPM for m/min, FPM or SFPM for ft/min (=SFM, which is the abbrev still commonly seen), and IPM, IPR, and IPT, which mean inches per minute, revolution, or tooth, respectively. To work this info into the relevant articles is something that is in my to-do queue, but if anyone beats me to it, more power to them. Cheers, — ¾-10 00:28, 9 June 2010 (UTC)

clenched bushing

I don't understand the term "clenched bushing" used in the article. English is not my native language.
However, a clenched bushing is a bushing with a clench doesn't seem like an appropriate definition.

I updated the link to the wiktionary entry and will add a definition of a clench there. I'm also working on an image. Wizard191 (talk) 17:42, 6 December 2010 (UTC)

Attitude angle

Vertical is correct as far as I am aware - I'm looking at a UK Engineering Sciences Data Unit publication on journal bearing design, which shows the attitude angle measured from the vertical. --Andy mellor (talk) 18:09, 3 March 2013 (UTC)Andy_Mellor 3rd/Mar/2013

The text has:

The location of the journal is measured by the attitude angle, which is angle formed between the horizontal and a line that crosses through the center of the journal and the center of the bearing.

but the picture implies that the angle is measured from the vertical!

86.3.108.41 (talk) 08:04, 20 June 2011 (UTC)

Oil Whirl / Whip

I just updated the section on Oil whip and whirl to reflect usage prevalent amongst rotating machinery engineers, for whom these phenomena are important. I removed the section on backwards precession, because both oil whip & whirl produce forwards precession. It is only at the limit when the shaft begins to rub on the bearing (or some other part, e.g. a labyrinth seal or the casing) that backwards precession can occur. --Andy mellor (talk) 18:23, 3 March 2013 (UTC) Andy Mellor 3rd March 2013.

[1] Car and Locomotive Cyclopedia Of American Practice

[1]