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They roll. Alot.
[[Image:Chain.gif|frame|right|Roller chain and [[sprocket]]]]
[[Image:The sketch (drawing) of roller chain, Leonardo da Vinci.jpg|thumb|250px|The [[sketch (drawing)|sketch]] of roller chain, [[Leonardo da Vinci]]]]

'''Roller chain''' or '''bush roller chain''' is the type of [[chain drive]] most commonly used for transmission of [[power transmission#Mechanical power|mechanical power]] on many kinds of domestic, industrial and agricultural machinery, including [[conveyor]]s, [[wire]] and [[tube]] [[drawing]] machines, [[printing press]]es, [[car]]s, [[motorcycle]]s, and simple machines like [[bicycle]]s. It consists of a series of short cylindrical rollers held together by side links. It is driven by a toothed wheel called a [[sprocket]]. It is a simple, reliable, and efficient<ref>As much as 98% efficient under ideal conditions, according to {{cite web | last = Kidd | first = Matt D. | coauthors = N. E. Loch, R. L. Reuben | year = 1998 | url = http://www.hw.ac.uk/mecWWW/research/mdk/res.htm | title = Bicycle Chain Efficiency | work = The Engineering of Sport conference | publisher = Heriot Watt University | accessdate = 2006-05-16 |archiveurl = http://web.archive.org/web/20060206210227/http://www.hw.ac.uk/mecWWW/research/mdk/res.htm <!-- Bot retrieved archive --> |archivedate = 2006-02-06}}</ref> means of power transmission.

Though [[Hans Renold]] is credited with inventing roller chain in 1880, sketches by [[Leonardo da Vinci]] in the 16th century show a chain with a [[rolling-element bearing#Roller bearings|roller bearing]].<ref>In the 16th century, [[Leonardo da Vinci]] made sketches of what appears to be the first steel chain. These chains were probably designed to transmit pulling, not wrapping, power because they consist only of plates and pins and have metal fittings. However, da Vinci's sketch does show a roller bearing.{{cite book | title=The Complete Guide to Chain | editor=[[Tsubakimoto Chain Co.]] | publisher=Kogyo Chosaki Publishing Co., Ltd. | isbn=0-9658932-0-0 | year=1997 | pages=240 | id=p. 211 | url=http://chain-guide.com/breaks/brief-history-of-chain.html | accessdate = 2006-05-17}}</ref>

==Construction of the chain==
[[Image:Kettenvergleich.jpg|thumb|upright=1.5|Two different sizes of roller chain, showing construction.]]

There are actually two types of [[link (chain)|link]]s alternating in the [[bushing (bearing)|bush]] roller chain. The first type is inner links, having two inner plates held together by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the outer links, consisting of two outer plates held together by pins passing through the bushings of the inner links. The "bushingless" roller chain is similar in operation though not in construction; instead of separate bushings or sleeves holding the inner plates together, the plate has a tube stamped into it protruding from the hole which serves the same purpose. This has the advantage of removing one step in assembly of the chain.

The roller chain design reduces friction compared to simpler designs, resulting in higher efficiency and less wear. The original power transmission chain varieties lacked rollers and bushings, with both the inner and outer plates held by pins which directly contacted the [[sprocket]] teeth; however this configuration exhibited extremely rapid wear of both the sprocket teeth, and the plates where they pivoted on the pins. This problem was partially solved by the development of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the wear over a greater area; however the teeth of the sprockets still wore more rapidly than is desirable, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and provided rolling contact with the teeth of the sprockets resulting in excellent resistance to wear of both sprockets and chain as well. There is even very low friction, as long as the chain is sufficiently lubricated. Continuous, clean, lubrication of roller chains is of primary importance for efficient operation.{{Citation needed|date=January 2010}}

==Lubrication==
The great majority of driving chains operate in clean environments, the wearing surfaces (ie the pins and the bushings) safe from precipitation and air-born grit, many even in a sealed environment such as an oil bath.

A few other chains run unprotected and in those cases, internally sealed roller chain manufacturers such as [[Tsubakimoto Chain Co.|Tsubaki]], Diamond, Morse, Renold, and Rexnord produce low-maintenance versions wherein [[o-ring]]s or x-rings seal in the lubricant for life.

