Roller chain is a steel linked chain that utilizes roller bushings at each connecting link. The bushings aid the chain in riding smoothly around a sprocket and give the chain long life as well as strength. Roller chain is commonly found on bicycles and farming machinery and is also a primary component in automobile transmissions and transfer cases. Some high-performance types of roller chain use small rubber O-rings at each end of the bushings to aid in the retention of oil, which helps keep the chain in peak condition.
There are many types of roller chain, each intended for a specific purpose. In the U.S., roller chain is sized by the American National Standards Institute or ANSI with the most common sizes being 40, 50 and 60. The size of the chain is reflective of the pitch of the chain in eighths of an inch (0.3175 centimeters), this is denoted by the first digit, and the final digit noting the strength of the chain. While 0 represents standard chain and 1 represents lightweight chain, 5 is used to show bushed chain with no rollers. This means that a standard bicycle chain with a half-inch (1.27 centimeters) pitch would be a size 40 chain.
The typical roller chain is comprised of links that are fused together by pins. The pins are driven through the ends of each link and held in place by friction. Each chain is connected at the ends to form a complete circle or chain loop by a master link. The master link is a link of chain that uses a clip to hold the sides in place rather than being a friction fit. Roller chain can be shortened by removing links with a chain breaking tool and lengthened by adding whole or a half links.
Lubrication and proper tension is critical to assure long life for any roller chain. A chain should never be run tight. There should always be a slight amount of slack in a properly adjusted chain. The school of thought is approximately 2 percent to 4 percent of the distance between the centers of the sprockets. Clean, light-weight oil should be used to keep the chain properly lubricated.
The various uses for roller chain include not only bicycles, but conveyors, automobile timing chains and chain saws. By attaching tiny cutting teeth to a chain, a chain saw is able to cut its way through a tree in a rapid manner. In another application, small lengths of chain are attached to a handle, allowing plumbers to grip and twist pipe sections.