Talk:Pulley

Vandalism question

This page seems to get an unusually high incidence of vandalism. Normally, a page has to be either a featured article or a very public and controversial topic to be vandalized this regularly. Any hypotheses about why this page is so regularly attacked? Rossami (talk) 20:21, 28 February 2006 (UTC)

Pretty sure "Pulley" is British slang for Handjob. I've heard it a few places across the web. I'm assuming that's it's consistently vandalized. Restocking (talk) 18:59, 12 November 2012 (UTC)

Theory of operation

I added a theory of operation section, and used two of the pulley system images from the original article. I have removed the simplest compound pulley image, because its practical implementation is not different from the diagram, which is the case for the other two - they are different from the diagrams. I also removed the "historical images of pulleys" because it didn't seem to add much, without an explanation. Maybe it could go back in under a history section? PAR 04:51, 5 March 2006 (UTC)

how about the diameter of the wheel? doesn't that have something to do with the force necessary to lift an object? —Preceding unsigned comment added by 208.71.200.85 (talk • contribs)

Nope, nothing. The forces on either side of the pulley are the same regardless of the radius of the wheel.
Okay, actually that's for a theoretical pulley. A real pulley will suffer some slight amount of friction between the fibers of the rope as it goes around the pulley. A larger diameter pulley will deform the rope less resulting in slightly less friction. But that is a miniscule effect compared to the normal forces used on the pulley. Rossami (talk) 00:24, 8 September 2007 (UTC)

Bicycle chain pulley?

Is it correct or incorrect to call the non-driven wheels in a modern bicycle rear derailleur pulleys? The chain is kept in place by its side-plates and small "near-teeth" in the pulley, rather than by fitting in a groove. This particular application also involves no mechanical advantage--just tension adjustment. Are there other applications where chains and wheels function as cables and pulleys?--SportWagon 23:28, 18 August 2006 (UTC)

In the context of the six simple machines, yes, a derailleur would be considered a pulley - specifically a "class 1" pulley with a mechanical advantage of 1. The fact that the "groove" is on the chain rather than on the wheel is a minor variant. The definition of something as a simple machine is based on how the force is transformed as the force does work. Any situation where the force is being carried through tension and where the direction is changed would probably count as a pulley. Rossami (talk) 12:13, 19 August 2006 (UTC)

Sheldon Brown had these entries in his glossary: -AndrewDressel (talk) 21:43, 4 June 2010 (UTC)

• Idler: "An idler is a pulley or roller that does not produce any mechanical advantage, nor transmit power to a shaft. Idlers are used to lead a chain around a bend (as in short wheelbase recumbents), or to take up slack in a drive chain (as in a tandem chain tensioner, or the pulleys in a derailer."
• Chain pulleys: "Most rear derailers use two pulleys in a spring-loaded cage to regulate the tension of the chain as it runs over different sized sprockets. The upper pulley is called the "jockey" pulley, the lower one is the "tension" pulley."
• Jockey pulley: "The upper pulley on a rear derailer. This is the pulley that actually guides the chain from one sprocket to another. Shimano jockey pulleys are designed with a "Centeron®" mechanism that allows a small amount of sidewards motion to compensate for imprecise index adjustment."

Additional Information Needed

I think information should be added to this article to recognize a "sheave" as a type of pulley. I'm probably not the right person to add this, but I do know that they are commonly used in oceanic applications suspended from an A-frame on a ship and also for oil drilling. 65.165.72.203 17:17, 18 October 2006 (UTC)Tired_Angel

Regarding Pictures

Bad picture. The pulleys shown are what are called belt pulleys. A rubberized loop of belt wraps around both pulleys. One pulley is the source of power, the other receives power through the belt. This was a common way to transfer rotational power prior to about 1940. Threshing machines received power through the belt and belt pulleys from the steam engines.