However, there are a few chains that have to operate in dirty conditions, and for size or operational reasons cannot be sealed. One example is the bicycle chain drive on a derailleur equipped bicycle (though cheaper hub-gear bicycles may be similarly naked to the elements). These chains will necessarily have relatively high rates of wear, particularly when the operators are prepared to accept more friction, less efficiency, more noise and more frequent replacement as they neglect lubrication and adjustment.

===Motorcycle chain lubrication===

Chains operating at high speeds comparable to those on motorcycles should be used in conjunction with an oil bath<ref>Chains operating at high speeds comparable to those on motorcycles should be used in conjunction with an oil bath, according to: Lubrecht, A. and Dalmaz, G., (eds.) Transients Processes in Tribology, Proc 30th Leeds-Lyon Symposium on Tribology. 30th Leeds-Lyon Symposium on Tribology, 2 - 5 September 2003, Lyon. Tribology and Interface Engineering Series (43). Elsevier , Amsterdam, pp. 291-298.}</ref>. For modern motorcycles this is not applicable and most motorcycle chains run unprotected. They are subject to extreme forces and have to operate in tough conditions being exposed to rain, dirt, sand and road salt.

Motorcycle chains are part of the drive train to transmit the motor power to the back wheel. While properly lubricated chains can reach an efficiency of more 98% in the transmission, unlubricated chains will significantly decrease performance and increase chain and sprockets wear<ref>As much as 98% efficient under ideal conditions, according to {{cite web | last = Kidd | first = Matt D. | coauthors = N. E. Loch, R. L. Reuben | year = 1998 | url = http://www.hw.ac.uk/mecWWW/research/mdk/res.htm | title = Bicycle Chain Efficiency | work = The Engineering of Sport conference | publisher = Heriot Watt University | accessdate = 2006-05-16 |archiveurl = http://web.archive.org/web/20060206210227/http://www.hw.ac.uk/mecWWW/research/mdk/res.htm <!-- Bot retrieved archive --> |archivedate = 2006-02-06}}</ref>.

Two distinct types of aftermarket lubricants are available for motorcycle chains, spray on lubricants and oil drip feed systems.
*Spray lubricants may contain wax or PTFE. Whilst these lubricants use tack additives to stay on the chain they can also attract dirt and sand from the road and over time produce a grinding paste that accelerates component wear.
*Oil drip feed systems continuously lubricate the chain and use light oil that does not stick to the chain. Research has shown that oil drip feed systems provide the greatest wear protection and greatest power saving <ref>Oil drip feed provided the greatest wear protection between chain roller and pin, Oil drip feed provided the greatest power saving over unlubricated chains and sprockets, according to Lee, P.M. and Priest, M. (2004) An innovation integrated approach to testing motorcycle drive chain lubricants. In: Lubrecht, A. and Dalmaz, G., (eds.) Transients Processes in Tribology, Proc 30th Leeds-Lyon Symposium on Tribology. 30th Leeds-Lyon Symposium on Tribology, 2 - 5 September 2003, Lyon. Tribology and Interface Engineering Series (43). Elsevier , Amsterdam, pp. 291-298.</ref>.

====Scottoiler====
'''Oil drip feed systems''' or '''automatic motorcycle chain oilers''' are often referred to as ‘Scottoilers’. Scottoiler Ltd.<ref name="Scottoiler">{{Citation |title=Scottoiler Ltd. |url=http://www.scottoiler.com/ |accessdate=2011-01-13 |postscript=.}}.</ref> is a manufacturer of automatic oil drip feed systems for motorbikes.<ref name="Motorcycle_Trader_2010-04">{{Citation |title=Bucking the Trend: Scottoiler |journal=Motorcycle Trader |year=2010 |month=April |pp=17-19 |postscript=.}}</ref> The original product is based on a vacuum system and works by gravity feed. The engine vacuum provides the power to open a valve. The oil then siphons from the reservoir by gravity and the flow rate can be adjusted by a dial opening/closing the valve aperture.<ref>Scottoiler Scotland Ltd. (2010) How it works? Available from: http://www.scottoiler.com/uk/how-it-works/vsystem.html </ref>

Especially in the UK the brand is on the way to become a [[genericized trademark]].

