Talk:Gear

message: I think this paragraph in the article is completely irrelevant to the article and should be deleted. Comments?
"There are several outcomes of gear shifting in motor vehicles. In the case of air pollution emissions, there are higher pollutant emissions generated in the lower gears, when the engine is working harder than when higher gears have been attained. In the case of vehicle noise emissions, there are higher sound levels emitted when the vehicle is engaged in lower gears. This fact has been utilized in analyzing vehicle generated sound since the late 1960s, and has been incorporated into the simulation of urban roadway noise and corresponding design of urban noise barriers along roadways.[2]" -- Dalebert 10/19/07  —Preceding unsigned comment added by 192.158.61.142 (talk) 12:39, 19 October 2007 (UTC)
thread_title:  Is this relevant? 

message: I need design procedure for winch means all the components of winch and how to design them
How about some nomenclature, such as pitch etc.
Also maybe some of the physics involved (torque ratios etc) 7legs 010306
:I think you need more help than Wiki is prepared to give you. Perhaps someone can refer you to a good textbook or handbook?
:Atlant 15:16, 1 March 2006 (UTC)
replies: text: I do not think one sets out design a gear train. In this case it is a winch, motorised or otherwise to launch a boat ? Start with the motor you have, then the load you want to move and then you can design a gear train that will get the job done in a certain amount of time..
Gregorydavid 07:52, 16 May 2006 (UTC)
thread_title:  Help me design a gear train 

message: This can be tricky.. Each gear has its own axis of rotation. Two gears have their respective axes of rotation.. In a train of gears there is the axis of rotation of the input and the output which can have the same orientation in space, ie along the X axis..
But changing my changing 'axes' to 'axis' yesterday wa wrong..
Gregorydavid 08:11, 16 May 2006 (UTC)
thread_title: Axis versus Axes

message: I took some photographs of gears from a Meccano construction set to make these images. Arthur Clarke 17:48, 31 July 2006 (UTC)
replies: text: I think the photo of helical gears is misleading - the upper pair don't appear to be parallel helical gears, they're the same crossed gears that appear in the lower half of the image, but shown in a parallel orientation.  As pictured, the teeth would not mesh correctly.  As stated in the text, in order to mesh correctly one gear would need its teeth to helix in the opposite direction to the other. 62.189.196.126 (talk) 13:24, 19 May 2010 (UTC)
replies: text: Yeah I see what you are saying. Unfortunately the only way to fix it is by taking a new photo. Wizard191 (talk) 18:00, 20 May 2010 (UTC)

text: We are talking about the helical meccano gears not the double helical gears. Wizard191 (talk) 22:41, 24 June 2010 (UTC)
thread_title: Added Images of Helical Gears and a Worm and Pinion

message: I removed the US specific annotation "stick shift" against the reference to Manual transmission as there is already a redirection from "stick shift" and Manual transmission is the primary, and more explicit, title. Arthur Clarke 17:48, 31 July 2006 (UTC)
thread_title: Removed US Specific Annotation