A picture of the type of pulleys described in the article is needed. Also the article should also mention belt pulleys as well. --69.5.156.155 06:22, 24 Sep 2004 (UTC)

Diagram 2a is INCORRECT. The upper arm to the left holding the upper left pulley is labeled with W. It does not support W, it supports W/2. I will attempt to fix and submit corrected image. Also, the Image to the right, the "Practical Compound Pulley" system is not the same as shown in Diagram 2a. Further examination also reveals that the next set of diagrams is incorrect. As I cannot seem to upload images yet I am hiding the content that is incorrect. —Preceding unsigned comment added by 71.186.138.85 (talk) 11:00, 24 April 2009 (UTC)

You didn't add this comment at the bottom, so I missed it, I thought the article was being simplified rather than an attempt at correction. Diagram 2a is CORRECT. The total upward force is 3W/2, the total downward force is 3W/2 (you probably neglected the W/2 force downward on the rope on the left which causes the entire system to be in equilibrium.) Regarding the "Practical Compound Pulley", the key word is "Practical". This is not the same as "Identical". The rope connecting the right pulley to the upper support is instead connected to the axle of the left pulley, which is in turn connected to the upper support. There is no essential difference here as far as the tensions in the ropes or the advantage of the pulley. The same is true of figures 4a and 4b. PAR (talk) 19:34, 24 April 2009 (UTC)

PAR: I am an idiot. Please excuse my misguided attempt at "fixing" the article. —Preceding unsigned comment added by Legrand68 (talk • contribs) 14:01, 25 April 2009 (UTC)

LOL - No problem, if making a mistake makes one an idiot, then I'm in BIG trouble. PAR (talk) 11:32, 26 April 2009 (UTC) -

LOL - No problem, if making a mistake makes one an idiot, then I'm in BIG trouble. PAR (talk) 11:32, 26 April 2009 (UTC) -

Re:Leavenworth Arrangement

Rossami: I am not quite sure how to use this system, but the Leavenworth Arrangement has not been known since Archimedes. It took me a year to discover, and I am an intelligent fellow. You will not find this knowledge in books, because this is the first time it has been published. If you are of the opinion that knowledge is never lost and rediscovered, or that such a thing could not be discovered in this day and age, I challenge you to find fault with the math, with the arrangement, and a previously published source describing the arrangement. Besides those objections, there can be no reasonable objection to the additions.--MarkLeavenworth 03:01, 19 October 2007 (UTC)

@Mark: wikipedia has a very strict policy about original research: it is not accepted. See this page Wikipedia:No original research. VanBurenen 07:52, 19 October 2007 (UTC)

I'm sorry you've misinterpretted the meaning of 'verifiable'. 1)The math does not warrent the necessity of citing for verification on the grounds that it is too simple. 2)The arrangement does not necessitate citing for verification on the grounds that it is too simple. 3)Only you can dispute my right to name the arrangement, if you can provide enough verifiable citations in the public domain to dispute my claim that I have rediscovered this technology. —Preceding unsigned comment added by 66.81.190.202 (talk) 15:32, 19 October 2007 (UTC)

You have been asked several times now to go read the Wikipedia policy against original research. It does not matter how obvious or self-evident you think this is. Encyclopedias are, by definition, tertiary sources. We synopsize the writings of others. Until it is verifiably published in a reliable source, it has no place in the encyclopedia. Either cite your sources or stop adding this content. Rossami (talk) 21:47, 19 October 2007 (UTC)

"The threshold for inclusion in Wikipedia is verifiability, not truth." OH, I see this is not an encyclopedia of knowledge, but an encyclopedia of that which is verifiable. I'm sick to my stomach and ALARMED to learn that so many Americans have been tricked and trapped into believing that TRUTH is not VERITY. Especially since this Wikipedia effort was launched to open the way for the free exchange of knowledge. You people, having taken over the effort through subtlety, are proving to be a CLEAR and PRESENT danger. If my concern is not warrented, I suggest you open an editorial chain of command for original contributions that claim to be self-evidently true.—Preceding unsigned comment added by 66.81.191.38 (talk) 04:10, 20 October 2007 (UTC) --66.81.190.29 19:10, 22 October 2007 (UTC)

Uhm, maybe this is just too obvious, but isn't this entire entry made up original research? There isn't a single source sited on it. If the Leavenworth arrangement works, then it is just a valid as all the other unsited information on this page. Siting sources is important but there isn't there some allowance for the duh factor? Should the number 10 entry and all its occurrences be removed from wikipedia because there are no references sited? Does someone need a reference to say the sky is Azure on a clear bright day? Come to think of it, there are no references to indicate user:VanBurenen even exits, or user:MarkLeavenworth, or myself for that matter. We need to all be deleted from wikipedia promptly. —Preceding unsigned comment added by 76.191.180.179 (talk) 10:30, 29 February 2008 (UTC)

