Talk:Bearing (mechanical)

Text and/or other creative content from this version of Tribology was copied or moved into Bearing (mechanical) with this edit on 26 July 2010. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists.

Misleading caption

That figure title "An example of a radial ball bearing" is misleading... the image shows a Four-Point Contact Bearing with 2-piece Inner Race, sometimes called an "X Bearing with 2-piece Inner Race." The raceways are ogives in cross section. What is commonly called a "Radial Bearing" (also often called a "Deep Groove Bearing" or a "Conrad Bearing") has a semicircular raceway in cross section. [unsigned]

Thrust bearings?

Should some mention be made of thrust bearings? -- Izuko, 8/13/05

Commercial external links removed

I've removed a number of commercial external links, see here, and discuss if anyone feels that some should be re-added. If there are a few really notable manufacturers, it would be okay to link to just those, but it would be far better to use internal links for them, to discourage further non-notable manufacturers from adding themselves. --Interiot 06:25, 1 March 2006 (UTC)[reply]

Why not include some information regarding bearing numbering systems. eg 6204.2ZR.C3 6= bearing type radial ball bearing, 2=width series, 04= inside diameter 20mm (4mm x 5), suffix 2zr (metal shields), C3 = internal radial clearance larger than normal

Definition of bearing

"A bearing is a component used to reduce friction in a machine."

Come again? Really?? No. Oil reduces friction in a machine, so it's a bearing?

A bearing is a joint union between two items, one being the load & the other being the support, the point of contact being "the bearing". this can be between solid constructions "as in buildings" or between moving objects as in machines. The medium used between the moving parts to allow movement might be more accurately described as the race, sleeve or shell depending on the medium used. This medium is purely a friction reducer at the point of contact between the moving objects. The description below defines it further. —Preceding unsigned comment added by 86.146.0.153 (talk) 08:44, 26 April 2008 (UTC)[reply]

It seems to me that a bearing is something that *constrains* motions of parts in a machine. A *good* bearing reduces friction over a worse bearing, but sleeve bearings are still bearings. Oiling a sleeve bearing reduces friction, but the oil used isn't a bearing!WolfKeeper 19:56, 14 August 2006 (UTC)[reply]

Illustrations

This article really could use some illustrations - there are very good ones at Commons:Category:Bearings, but I'm not knowledgeable enough to assign them. There are also good photographs used in the German version of this article. Sandstein 05:42, 18 August 2006 (UTC)[reply]

Wow, those commons images are great! I've added several to rolling-element bearing. This is a more general article though, so it should probably have two or three images, of very different kinds of bearings. (eg. maybe one rolling, one flexure, and one plain bearing?). --Interiot 08:15, 18 August 2006 (UTC)[reply]

Types of bearings

I know there are many many types of bearings, especially if you include different mountings, but a list would be educational of non-experts. (E.g" cutlass bearing, pillow block, etc...)24.225.51.32 17:19, 10 October 2007 (UTC)[reply]

Explain! Explain!

This article leaves out the nonobvious things about bearings that I'd like to see explained by a knowledgeable person:

What is a caged bearing? (Don't tell when it was invented and not what it is!)
If a caged bearing is what I think it is based on the figure of the 4-point-contact bearing, don't the balls slide against the cage? What good are they then?

Yes, they do rub. But the force on the cage is low, because there's no great force pushing the balls towards each other, so the normal force between the balls and the cage is low, so the friction force is low too. The cage keeps the balls evenly spaced, so they don't all bunch up at one side.- (User) WolfKeeper (Talk) 04:00, 17 June 2008 (UTC)[reply]

Are there any bearings with no sliding contacts? How do they keep the balls/rollers apart?
Sometimes you hear about a sealed bearing. How does that work? It seems like sealing it tight enough to prevent leaking would lead to friction.

friction is how much normal force/unit area multiplied by area multiplied by the coefficient of friction. A seal has relatively low area.- (User) WolfKeeper (Talk) 04:00, 17 June 2008 (UTC)[reply]