==Variants in design==
If the chain is not being used for a high wear application (for instance if it is just transmitting motion from a hand operated lever to a control shaft on a machine, or a sliding door on an oven), then one of the simpler types of chain may still be used. Conversely, where extra strength but the smooth drive of a smaller pitch is required, the chain may be "siamesed"; instead of just two rows of plates on the outer sides of the chain, there may be three ("duplex"), four ("triplex"), or more rows of plates running parallel, with bushings and rollers between each adjacent pair, and the same number of rows of teeth running in parallel on the sprockets to match. Timing chains on automotive engines, for example, typically have multiple rows of plates called strands.

Roller chain is made in several sizes, the most common [[American National Standards Institute]] (ANSI) standards being 40, 50, 60, and 80. The first digit(s) indicate the pitch of the chain in eighths of an [[inch]], with the last digit being 0 for standard chain, 1 for lightweight chain, and 5 for bushed chain with no rollers. Thus, a bicycle chain with half inch pitch would be a #40 while a #160 sprocket would have teeth spaced 2 inches apart, etc. Metric pitches are expressed in sixteenths of an inch; thus a metric #8 chain (08B-1) would be equivalent to an ANSI #40. Most roller chain is made from plain carbon or alloy steel, but stainless steel is used in food processing machinery or other places where lubrication is a problem, and nylon or brass are occasionally seen for the same reason.

Roller chain is ordinarily hooked up using a master link (also known as a connecting link), which typically has one pin held by a [[horseshoe clip]] rather than friction fit, allowing it to be inserted or removed with simple tools. Half links (also known as offsets) are available and are used to increase the length of the chain by a single roller.

==Use==
* Roller chains are used in low- to mid-speed drives at around 600 to 800 feet per minute; however, at higher speeds, around 2,000 to 3,000 feet per minute, [[belt (mechanical)|V-belt]]s are normally used due to wear and noise issues.

* A [[bicycle chain]] is a form of roller chain. Bicycle chains may have a master link, or may require a [[chain tool]] for removal and installation. A similar but larger and thus stronger chain is used on most [[motorcycle]]s although it is sometimes replaced by either a [[toothed belt]] or a [[shaft drive]], which offer lower noise level and fewer maintenance requirements.

* In older [[automobile]] [[engine]]s from the [[United States]] and other countries, roller chains would traditionally drive the [[camshaft]](s) off the [[crankshaft]], generating less noise than a [[gear]] drive as used in very high performance engines, and offering more durability than the [[timing belt]] frequently used on more modern engines. Many modern automobile engines still use roller chains, which are more durable than timing belts.

* Chains are also used in [[forklift]]s using hydraulic rams as a pulley to raise and lower the carriage; however, these chains are not considered roller chains, but are classified as lift or [[leaf chain]]s.

* [[Chainsaw]] [[saw chain|cutting chains]] superficially resemble roller chains but are more closely related to leaf chains. They are driven by projecting drive links which also serve to locate the chain onto the bar.

[[Image:Vector-nozzle-sea-harrier-jet-common.jpg|thumb|[[Sea Harrier]] FA.2 ''[[Serial number|ZA195]]'' front (cold) vector thrust nozzle - the nozzle is rotated by a chain drive from an air motor]]

*A perhaps unusual use of a pair of motorcycle chains is in the [[Harrier Jump Jet]], where a chain drive from an air motor is used to rotate the movable engine nozzles, allowing them to be pointed downwards for hovering flight, or to the the rear for normal forward flight, a system known as [[Thrust vectoring]].

==Wear==
The effect of wear on a roller chain is to increase the pitch (spacing of the links), causing the chain to grow longer. Note that this is due to wear at the pivoting pins and bushes, not from actual stretching of the metal (as does happen to some flexible steel components such as the hand-brake cable of a motor vehicle).