message: I put this in the discussion because I've never edited a Wikipedia page before... so I'm shy, big deal.  If anybody else wants to incorporate my suggestions, feel free.  For reference authority, it's probably tough to beat Machinery's Handbook (practically any edition since the late Bronze age).
Double helical gears:  A *train* of herringbone (double-helical) gears can usually (see below) be used instead of a train of spur gears without any need for different bearings because neither require bearing for axial thrust.  However, it is *not* true that herringbone gears [of nonzero helix angle] "can be interchanged with spur gears" [of finite face width] because the teeth won't mesh (unless all gears in the train are 'interchanged', or in the trivial case of zero helix angle that doesn't warrant the 'herringbone' designation).
Note also that a pair of herringbone gears will mesh in only one axial position, aligning both helix angles of each gear.  Spur or helical gears, on the other hand, can remain in mesh if one is axially displaced relative to the other.  Which is advantageous (or disadvantageous) depends on the machine, of course.
It's probably worth noting the two obvious (but obviously incompatibale) standard ways to make a double-helical gear:  The two opposing helices might meet in the middle of the gear with (a) addenda (teeth) from each helix coincident, or  (b) addenda of one helix coincident with dedenda [spaces] of the other.  The latter are "Wuest" herringbone gears.
Double helical gears:  The teeth aren't "V-shaped", their shape of their flanks are involute (usually, though other forms also give correct action) just like those of spur and helical gears.  I realize that profile isn't what the writer refers to, but IMO too few people appreciate that (non-rack) gear teeth are *not* v-shaped in transverse section.  There must be a better way to say what is meant here, though nothing pops readily to my tiny mind.
Bevel gears:  Should read "where two axes [not axles] cross at [a] point".  Nothing really difficult about crossing axles at a point, except (a) difficult to arrange so both can rotate, and (b) it's generally not a feature of actual bevel gear sets (e.g. the floodgate example photo)
Bevel gears:  While it's true that helical gears can be arranged to provide for "ninety degree rotation" of the *projected* axes of rotation, (a) the existing text is too limiting; helical gears can provide for any such angle, not just ninety degrees, and (b) the existing text omits an important detail; the two axes cannot be coplanar [except for the 'trivial' case of parallel axes]
It may be worth noting that internal and external spur gears are special limiting cases of bevel gears.  Bevel gears mesh between coplanar axes; the term is generally reserved for intersecting axes.  Ordinary (external) spur gears are one limiting case of parallel axes, i.e. zero pitch "cone" angle; internal spur gears are another limiting case of parallel axes, i.e. pitch "cone" angle of 180 degrees [though most spur gears use involute teeth and standard bevel gears use octoidal teeth, that's merely a standards-implementation detail].  Similarly, spur gears are a limiting case of helical gearing, i.e. zero helix angle.  [It's not clear {to me, anyway, and I know no reference} whether helical gearing is a case of the various standard forms of spiral bevel gearing {e.g. Gleason's Coniflex, et al; I suspect not}].
Worm gear:  The part that looks like a screw is a *worm*; the wheel with which it mates is the *worm gear* (well, usually; a worm will mate with spur and helical gears of corresponding tooth form and normal pitch, but only in point contact that is suitable only for light loads rather than the broader "line contact" it would achieve with a proper worm gear).  The teeth of a worm gear extend across its concave face to contact the worm teeth through a greater angle of the worm's rotation.  That is a worm and worm gear are *not* a special case of helical gearing (a worm might be a special case of a helical gear, though standard worm thread forms differ from standard helical gear teeth).
Worm gear: (same guy, later date):  It is incorrect to claim that the worm is *always* the driver.  It is *often*, but not always, true that the worm and gear are "self locking (the gear cannot drive the worm).  If the helix angle of the worm is sufficiently high for the coefficient of friction between the worm and the gear, the gear can drive the worm.
Sector gear:  Is merely a segment of a gear, which is not necessarily a spur gear.  In the mentioned example of automotive steering gear, the sector gear is a typically a segment of a worm gear, not a spur gear.
Rack and pinion:  Not limited to spur gears.  There's nothing un-gearlike about helical pinions mating with skewed -- or even straight -- racks as long as the systems can deal with -- or profitably employ [e.g. backlash takeup] -- the resulting thrust or displacement. [no, I don't have any handy example].  The rack is a special case of spur (or helical) gear, with infinite pitch diameter and tooth count; all real racks are therefore special cases of sector gears.
Crown gear:  Does *not* mesh correctly with a spur gear pinion [of finite face width].  A crown and spur gear could be made to turn each other through point contact at the ends of the teeth nearest the crown gear axis, but that would still not transmit uniform angular motion because the radius to the point of contact would vary as teeth engage and disengage.  A crown gear is a special case of bevel gear (90-degree pitch cone angle); a bevel gear is required for correct mesh because the size of the crown gear's teeth (and spaces) vary with distance from its axis.   The angle of the axes between a crown gear and fully-engaged bevel pinion must therefore be greater than 90 degrees, since the pinion must have some pitch cone angle greater than zero and less than 90 degrees  (well, two crown gears can mesh, but that hardly deserves the name "gearing"; it's a clutch.
Hypoid gearing is different from all the above, industrially important, and may be worth mentioning; it's generally what's used in motor vehicle differentials IIRC.  I don't have an authoritative reference defining the type.
Oops... originally didn't know how to "sign".  129.230.241.5 22:55, 4 October 2006 (UTC)
thread_title:  Page contains errors of varying degees of obscurity 