To clarify the original correct reason for the edit: Rossi had taken the liberty to make an ideal diagram of multiple pulleys, with even fractional mechanical advantages distributed to each. The point of the edit is that such an arrangement does not function in practice. The problem is worse than friction; it is the imbalance caused by forces of friction that are different with each wheel. For example, if each wheel loses 10% of the pulling force to friction, the first line will have a 90% pull whereas the second wheel will have an 89% pull. The precise math is more complicated, but the end result is a system that cannot function as diagrammed by Rossi. To correct for this practical problem, each end of each line must be grounded to the load on one of the sides so that the friction through each pulley is the same and the lines can pull together. Alternatively, with more care and difficulty, the load can be adjusted so that its center balances at the center of the forces of friction, which incredibly might extend beyond the system in order to obtain the leverage necessary depending on the ratio of the friction to the load. — Preceding unsigned comment added by 2602:306:BCE9:2280:E16C:699F:A80A:EA71 (talk) 23:01, 15 November 2017 (UTC)

Weston Differential Pulleys

i see nothing on these fascinating pulleys. would anyone be willing to write anything?

Chris(talk) 18:03, 23 October 2008 (UTC) —Preceding unsigned comment added by 86.28.101.3 (talk)

See differential pulley. (I'm not familiar enough to know if the Weston design is significantly different from the generic "differential pulley" design.) Note: That article could probably use expansion if you have time and interest. And this article should probably include a "see also" link. Rossami (talk) 18:19, 23 October 2008 (UTC)

Ahh yes, that the one. my google search with wiki at the end failed me! Still, I'm surprised its not mentioned in this article. And I don't think I'd be a good person to contribute to this article, my grammar is terrible! Thank you Dyslexia. Chris(talk) 23:52, 23 October 2008 (UTC) —Preceding unsigned comment added by 86.28.101.3 (talk)

New images

Made following new images, could be implemented to article: thumb|right|75px thumb|right|75px

Timing belts

Belt-drive on a belt-driven bicycle, but is that a sprocket or a pulley?

Do timing belts, and other ribbed belts run on sprockets, notched pulleys, or something else by another name? What distinguishes a pully from a sprocket? The teeth, the flanges, or what runs on them, a belt or a chain? Does anyone have a definitive reference, or is this just a murky area?

This is essentially the same question as was asked about bicycle chains above, I think. So in the context of the six simple machines, yes, a timing belt arrangement would be considered a pully with a mechanical advantage of 1. The Oxford English Dictionary (the only citation currently on the page) sets a different definition - one based on a perceived need to differentiate between specific kinds of things that act as a pulley. OED requires a pulley to have flanges. The simple-machine definition is based more on the transformation of forces. Rossami (talk) 21:25, 4 June 2010 (UTC)

Similar, but that was asking about wheels over which a chain runs. This is asking about wheels over which a belt runs. I believe the context of simple machines is no help in this case, because pulley and sprocket appear to be the same simple machine. OED does not require pulleys to have flanges. See definition "c. A wheel or drum fixed on a shaft and turned by a belt, cable, etc., for the application or transmission of power, or to guide the belt." -AndrewDressel (talk) 21:38, 4 June 2010 (UTC)

I misspoke about OED requiring flanges. Thank you for the correction. Nevertheless, my point is that a pulley and a sprocket are the same simple machine. Modern usage carries the connotation of ribs or chains for "sprockets" (fairly strictly) and relatively smooth ropes or belts for "pulleys" (more loosely) but they share exactly the same mechanical concept and can both be referred to as pulleys in the larger sense. Rossami (talk) 21:52, 4 June 2010 (UTC)

Mounting

A very large section was recently added to this article focused on the "Methods of mounting" a pulley wheel to a shaft. I have removed the section pending discussion here because

1. It is not unique to pulleys. Any structure fixed to a shaft would use the same techniques.
2. The level of detail is disproportionate to the rest of the article
3. The writing style encroaches on the WP:NOTHOWTO prohibitions