With modern chains it is unusual for a chain (other than that of a bicycle) to wear until it breaks, since a worn chain leads to the rapid onset of wear on the teeth of the sprockets, with ultimate failure being the loss of all the teeth on the sprocket. The sprockets (in particular the larger of the two) suffer a grinding motion that puts a characteristic hook shape into the driven face of the teeth. (This effect is made worse by a chain improperly tensioned, but is unavoidable no matter what care is taken). The worn teeth (and chain) no longer provides smooth transmission of power and this may become evident from the noise, the vibration or (in car engines using a timing chain) the variation in ignition timing seen with a [[timing light]]. Both sprockets and chain should be replaced in these cases, since a new chain on worn sprockets will not last long. However, in less severe cases it may be possible to save the smaller of the two sprockets, since it is always the larger one that suffers the most wear. Only in very light-weight applications such as a bicycle, or in extreme cases of improper tension, will the chain normally jump off the sprockets.

The lengthening due to wear of a chain is calculated by the following formula:

<math>%=((M-(S*P))/(S*P))*100</math>

M = the length of a number of links measured

S = the number of links measured

P = Pitch

In industry, it is usual to monitor the movement of the chain tensioner (whether manual or automatic) or the exact length of a drive chain (one rule of thumb is to replace a roller chain which has elongated 3% on an adjustable drive or 1.5% on a fixed-center drive). A simpler method, particularly suitable for the cycle or motorcycle user, is to attempt to pull the chain away from the larger of the two sprockets. Any significant movement (eg making it possible to see through a gap) probably indicates a chain worn up to and beyond the limit. Sprocket damage will result if the problem is ignored.
===Bicycle chain wear===
The lightweight chain of a bicycle with [[derailleur gears]] can snap (or rather, come apart at the side-plates, since it is normal for the riveting to fail first) because the wearing pins inside are not parallel, they are barrel-shaped. Contact between the pin and the bush is not the regular line, but a point. This form of construction is necessary because the gear-changing action of this form of transmission requires the chain to both bend sideways and to twist.

Chain failure is much less of a problem on hub-geared systems (often known as "Sturmey Archer") since the parallel pins have a much bigger wearing surface in contact with the bush. The hub-gear system also allows complete enclosure, a great aid to lubrication and protection from grit.

==Chain strength==
The most common measure of roller chain's strength is [[tensile strength]]. Tensile strength represents how much load a chain can withstand under a one-time load before breaking. Just as important as tensile strength is a chain's fatigue strength. The critical factors in a chain's fatigue strength is the quality of steel used to manufacture the chain, the heat treatment of the chain components, the quality of the pitch hole fabrication of the linkplates, and the type of shot plus the intensity of shot peen coverage on the linkplates. Other factors can include the thickness of the linkplates and the design (contour) of the linkplates. The rule of thumb for roller chain operating on a continuous drive is for the chain load to not exceed a mere 1/6 or 1/9 of the chain's tensile strength, depending on the type of master links used (press-fit vs. slip-fit){{Citation needed|date=March 2010}}. Roller chains operating on a continuous drive beyond these thresholds can and typically do fail prematurely via linkplate fatigue failure.

The standard minimum ultimate strength of the ANSI 29.1 steel chain is 12,500 x (pitch, in inches)<sup>2</sup> (pitch squared x 12,500).<ref>[http://www.beijingthc.com/transmission_drive_chain/ansi_roller_chains.htm]</ref>