message: It would be nice to see a section on the history of gear wheels.  This New York Times articlementions that
* a geared computing device existed in the 2nd century B.C.
* According to Dr. François Charette of the University of Munich museum, "It seems clear [that] much of the mind-boggling technological sophistication available in some parts of the Hellenistic and Greco-Roman world was simply not transmitted further... The gear-wheel, in this case, had to be reinvented."
I came to Wikipedia to determine when, prior to such discoveries as this, the gear had been considered to have been invented.  But no info in this article.  Wareh 21:44, 29 November 2006 (UTC)
replies: text: Well, if anyone wants to work on this, see the response at Wikipedia:Reference desk/Archives/Science/2006 November 29#History_of_Gears, and possibly consider such objects as Antikythera mechanism (the one in the Times article I linked), South Pointing Chariot, watermills and Salisbury cathedral clock.  Wareh 01:20, 1 December 2006 (UTC)
replies: text: I came to the article to find out when gears were first invented, so I noticed a history section missing too. pgr94 (talk) 16:08, 12 November 2009 (UTC)
replies: text:  OK, we now have a brief "History" section that briefly mentions all the items Wareh listed. But I suspect that is only the very beginning of the historic things that could be mentioned here. --DavidCary (talk) 18:44, 21 August 2014 (UTC)
thread_title:  History of Gears 

message: This edit:
* http://en.wikipedia.org/w/index.php?title=Gear&diff=104901698&oldid=104581113
contained some good data, albeit badly formatted. As time permits, we should take that data and incorporate it into the article. Or perhaps our anonymous editor will try again for us?
Atlant 13:39, 2 February 2007 (UTC)
thread_title:  An edit that had some good data 

message: Stated in the article is 1 rpm = 120π rad/s. I think this is in error?
:Actually, 1 rpm = π/30 rad/s. 120π = 3600 rpm.
its true  — Preceding unsigned comment added by 116.202.42.205 (talk) 13:45, 5 December 2011 (UTC)
thread_title:  1 rpm = 1/30π rad/s? 

message: Definitely not. They should obviously be in something like a "Power Transmission" category but apart from being round sprockets and gears are totally distinct: different tooth form, different direction of driven wheel, different ways of accomodating increased loading etc. MarkMLl 16:30, 14 September 2007 (UTC)
thread_title: Suggested merge of "Sprocket" into "Gear" article

message: Tooth contact nomenclature is currently split between this article and a host of other articles listed at List of gear nomenclature. I think these need to be merged. Biscuittin (talk) 13:20, 3 January 2008 (UTC)
replies: text: I noticed that too, but I'm not very keen on the idea of merging more content into Gear because Gear is already such a very long article. I was wondering whether some content in Gear could be partly or wholly split off into other articles. The section on nomenclature is very long and rather breaks up the flow of the article; it could be split off and merged into List of gear nomenclature, or else transwikied to wikibooks per WP:NOT#GUIDE. - Neparis (talk) 04:35, 5 January 2008 (UTC)
replies: text: I think this page should be made more simple and more easy to read.  —Preceding unsigned comment added by 86.143.119.109 (talk) 17:07, 16 October 2008 (UTC)
replies: text:  I recently merged all of the stub articles referenced by list of gear nomenclature into that article. After seeing that most of that info is repeated here, I'm going to attempt to merge the info here into that article as well. This article is currently 52 Kb, so it definitely needs a trimming. Wizard191 (talk) 18:56, 29 December 2008 (UTC)
replies: text:  The section has been organized as described here for over a year.  I think it is OK to now remove the tag from the article section.  OK? Heathhunnicutt (talk) 16:42, 19 January 2010 (UTC)
replies: text: What tag? (I'm probably just blind.) Wizard191 (talk) 17:19, 19 January 2010 (UTC)
replies: text: The one I just removed, which had appeared under "Double Helical" in November of 2009.  I found no matching talk on this page, and wrongly assumed this subsection was talk on the subject of that tag.  I removed the tag because it was undiscussed for several months.  The OP can replace it and talk about it if they desire. :) Heathhunnicutt (talk) 03:15, 21 January 2010 (UTC)

text: I agree that a significant portion of the detail in the Nomenclature section should be split and merged into List of gear nomenclature (though, perhaps, that should be renamed simply to "Gear Nomenclature") Pscyking (talk) 12:16, 24 September 2016 (UTC)

text:  The article List of gear nomenclature is nice but not what U R looking for if U need the terminus technicus for a special feature. The graphic in this article is quite more helpful. Leave it hear or rework the mentioned list for readability. If nobody does soon, I'm in favour of removing the tag. Horst Emscher (talk) 11:27, 30 September 2015 (UTC)
thread_title:  Nomenclature 

message: A suggestion for an additional term: backdrivable.
A transmission is backdrivable if a force or torque on its output can move its input. An example of a backdrivable transmission is an automotive steering mechanism: when rock climbing in a 4WD vehicle, you should keep your thumbs on the outside of the steering wheel, because lateral torques on the front wheels can violently spin the steering wheel. An example of a non-backdrivable transmission is a machine head on a stringed musical instrument; although the worm can be turned to drive the worm wheel and tighten the strings, the enormous force on the worm wheel is unable to cause the worm to spin.
I'm not sure where to work this in, though, without adding a whole new section, and the article is pretty piecemeal as-is. Perhaps the article could use some reorganization, collecting terms together into an "Other terms" section? --Dan Griscom (talk) 12:22, 24 February 2008 (UTC)
thread_title:  Add a useful term: "backdrivable" 