If anyone can recover useful content from the section, it can be found in the collapsed content immediately below. Rossami (talk) 21:44, 4 June 2010 (UTC)

Methods of mounting

Methods of mounting Pulleys are commonly mounted to shafts in the following ways: Interference fit Variations: Interference fit alone Interference fit and key (key may fasten by press fit, taper, or both) Interference fit, key, and set screw above the key Assembly: Application of heat expands the pulley, temporarily removing the interference long enough to ease the assembly. The heat can be supplied from heat guns or blow torches; the former are gentler to the paint and metal tempering. Pressing via shop press, arbor press, or hammer can also be used. Caution is required, because excessive axial pressing or hammering can damage the bearings of the shaft. Heating the pulley helps to avoid this by reducing the amount of axial force needed. Disassembly: Bearing pullers are tools that grip the pulley (or bearing or gear) with jaws while a screwing action pulls it off the shaft. Methods using screw threads Advantages: These methods are advantageous (compared to press fit) because in the field, no heat or pressing are needed to do the assembly or disassembly. Variations: Set screw alone (suitable for low-torque applications) Split taper bushings Principles: These work on the same basic principle as collets. The pulley's bore and the bushing's OD are both tapered. Threaded fasteners hold the pulley to the bushing, wedging the tapers to the point that they hold fast, and squeezing the bore of the bushing against the shaft, causing that interface also to hold fast. Typically keys are also used as further insurance against relative rotation. Variations: Custom (bespoke) bushings Quick-disconnect (QD) bushings, a standardized subset of split taper bushings, available off the shelf from industrial supply houses Bolted joints The face of the pulley may be bolted to a flange on the shaft. The flange may be an integral part of the shaft or be a separate part that is pressed, welded or otherwise fastened to the shaft. Threaded shaft The shaft end may be threaded, allowing a large nut to fasten the pulley directly against a shoulder behind it

I agree with point 1, disagree with point 2, and strongly disagree with point 3. As such, I think the above text should just be moved to drive shaft. Wizard191 (talk) 18:10, 6 June 2010 (UTC)

mistakes in two figures

There was a subtle mistake in two of the figures. In diagrams 3 and 3a, horizontal bars are used to add two forces. In the original version of the figures, the weight was suspended below the midpoint of the bar. This would cause the bar not to be in equilibrium; it would twist clockwise. To make the system function as intended, it's necessary to slide the weight over to a position 1/3 of the way over from the left. I'm in the process of correcting the two diagrams.Fashionslide (talk) 18:58, 18 September 2011 (UTC)

Pulley as a simple machine

This article is linked to the article simple machine as one of the six simple machines identified by Renaissance scientists. It is therefore one of the articles used by elementary school teachers when they introduce technology and mechanical advantage. I would like to make some revisions to this article that include this historical perspective while maintaining the spirit of modern machine theory. I will work to avoid disrupting other content in this article. Prof McCarthy (talk) 16:46, 11 December 2011 (UTC)

Support. Excellent suggestion; excellent plan. — ¾-10 16:55, 11 December 2011 (UTC)

Colleagues, I am sorry that it took so many revisions to get the figures organized correctly. I somehow thought this would be easy and it was not. I realize now that I should have copied it to my sandbox and made the revisions there. None-the-less, I believe this version is better in describing the basic principles. I removed a lot of text that I thought was redundant. If this causes concerns, please put back what you think is needed. I just wanted to get this basic structure in place. Thank you for your patience. Prof McCarthy (talk) 07:20, 13 December 2011 (UTC)

Upward and downward direction of pulley rope

A new section has been added to this article describing a method for the calculation of the mechanical advantage of a block and tackle system by using a count of the upward direction and downward directed rope. As far as I can tell this assumes that an assembly of pulleys into a block and tackle lifts a load vertically by pulling downwards on a rope. It is not clear how this is calculated if the pulley system is used to pull a load horizontally along the ground, particularly if the pulley system is configured to pulling the the same direction as the movement of the load. Prof McCarthy (talk) 23:37, 30 October 2012 (UTC)

Step Pulley?

Is a step pulley one of these types? If so can we have a section on it?