==Chain standards==
[[Standards organization]]s (such as [[ANSI]]) maintain standards for design, dimensions, and [[interchangeable parts|interchangeability]] of transmission chains. For example, the following table shows the principal data of ANSI standard B29.1 (Precision Power Transmission Roller Chains, Attachments, and Sprockets). See the references<ref name="MachinerysHandbook25epp2337-2361">{{Harvnb|Green|1996|pp=2337–2361}}</ref><ref>[http://chain-guide.com/applications/1-1-1-ansi-roller-chains.html]</ref><ref>[http://www.beijingthc.com/transmission_drive_chain/ansi_roller_chains.htm]</ref><ref>[http://www.kana-chain.com/chain/ansi-chain.htm]</ref><ref>{{cite web |title=ANSI G7 Standard Roller Chain - Tsubaki Europe |url=http://tsubaki.eu/chain/ansi-standard-roller-chain/#Single |work=Tsubaki Europe |publisher=Tsubakimoto Europe B.V. |accessdate=2009-06-18}}</ref> for full information.
:NOTE: As of 1 January 2002, ANSI/AMSE B29.1 has been incorporated into ASME B29.100.
{| border="0" cellpadding="6" cellspacing="0"
|- style="background:#232e6d;font-weight:bold; color:white; "
|colspan="8" |ANSI B29.1 roller chain standard sizes
|- style="background:#336ead;font-weight:bold; color:white; "
!Size
!Pitch
!Roller diameter
!Tensile strength
!Working load
|-style="background:#eaeaea;" align=right
!align=center|25
|{{convert|0.250|in|mm|2|abbr=on|lk=on}}
|{{convert|0.130|in|mm|2|abbr=on}}
|{{convert|781|lb|kg||abbr=on|lk=on}}
|{{convert|140|lb|kg||abbr=on}}
|- style="background:#fafafa;" align=right
!align=center|35
|{{convert|0.375|in|mm|2|abbr=on}}
|{{convert|0.200|in|mm|2|abbr=on}}
|{{convert|1758|lb|kg||abbr=on}}
|{{convert|480|lb|kg||abbr=on}}
|-style="background:#eaeaea; " align=right
!align=center|41
|{{convert|0.500|in|mm|2|abbr=on}}
|{{convert|0.306|in|mm|2|abbr=on}}
|{{convert|1500|lb|kg||abbr=on}}
|{{convert|500|lb|kg||abbr=on}}
|- style="background:#fafafa;" align=right
!align=center|40
|{{convert|0.500|in|mm|2|abbr=on}}
|{{convert|0.312|in|mm|2|abbr=on}}
|{{convert|3125|lb|kg||abbr=on}}
|{{convert|810|lb|kg||abbr=on}}
|-style="background:#eaeaea; " align=right
!align=center|50
|{{convert|0.625|in|mm|2|abbr=on}}
|{{convert|0.400|in|mm|2|abbr=on}}
|{{convert|4880|lb|kg||abbr=on}}
|{{convert|1430|lb|kg||abbr=on}}
|- style="background:#fafafa;" align=right
!align=center|60
|{{convert|0.750|in|mm|2|abbr=on}}
|{{convert|0.469|in|mm|2|abbr=on}}
|{{convert|7030|lb|kg||abbr=on}}
|{{convert|1980|lb|kg||abbr=on}}
|-style="background:#eaeaea;" align=right
!align=center|80
|{{convert|1.000|in|mm|2|abbr=on}}
|{{convert|0.625|in|mm|2|abbr=on}}
|{{convert|12500|lb|kg||abbr=on}}
|{{convert|3300|lb|kg||abbr=on}}
|- style="background:#fafafa;" align=right
!align=center|100
|{{convert|1.250|in|mm|2|abbr=on}}
|{{convert|0.750|in|mm|2|abbr=on}}
|{{convert|19531|lb|kg||abbr=on}}
|{{convert|5072|lb|kg||abbr=on}}
|-style="background:#eaeaea;" align=right
!align=center|120
|{{convert|1.500|in|mm|2|abbr=on}}
|{{convert|0.875|in|mm|2|abbr=on}}
|{{convert|28100|lb|kg||abbr=on}}
|{{convert|6800|lb|kg||abbr=on}}
|- style="background:#fafafa;" align=right
!align=center|140
|{{convert|1.750|in|mm|2|abbr=on}}
|{{convert|1.000|in|mm|2|abbr=on}}
|{{convert|38280|lb|kg||abbr=on}}
|{{convert|9040|lb|kg||abbr=on}}
|-style="background:#eaeaea;" align=right
!align=center|160
|{{convert|2.000|in|mm|2|abbr=on}}
|{{convert|1.125|in|mm|2|abbr=on}}
|{{convert|50000|lb|kg||abbr=on}}
|{{convert|11900|lb|kg||abbr=on}}
|- style="background:#fafafa;" align=right
!align=center|180
|{{convert|2.250|in|mm|2|abbr=on}}
|{{convert|1.460|in|mm|2|abbr=on}}
|{{convert|63300|lb|kg||abbr=on}}
|{{convert|13700|lb|kg||abbr=on}}
|-style="background:#eaeaea;" align=right
!align=center|200
|{{convert|2.500|in|mm|2|abbr=on}}
|{{convert|1.562|in|mm|2|abbr=on}}
|{{convert|78000|lb|kg||abbr=on}}
|{{convert|16000|lb|kg||abbr=on}}
|- style="background:#fafafa;" align=right
!align=center|240
|{{convert|3.000|in|mm|2|abbr=on}}
|{{convert|1.875|in|mm|2|abbr=on}}
|{{convert|112500|lb|kg||abbr=on}}
|{{convert|22250|lb|kg||abbr=on}}
|}


