Editing Roller chain (section)

==Variants==
[[File:Roller Chain Render (with numbers).png|thumb|right|Layout of a roller chain: 1. Outer plate, 2. Inner plate, 3. Pin, 4. Bushing, 5. Roller]]
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 digits 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 chain with half-inch pitch is a No. 40 while a No. 160 sprocket has teeth spaced 2&nbsp;inches apart, etc. Metric pitches are expressed in sixteenths of an inch; thus a metric No. 8 chain (08B-1) is equivalent to an ANSI No. 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. Chain with a removable link or pin is also known as "cottered chain", which allows the length of the chain to be adjusted. Half links (also known as "offsets") are available and are used to increase the length of the chain by a single roller. Riveted roller chain has the master link (also known as a "connecting link") "riveted" or mashed on the ends. These pins are made to be durable and are not removable.<ref>{{cite web|url=http://panzit.com/library/chain/riveted-vs-cottered-chain/|title=Riveted vs Cottered Chain - Panzit Library|work=panzit.com|access-date=17 January 2015|archive-url=https://web.archive.org/web/20120426080753/http://panzit.com/library/chain/riveted-vs-cottered-chain/|archive-date=26 April 2012}}</ref>

===Horseshoe clip===
A ''horseshoe clip'' is the U-shaped spring steel fitting that holds the side-plate of the joining (or "master") link formerly essential to complete the loop of a roller chain. The clip method is losing popularity as more and more chains are manufactured as endless loops not intended for maintenance. Modern motorcycles are often fitted with an endless chain but in the increasingly rare circumstances of the chain wearing out and needing to be replaced, a length of chain and a joining link (with horseshoe clip) will be provided as a spare. Changes in motorcycle suspension are tending to make this use less prevalent.

Common on older [[motorcycle]]s and older [[bicycles]] (e.g. those with [[hub gears]]) this clip method cannot be used on bicycles fitted with derailleur gears, as the clip will tend to catch on the gear-changers. 

In many cases, an endless chain cannot be replaced easily since it is linked into the frame of the machine (this is the case on the traditional bicycle, amongst other places). However, in some cases, a joining link with horseshoe clip cannot be used or is not preferred in the application either. In this case, a "soft link" is used, placed with a chain riveter and relying solely on friction. With modern materials and tools and skilled application this is a permanent repair having almost the same strength and life of the unbroken chain.