IceDragon64 (talk) 22:27, 9 November 2014 (UTC)

Yes—that's funny, I thought we had a mention already in this article, but I just hit ctrl-f for "step" and found nothing. A step pulley is to V belts exactly what a cone pulley is to flat belts. (In fact, it is nothing more than idiomatic accident that the names are not interchangeable—the concept is identical). I will add a mention. — ¾-10 00:37, 10 November 2014 (UTC)

History

There's nothing really on the history of this machine. I would've thought that would be significant given the fact that the pulley is one of 6 simple machines. Rayman60 (talk) 19:08, 27 November 2015 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Pulley/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

== Origin of pulleys? == I'd like to see more information on when pulleys hit the scene. I assume the first ones were wood, and might not preserve well, but they must be some type of archeology on the topic. Cpurrin1 00:39, 20 October 2007 (UTC) Colin Purrington == addition to the article == The article is very informative. I suggest that following link of Khan Academy be added to the article for the benefit of the reader. http://www.khanacademy.org/science/physics/mechanics/v/mechanical-advantage--part-3 — Preceding unsigned comment added by 58.175.48.247 (talk) 01:36, 3 December 2012 (UTC)

Last edited at 01:37, 3 December 2012 (UTC). Substituted at 03:33, 30 April 2016 (UTC)

Possibly updated link: https://www.khanacademy.org/science/physics/discoveries/simple-machines-explorations/a/pulleys JimBob128 (talk) 19:48, 17 June 2022 (UTC)JimBob128

One-pulley hoisting systems

A one-pulley hoisting system

All hoisting systems described use at least two independent pulleys, invariably housed in blocks. Obviously, something needs to support a pulley's axle, which can be a simple U-shaped piece, as in the accompanying picture. Does that qualify as a "block"? And what about one-pulley systems? The picture shows one very common configuration of a rope and pulley system involving precisely one pulley, yet the article states that "rope and pulley system" means the same as "block and tackle", which the latter article defines as "a system of two or more pulleys". Also, the description here refers to "the set of pulleys that form the moving block", implying that there is always a pulley that moves with the load – which need not be the case, as shown in the picture.  --Lambiam 08:46, 6 June 2018 (UTC)

Add info on "pulley lagging"?

http://www.ckit.co.za/secure/conveyor/troughed/pulleys/pulley_lagging.htm:

>>>Lagging is the term used to describe the application of a coating, cover or wearing surface which is sometimes applied to pulley shells.

>>>Lagging is often applied in order to extend the life of the shell by providing a replaceable wearing surface or to improve the friction between the belt and the pulley. Notably drive pulleys are often rubber lagged for exactly this reason. — Preceding unsigned comment added by 46.166.187.95 (talk) 00:47, 27 June 2018 (UTC)

-- Done. This was very interesting and I want to thank you for bringing it up :D Btw, idk how you found that website but it has TONS of info. JimBob128 (talk) 21:37, 17 June 2022 (UTC)JimBob128

Proposed merge of Sheave into Pulley

I'm proposing that this article Sheave should be merged into Pulley, as the sheave is part of a pulley. Furthermore, the article hasn't had any change and lacks any inline citations. In my opinion, the merger would likely not cause any opposition, and wouldn't cause any harm to anyone's current plans to edit it. Explodicator7331 (talk) 15:58, 18 February 2022 (UTC)

Agree that the terms are interchangeable despite some geographical or industry specific differences. As such I would support the merge with the proviso that a note is included in the body of the page as to the interchangeability Spacey (talk) 08:45, 5 May 2022 (UTC)

I third believe that the articles Sheaves and Pulley should be merged due to 1)Sheaves seems to be only significant to Pulleys, 2)Sheaves is a very small article, not a gigantic topic that needs its own page. 17 June 2022JimBob128 (talk) 19:41, 17 June 2022 (UTC)JimBob128

  Y Merger complete. Klbrain (talk) 10:05, 27 December 2022 (UTC)

Science

What a 3 body of pulley 136.158.124.59 (talk) 12:23, 18 April 2022 (UTC) Can you please expound? If not, this comment will eventually be deleted. JimBob128 (talk) 21:19, 17 June 2022 (UTC)JimBob128