For mnemonic purposes, below is another presentation of key dimensions from the same standard, expressed in fractions of an inch (which was part of the thinking behind the choice of [[preferred number]]s in the ANSI standard):


{| class="wikitable" border="1" width="60%"

|- style="background:#eaeaea;" align="center"

! Pitch (inches) !! Pitch expressed <br /> in eighths !! ANSI standard <br /> chain number !! Width (inches)

|- style="background:#fafafa;" align="center"

| {{frac|1|4}} || {{frac|'''2'''|8}} || '''2'''5 || {{frac|1|8}}

|- style="background:#eaeaea;" align="center"

| {{frac|3|8}} || {{frac|'''3'''|8}} || '''3'''5 || {{frac|3|16}}

|- style="background:#fafafa;" align="center"

| {{frac|1|2}} || {{frac|'''4'''|8}} || '''4'''1 || {{frac|1|4}}

|- style="background:#eaeaea;" align="center"

| {{frac|1|2}} || {{frac|'''4'''|8}} || '''4'''0 || {{frac|5|16}}

|- style="background:#fafafa;" align="center"

| {{frac|5|8}} || {{frac|'''5'''|8}} || '''5'''0 || {{frac|3|8}}

|- style="background:#eaeaea;" align="center"

| {{frac|3|4}} || {{frac|'''6'''|8}} || '''6'''0 || {{frac|1|2}}

|- style="background:#fafafa;" align="center"

| 1 || {{frac|'''8'''|8}} || '''8'''0 || {{frac|5|8}}

|-
| colspan="4" | Notes:<br /> 1. The pitch is the distance between roller centers. The width is the distance between the link plates (ie slightly more than the roller width to allow for clearance).<br /> 2. The right-hand digit of the standard denotes 0 = normal chain, 1 = lightweight chain, 5 = rollerless bushing chain. <br /> 3. The left-hand digit denotes the number of eighths of an inch that make up the pitch. <br /> 4. An "H" following the standard number denotes heavyweight chain. A hyphenated number following the standard number denotes double-strand (2), triple-strand (3), and so on. Thus 60H-3 denotes number 60 heavyweight triple-strand chain.

|}

A typical bicycle chain uses 40 series chain with a minimum tensile strength of {{convert|3125|lb|0|lk=on}} and a working load of {{convert|810|lb|0|abbr=on}}. The width of the chain is variable, and does not affect the load capacity.

==References==
{{reflist|2}}

==Bibliography==

* {{MachinerysHandbook25e}}

==External links==
{{Commonscat|Roller chains}}
* [http://chain-guide.com/ The Complete Guide to Chain]
* [http://www.renold.com/Renold/web/site/Support/ChainInformationCentre/Chain_Fundamentals.asp Chain In depth]
* [http://www.scottoiler.com Scottoiler Scotland Ltd.]

[[Category:Chain drives]]
[[Category:Mechanical power transmission]]
[[Category:Mechanical power control]]

[[de:Kette (Technik)]]
[[et:kettülekanne]]
[[es:Cadena de transmisión]]
[[fr:Chaîne (mécanique)]]
[[ja:ローラーチェーン]]
[[nl:Kettingaandrijving]]
[[nn:Kjede]]
[[pl:Łańcuch]]
[[pt:Correia (mecânica)]]
[[it:Catena (meccanica)]]

Revision as of 14:40, 17 March 2011

They roll. Alot.

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