A caged bearing is a device that uses a "low contact point or low friction" metal cage that runs in the ball or roller track with the balls or rollers to keep them apart & maintains a preset distance between them. If the balls or rollers were to come into contact with each other, their contact point would be extremely small, their contact speed would be double that of the bearing speed, the result is that the rubbing together at such speeds on such small contact areas generates intense heat and completely wrecks the bearing. The vast majority of ball & roller bearings are caged for this reason. The cage can easily be seen in a non sealed ball bearing as spacers between the balls.

A sealed bearing is a normal ball bearing that has the addition of rubber or plastic seals each side of the bearing to prevent ingress of dust particles etc. and to keep its pre-filled lubricant within. The seal is fixed to the outer race and has a lubricated low friction lip running on the inner race. These bearings are used mainly in places where regular lubrication is impractical ie, small domestic & portable equipment (drills washing machines & the like). —Preceding unsigned comment added by 86.146.0.153 (talk) 09:05, 26 April 2008 (UTC) - Mark Foskey 20:17, 13 November 2007 (UTC)[reply]

Cages are only used on rolling element bearings in a different article.- (User) WolfKeeper (Talk) 12:58, 3 June 2008 (UTC)[reply]

Firstly to answer the question about cages. No they are not restrictive in any way, they are designed to guide the ball/rollers/needles around the race.

Secondly your misconception that any bearing "slides" is false and a cage is one way used to prevent such things, sliding wears the inner and outer race and can lead to bearing failure. A bearing traditionally consists of : An inner and outer race, some sort of cage and a rolling element. Cages can be removed so that extra rolling elements can be added to increace capacity for RADIAL loads and seals (contact or non-contact) can be added to keep lubricants in and contaminants out.

hope I helped, i'll check back to follow up any further questions. I work for a bearing company and take part in a product training program here (i just got out of a lecture :)) 210.215.75.4 (talk) 00:45, 17 June 2008 (UTC) this is unsigned because I don't have the time or inclination to join a wiki project. ANDREW![reply]

Definition redux

I don't have time to follow up right now, but the blanket reversion of my recent edits won't stand vis-a-vis the edit summary given with it. Tweaking is welcome, but blanket reversion won't do here. Too many omissions were validly addressed by the additions. Will be back soon to revisit. — ¾-10 03:07, 14 April 2009 (UTC)[reply]

OK, after reading the articles on flexure bearings and living hinges, I understand better why my edits of last night cannot stand as written. Thanks for pointing me to those. Nevertheless, some of the info that my edits conveyed must still be duly incorporated into this article, although in modified form. For example, in 19th- and 20th-century scraping practice, it was common to speak of "scraping to a bearing," by which they meant scraping to approach the final geometry and surface finish of an accurate, smooth plane or cylindrical surface. Such accurate surfaces would then serve as bearing surfaces such as ways and spindle bearings. So we need to broach in this article the very idea of a bearing surface as simply a careful preparation of the substrate's geometry and surface finish. This is "square one" from which bushings and linear bearings build in complexity. When I have "free time," or a synthetic approximation thereof, I'll work on incorporating this info in a way that also keeps in mind the broadest sense of the word "bearing" including flexure bearings and living hinges. Thanks, — ¾-10 00:11, 15 April 2009 (UTC)[reply]

Update: Haven't had time to come back to this, but I will note here for future development that when you consider flexure bearings, the simplest journal bearings, and scraping ways to a bearing, you must define the broadest sense of the word "bearing" not as "a device to allow constrained relative motion between two or more parts", but as "an interface to allow constrained relative motion between two or more parts". The "device" sense is the next step down in breadth (but still fairly general) and is the sense most frequently used. Will work on a revision sometime if the spirit moves me. Regards — ¾-10 22:50, 5 June 2009 (UTC)[reply]