message: Would it be possible for a definition of normal and circular module?  Normal module is referred to in the profile shift and rack shift, but not actually defined.  Also, looking at the equation for Diametral Pitch (transverse), it appears that module (m) is used (i.e. PD = 25.4/m), but again, not defined. As the module can be used for calculating the pitch diameter (i.e. D=number of teeth x module), I would have thought the inclusion of the module was fundemental to an article on gears.  I'm currently scouring the text books on my desk for a definition (no luck so far), but if anyone else has a definition, could they please post it? Thanks! StephenBuxton (talk) 09:31, 20 May 2008 (UTC)
replies: text: Found one from the Machinery's Handbook 26th Edition.  I've also added a section about the module.  Feel free to expand! StephenBuxton (talk) 16:15, 20 May 2008 (UTC)
thread_title:  Definition of Module 

message: I think some discussion of transmission efficiency would contribute to this article. A basic definition of gear efficiency as the output torque divided by the product of input torque and gear ratio would be good. The only mention of efficiency is in reference to worm gears, and little is stated by comparison about the others. A list of different types of gearing and approximate efficiency ranges would also be very useful. Such a list may be difficult to find or compile, however.  Barjeconiah (talk) 06:06, 28 March 2009 (UTC)
thread_title:  Discussion of Gearing efficiencies? 

message: The definition list uses the term "tooth space" but never defines it. -Craig Pemberton (talk) 22:58, 9 November 2009 (UTC)
replies: text: I have removed both instances of this term. Wizard191 (talk) 23:13, 9 November 2009 (UTC)
replies: text: I think the same may be true of "operating addendum". Either way it's a bit confusing to me, a layman. -Craig Pemberton (talk) 04:51, 10 November 2009 (UTC)

text: Also "datum circle" and some of the terms repeat. -Craig Pemberton (talk) 06:31, 10 November 2009 (UTC)
replies: text: Yes these need to be taken care of, however I feel that all but the general nomenclature section be merged with the list of gear nomenclature article. For more info on this see the #Tooth contact nomenclature section above. Wizard191 (talk) 19:31, 10 November 2009 (UTC)

text: I have linked the datum terminology, but I can't find a definition for "operating addendum". I've found a few books that use the term, but don't define it, however it appears to be different from just an "addendum". Wizard191 (talk) 21:06, 10 November 2009 (UTC)
thread_title:  Tooth space 

message: In the begining it says something about gears meshing with a non-rotating rack and provides translation, but the link takes you to the begining of a page about traslation but not in terms of motion but in terms of language with a picture of the rosetta stone. I think this link needs to be fixed.  —Preceding unsigned comment added by 69.136.72.16 (talk) 20:36, 19 January 2010 (UTC)
replies: text: I've fixed the link. Thanks for pointing it out. Wizard191 (talk) 21:14, 19 January 2010 (UTC)
thread_title:  Translation 

message: I see no section on the hyperbolic gear. Granted, its practical use is VERY limited, and I do not have a free-source image to contribute, but I feel that it merits mention on this page. 97.102.228.89 (talk) 00:55, 3 August 2010 (UTC)
replies: text: Are you referring to a hypoid gear? Wizard191 (talk) 12:15, 3 August 2010 (UTC)
thread_title:  Hyperbolic Gear 

message: In the first image, the speed of the smaller gear is not constant.  Is this a program issue or is this right ?
--AXRL (talk) 12:07, 8 May 2012 (UTC)
thread_title:  Image nb 1 

message: 550AD (quite a gap)
http://objectwiki.sciencemuseum.org.uk/wiki/Byzantine_sundial_calendar.html
May be worth a mention.Geni (talk) 23:08, 5 August 2013 (UTC)
thread_title: Second oldest gear found

message: there is no History section. Some history of this technology would be interesting.  — Preceding unsigned comment added by 69.149.65.53 (talk) 03:46, 28 October 2013 (UTC)
replies: text: Yes. A History section has been added to this article. See also Talk:Gear#History_of_Gears. --DavidCary (talk) 03:28, 24 August 2014 (UTC)
thread_title:  History? 

message: Is there any difference between these terms? The article did not really make that clear. 88.104.249.73 (talk) 20:36, 17 February 2014 (UTC)
thread_title:  Difference between 'gear', 'cog' and 'cogwheel'. 

