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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)
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
Gregorydavid 07:52, 16 May 2006 (UTC) fgffffffffffffffffffffffffffffffff — Preceding unsigned comment added by 203.76.140.121 ( talk) 07:05, 2 May 2013 (UTC)
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)
I took some photographs of gears from a Meccano construction set to make these images. Arthur Clarke 17:48, 31 July 2006 (UTC)
This image is exactly the same as one in an ad for gear made by David Brown and Sons Ltd that appears in "Sketches of Engine and Machine Details" by Wallace Bentley in the 6th ed of 1916. 89.195.207.33 ( talk) 10:13, 24 June 2010 (UTC)
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)
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)
It would be nice to see a section on the history of gear wheels. This New York Times articlementions that
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)
Removed subhead, "History of the differential gear", keeping the content. Differentials are never discussed on this page, so their history as separate from gears in general is not pertinent. Also, most of the items discussed were not actually differentials! I also removed some minor text which were verbatim quotes from the source. I did add a See Also for Differential, as they are way cool. ChrisMiddleton ( talk) 22:37, 11 September 2015 (UTC)
The article currently contains the following statement:
While this is true probably 99-44/100% of the time, this isn't always true. I once saw a mechanism that drove a very-high-pitch worm in order to achieve a very large speed step-up ratio in a single gear pair. I can't remember exactly what was being driven; it might have been a flyball governor.
Unless somebody has a citation, we probably shouldn't edit the article, but I thought I'd note this for the record here ion the talk page.
Atlant 17:03, 5 December 2006 (UTC)
I was wondering if someone could put up a definition of a cog. I always knew it was gear related, but not exactly what it is. Fresheneesz 02:01, 11 January 2007 (UTC)
This edit:
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)
'gears' are round mechanical objects often called toothed wheels, cogged wheels or cogs. a gear has teeth round its edge. these are what link with other cogs to form a rotational motion. the teeth can be called cogs too.
Stated in the article is 1 rpm = 120π rad/s. I think this is in error?
its true — Preceding unsigned comment added by 116.202.42.205 ( talk) 13:45, 5 December 2011 (UTC)
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)
There should be a paragraph which briefly describes the manufacturing of gears, and the machines used for this process.
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)
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)
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)
See definitions under
General nomenclature. This sentence does not make sense:
Module
"A scaling factor used in metric gears with units in millimeters who's effect is to enlarge the gear tooth size as the module increases and reduce the size as the module decreases" —Preceding
unsigned comment added by
129.78.64.105 (
talk)
05:17, 24 August 2010 (UTC)
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)
The definition list uses the term "tooth space" but never defines it. - Craig Pemberton ( talk) 22:58, 9 November 2009 (UTC)
The article speaks of a "gear model" without defining it. What exactly is a gear model? pgr94 ( talk) 21:06, 4 December 2009 (UTC)
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)
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)
How about someone do some mathsy physicsy stuff? Like, talk about the effect that gear pairs have on (rotational) speed, power, torque etc. Would, do you think, would it be OK if I tried writing something? 210.55.20.219 ( talk) 21:31, 16 February 2011 (UTC) Eric
This may seem a bit trivial, but the restriction on the angle between shafts of two bevel gears seems a bit arbitrary; surely an angle of zero degrees would simply be a coupling, while 180 would be a spur gear. While these might not be bevel gears per se, there isn't any inherent restriction (?) 80.229.172.13 ( talk) 20:46, 14 February 2012 (UTC)
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)
Like in computer software, for settings and preferences. Let's add that! But where and how? If it's already there, pls disregard. Anna Frodesiak ( talk) 05:43, 3 January 2013 (UTC)
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)
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)
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)
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)
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:
"Functioning 'mechanical gears' seen in nature for the first time; Sep 12, 2013". Phys.org. Retrieved 8 February 2015.Burrows, M.; Sutton, G. (12 September 2013). "Interacting Gears Synchronize Propulsive Leg Movements in a Jumping Insect". Science. 341 (6151): 1254–1256.