Given that an interface is an infinitely thin surface I kinda doubt that that's what a bearing is. Got a reference?- (User) Wolfkeeper (Talk) 23:41, 5 June 2009 (UTC)[reply]

I'm referring to the broadest sense of the noun interface (ie, the way that two objects [or two components of the same object] interact); whereas you're referring to a step down in breadth (ie, one of the subsets of that superset). There is a logical connection that links those two senses, but I don't yet know if the world of existing secondary sources contains any good instances of someone having written a clear exposition of that connection. Such instances are what I would need to find as refs. I may not get the time to pursue this. If anyone else out there who's reading this does, feel free to follow up. Regards — ¾-10 16:50, 6 June 2009 (UTC)[reply]

Here's a site with photos of an integral cast iron bearing. Also talked about in this book. — ¾-10 03:16, 24 November 2009 (UTC)[reply]

For the record here, a link to this discussion, related to the same superset topic (the various senses of the words), from when "Bushing (isolator)" was called "Bushing" and was conflated and merged with "Plain bearing" (ie, the Venn relationship of the overlapping senses was not represented correctly by the former page naming logic). When I get a chance I will move the "to bear/bearing/to be borne" info here and fill in the references. — ¾-10 02:34, 11 December 2009 (UTC)[reply]

Looking forward to it...the definition needs to be fleshed out more for sure. Wizard191 (talk) 17:53, 12 December 2009 (UTC)[reply]

Stiffness

A footnote in the Types chart says "Stiffness is the amount that the gap varies when the load on the bearing changes." Wouldn't it make more literal sense to say that stiffness is the amount that the gap doesn't vary, or the magnitude of the gap's resistance to variation, or something like that? —Deadcode (talk) 07:22, 3 March 2010 (UTC)[reply]

Perhaps, but at least one place measures stiffness as deflection per unit load: [1].

As a side note, here's two interesting papers about bearing stiffness: [2] & [3]. Wizard191 (talk) 15:26, 3 March 2010 (UTC)[reply]

history

As it is obvious that rollers and wheels are related technologies a statement to this effect now introduces the history section.

There is no evidence that the ancient egyptains used rollers or that they invented them. The former is entirely archeological speculation, the later certainly not true (see invention of the wheel). Actual egyptian art depicts sleds on lubricated runners without rollers. The references for the current statement do not link to a viewable document, one links to an engineering association, the other to a website selling copies of their proceedings.

I suggest that Egyptain use of rollers is more accurately described as speculation hence my previous text alteration as follows:

"Though it is often claimed that the Egyptians used roller bearings in the form of tree trunks under sleds[2] they are depicted in their own drawings as moving massive stone blocks on sledges with the runners lubricated with a liquid which would constitute a plain bearing. This may have been because there were few trees in Egypt adequate for this task and that under the weight of the larger stones any logs small enough to be man-handled into position to form a continuous rolling surface would have quickly deteriorated."

Evidence, in the form of a real ancient illustration (not a modern "theory") can be found by Googling Djehutihotep. The illustration shows a massive statue on a sled but without rollers. — Preceding unsigned comment added by Cymtriks (talk • contribs) 12:28, 15 April 2011 (UTC)[reply]

Please comment. — Preceding unsigned comment added by Cymtriks (talk • contribs) 12:00, 15 April 2011 (UTC)[reply]

Please review Wikipedia:Verifiability; Wikipedia's policy for inclusion is verifiability not truth. Moreover, you are pushing lots of original research, so unless you have solid secondary references to cite, its just speculation. Wizard191 (talk) 13:18, 15 April 2011 (UTC)[reply]

The use of rollers in ancient Egypt is speculation, all the citation is doing is referencing a source that itself is speculation and not verifiable. The source material in the form of actual ancient pictures clearly shows sleds without rollers but with lubricant being applied to the runners. I am puzzled as to why this is deemed original research, if anything claims that rollers were used is original as it ignores the source material. I'll dig out some references to documents based on history and try to verify the copyright status of the tomb wall paintings. Hopefully that will bring any changes in line with the rules.