message: The pictures of the pair of brass meccano gears in the Helical section is misleading, I think.
Although shown meshing in crossed configuration, in the parallel configuration the pair of gears are not suitable for meshing as one of them needs to have the opposite handedness. Displaying them as here gives the misleading impression that same-handedness will work in the parallel configuration. Gwideman (talk) 00:39, 15 July 2014 (UTC)
replies: text: I agree that the parallel configuration shown would not allow meshing for the reason you have explained. However, it is a relatively minor problem that only the eagle-eyed reader would detect (and I'm not one of them.) Wikimedia Commons has a small number of photographs in its category on helical gears but none of them is superior to the one we have here. See Category:Helical gears. Dolphin (t) 01:17, 15 July 2014 (UTC)

text: Well it is definitely misleading and embarrassing. Just spent 2 minutes trying to make sense out of it before realizing there's none. Salmin (talk) 22:56, 10 February 2020 (UTC)
thread_title:  Helical gear picture is misleading 

message: Should there be a section here on the 'biological gears' that were discovered in 2013?  Or at least a link to some other appropriate page ("Biological Nano-machines" or something of the like?) if it exists.
(refs: ) Jimw338 (talk) 16:10, 8 February 2015 (UTC)
replies: text: Already there. Gear#Gear mechanism in natural world Andy Dingley (talk) 21:28, 8 February 2015 (UTC)
thread_title:  Should include 'Biological Gear' finding (2013)? Or reference to appropriate article 

message: An editor has asked for a discussion to address the redirect Gearing. Please participate in the redirect discussion if you have not already done so.  -- 65.94.43.89 (talk) 21:16, 21 March 2015 (UTC)
thread_title:  Gearing listed at [[Wikipedia:Redirects for discussion|Redirects for discussion]] 

message: "The earliest gears in Europe were circa CE 50 by Hero of Alexandria,[4] but they can be traced back to the Greek mechanics of the Alexandrian school in the 3rd century BCE and were greatly developed by the Greek polymath Archimedes (287–212 BCE).[5] The Antikythera mechanism is an example of a very early and intricate geared device, designed to calculate astronomical positions. Its time of construction is now estimated between 150 and 100 BCE.[6]"
If the earliest were circa 50, how can Archimedes have worked on them 3 centuries earlier? It can't even be "earliest known gears" because the Antikythera device is (as mentioned) much older than that. What was this supposed to say?
IAmNitpicking (talk) 15:58, 29 May 2015 (UTC)
thread_title:  Dating of early gears: contradictory text 

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thread_title:  External links modified 

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thread_title:  External links modified 

message: The 25 "standard values for modules" listed in this Gear article almost exactly match the "more rounded" R″10 series described in the Renard series article.
However, there are a few exceptions.
Is there some technical reason for those exceptions, that make those "standard gear" values (1.25 mm, 32 mm, etc.) work better than more-rounded Renard series ( R″10 ) values (1.2 mm, 30 mm, etc.) or the unrounded Renard series (R10) values (1.25 mm, 31.5 mm) ?
Or is there no particular technical reason, and those particular values are frozen historical accidents?
--DavidCary (talk) 18:26, 22 July 2019 (UTC)
thread_title:  standard values of modules 

message: The image given here : https://en.wikipedia.org/wiki/Gear#General_nomenclature doesn't consider the term known as fillet radius. It doesn't show any curvature in the fillet region - i think that curvature which provides a small gap between the gears is important for the gear stresses to be elevated. So probably the image can be changed to one like these: https://player.slideplayer.com/80/13400230/slides/slide_17.jpg , https://player.slideplayer.com/80/13400230/slides/slide_16.jpg. 
Mr.Mog (talk) 11:12, 27 October 2019 (UTC)
thread_title:  image of spur gear in the general nomenclature section (under nomenclature) not accurate enough 

message: mmm...we're going to have to broaden the context in-light-of new information: Johnfreez (talk) 10:51, 18 February 2021 (UTC)
replies: text: oops...this has already been pointed-out in another section of this talk-page..but perhaps there ought to be a mention of naturally evolved gears in the article introduction? Johnfreez (talk) 11:00, 18 February 2021 (UTC)
thread_title:  “first observation of mechanical gearing in a biological structure” 

message: Could be the gear bearing article be included in the list of types? There are already two similar gear arrangements: "rack and pinion"; and, "epicyclic gear". George Rodney Maruri Game (talk) 01:54, 5 July 2022 (UTC)
thread_title:  Gear bearing article