doi:
10.1126/science.1240284. {{
cite journal}}
: |access-date=
requires |url=
(
help))
Jimw338 (
talk)
16:10, 8 February 2015 (UTC)
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)
What a wonderful page! Great photos as well. This includes all things gears and has greatly increased my knowledge of gears. Thanks to everyone who has contributed to this page. — Preceding unsigned comment added by 61.69.24.118 ( talk • contribs) 04:14, 18 April 2015
"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)
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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)
The image given here : /info/en/?search=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)
mmm...we're going to have to broaden the context in-light-of new information: Johnfreez ( talk) 10:51, 18 February 2021 (UTC)
Previously believed to be only man-made, a natural example of a functioning gear mechanism has been discovered in a common insect - showing that evolution developed interlocking cogs long before we did. In Issus, the skeleton is used to solve a complex problem that the brain and nervous system can’t Malcolm Burrows The juvenile Issus - a plant-hopping insect found in gardens across Europe - has hind-leg joints with curved cog-like strips of opposing ‘teeth’ that intermesh, rotating like mechanical gears to synchronise the animal’s legs when it launches into a jump. The finding demonstrates that gear mechanisms previously thought to be solely man-made have an evolutionary precedent. Scientists say this is the “first observation of mechanical gearing in a biological structure” [1]
References
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)
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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)
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
Gregorydavid 07:52, 16 May 2006 (UTC) fgffffffffffffffffffffffffffffffff — Preceding unsigned comment added by 203.76.140.121 ( talk) 07:05, 2 May 2013 (UTC)
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)
I took some photographs of gears from a Meccano construction set to make these images. Arthur Clarke 17:48, 31 July 2006 (UTC)
This image is exactly the same as one in an ad for gear made by David Brown and Sons Ltd that appears in "Sketches of Engine and Machine Details" by Wallace Bentley in the 6th ed of 1916. 89.195.207.33 ( talk) 10:13, 24 June 2010 (UTC)
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)
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)
It would be nice to see a section on the history of gear wheels. This New York Times articlementions that
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)
Removed subhead, "History of the differential gear", keeping the content. Differentials are never discussed on this page, so their history as separate from gears in general is not pertinent. Also, most of the items discussed were not actually differentials! I also removed some minor text which were verbatim quotes from the source. I did add a See Also for Differential, as they are way cool. ChrisMiddleton ( talk) 22:37, 11 September 2015 (UTC)
The article currently contains the following statement:
While this is true probably 99-44/100% of the time, this isn't always true. I once saw a mechanism that drove a very-high-pitch worm in order to achieve a very large speed step-up ratio in a single gear pair. I can't remember exactly what was being driven; it might have been a flyball governor.
Unless somebody has a citation, we probably shouldn't edit the article, but I thought I'd note this for the record here ion the talk page.
Atlant 17:03, 5 December 2006 (UTC)
I was wondering if someone could put up a definition of a cog. I always knew it was gear related, but not exactly what it is. Fresheneesz 02:01, 11 January 2007 (UTC)
This edit:
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)
'gears' are round mechanical objects often called toothed wheels, cogged wheels or cogs. a gear has teeth round its edge. these are what link with other cogs to form a rotational motion. the teeth can be called cogs too.
Stated in the article is 1 rpm = 120π rad/s. I think this is in error?
its true — Preceding unsigned comment added by 116.202.42.205 ( talk) 13:45, 5 December 2011 (UTC)
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)
There should be a paragraph which briefly describes the manufacturing of gears, and the machines used for this process.
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)
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)
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)
See definitions under
General nomenclature. This sentence does not make sense:
Module
"A scaling factor used in metric gears with units in millimeters who's effect is to enlarge the gear tooth size as the module increases and reduce the size as the module decreases" —Preceding
unsigned comment added by
129.78.64.105 (
talk)
05:17, 24 August 2010 (UTC)
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)
The definition list uses the term "tooth space" but never defines it. - Craig Pemberton ( talk) 22:58, 9 November 2009 (UTC)
The article speaks of a "gear model" without defining it. What exactly is a gear model? pgr94 ( talk) 21:06, 4 December 2009 (UTC)
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)
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)
How about someone do some mathsy physicsy stuff? Like, talk about the effect that gear pairs have on (rotational) speed, power, torque etc. Would, do you think, would it be OK if I tried writing something? 210.55.20.219 ( talk) 21:31, 16 February 2011 (UTC) Eric
This may seem a bit trivial, but the restriction on the angle between shafts of two bevel gears seems a bit arbitrary; surely an angle of zero degrees would simply be a coupling, while 180 would be a spur gear. While these might not be bevel gears per se, there isn't any inherent restriction (?) 80.229.172.13 ( talk) 20:46, 14 February 2012 (UTC)
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)
Like in computer software, for settings and preferences. Let's add that! But where and how? If it's already there, pls disregard. Anna Frodesiak ( talk) 05:43, 3 January 2013 (UTC)
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)
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)
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)
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)
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:
"Functioning 'mechanical gears' seen in nature for the first time; Sep 12, 2013". Phys.org. Retrieved 8 February 2015.Burrows, M.; Sutton, G. (12 September 2013). "Interacting Gears Synchronize Propulsive Leg Movements in a Jumping Insect". Science. 341 (6151): 1254–1256.
doi:
10.1126/science.1240284. {{
cite journal}}
: |access-date=
requires |url=
(
help))
Jimw338 (
talk)
16:10, 8 February 2015 (UTC)
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)
What a wonderful page! Great photos as well. This includes all things gears and has greatly increased my knowledge of gears. Thanks to everyone who has contributed to this page. — Preceding unsigned comment added by 61.69.24.118 ( talk • contribs) 04:14, 18 April 2015
"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)
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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)
The image given here : /info/en/?search=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)
mmm...we're going to have to broaden the context in-light-of new information: Johnfreez ( talk) 10:51, 18 February 2021 (UTC)
Previously believed to be only man-made, a natural example of a functioning gear mechanism has been discovered in a common insect - showing that evolution developed interlocking cogs long before we did. In Issus, the skeleton is used to solve a complex problem that the brain and nervous system can’t Malcolm Burrows The juvenile Issus - a plant-hopping insect found in gardens across Europe - has hind-leg joints with curved cog-like strips of opposing ‘teeth’ that intermesh, rotating like mechanical gears to synchronise the animal’s legs when it launches into a jump. The finding demonstrates that gear mechanisms previously thought to be solely man-made have an evolutionary precedent. Scientists say this is the “first observation of mechanical gearing in a biological structure” [1]
References
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)