Comments welcome! — Preceding unsigned comment added by Cymtriks (talk • contribs) 21:43, 15 April 2011 (UTC)[reply]

Ball retainer

There should be some mentioning of 'ball retainers'. These are some kind of torus or ring shaped structure which can hold the balls in place. See:

http://www.p-wholesale.com/upimg/19/730a1/ball-retainer-288.jpg

I think that the only serve the purpose of keeping the balls in place when placing it there, and in theory, if you could remove the retainer itself after assembling whatever, that would make no difference.

They are often used in bicycle hubs. I have not seen them elsewhere.

80.162.194.33 (talk) 09:18, 3 August 2011 (UTC)[reply]

This would be a good addition - they're a common part of many bearings, although they're more often seen in plain radial load bearings. As bike hub bearings are specialised for an angular contact path (radial and axial forces on a single bearing), they have this unusual shape.

As well as aiding assembly, they're also sometimes important for keeping the balls equally spaced, thus avoiding the balls shifting to one side under an asymmetric load. Andy Dingley (talk) 09:58, 3 August 2011 (UTC)[reply]

Friction Rollers

Friction roller search. New article section or new friction rollers wiki page? HonestIntelligence (talk) 09:24, 6 June 2012 (UTC)[reply]

A new section in roller conveyor. Their function is for materials handling, not about bearing design. Andy Dingley (talk) 10:41, 6 June 2012 (UTC)[reply]

Simple Carts etc

Much of the article seems to relate to modern bearings. What bearing would a simple cart, or a 17th Century carriage, or an American wagon (as in a wagon train) have used? Ball bearings would seem to be too advanced a technology for these. Would they usea plain bearing with the wooden contact points lubricated with grease?Quentin Durward (talk) 11:39, 7 August 2016 (UTC)[reply]

Many variations, but typically wood against iron, lubricated with tallow. Many such bearings were "iron shod", meaning a wooden structure on both sides, but with one - usually the axle - wrapped in a thin iron plate. The wood used would depend on what was available, but elm was popular and made good wheel hubs too, as the interlocking grain meant that it remained strong even in thin sections. Tropical timbers, especially lignum vitae, were imported and used too.

Later, cast iron became a cheap structural material. This became widely used for plateway wheels, on a wrought iron axle. These wheels were strong, cheap in small sizes (they didn't need a skilled wheelwright to make them) and were long-lasting in wet mine conditions, but they were heavy and didn't react well to shock loads, so weren't usable on the poor roads of the day. Wrought iron did become used for light carriage axles as it was strong enough to be made lighter and thinner than wood and could also be shaped as a dropped axle. Brass was adopted as a bearing for wood over wrought iron, as less brittle than cast iron.

Lubricants were animal grease and fats for a very long time. This is cheap, available everywhere, and stays in place once applied. Oil wasn't used much as a lubricant until complicated shaped cast iron bearing boxes with an oil bath could catch the expensive run-off and exclude dirt. These appeared first on steam engines, then on faster railway passenger coaches and later on railway good wagons. Well into the 20th century, some railway goods wagons still used grease axleboxes. Andy Dingley (talk) 08:47, 9 August 2016 (UTC)[reply]

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The "Rolling-element bearing outer race fault detection" section does not belong with this article

Imagine that you had an eigth-grade textbook on bearings and in the middle of it you inserted a paragraph out of a someone's PhD dissertation about bearings. That's the situation with the "Rolling-element bearing outer race fault detection" section. It's not that it's wrong, but that it's just at a completely different level than the rest of the article. That same amount of space could be much better used to cover a more general topic about bearings. Someone who is an expert in this material should remove that section and add some more general material. — Preceding unsigned comment added by 96.37.224.164 (talk) 07:00, 18 September 2017 (UTC)[reply]

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