Precision Roller Chain

There was fittle development of roller chain for the first decade or so, but much more development was done in the 1890s. By the early 1900s, roller chains drove the wheels of safety bicycles (Fignre 1-16), as well as automobiles, trucks, and the propellers of the Wright Brothers airplane that flew at Kitty Hawk (Fignre 1-17). 

FIGURE 1-7 An early bucket elevator using cast chain. 

EIGURE 1-10 Cast pintle chain with wear shoes. 

FIGURE 1-11 An M-3 attachment link for a cast pintle chain. 

FIGURE 1-12 Pintle chain with hardened steel bushings. 

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With the increased speed and horsepower capabilities of modem chain drives, the role of lubrication has increased in importance. The precision roller chain is actually a series of connected journal bearings and it is essential that lubrication minimizes the metal-to-metal contact of the pin/bushing joints of the chain. Many factors affect lubrication performance and chain life including heat, improper lubrication, windage, contamination, and oil viscosity. 

The result was that the industry soon became known as the precision roller chain industry. Efforts to standardize, beginning as early as 1913, led to the precision roller chain industry being one of the first in the world to have published standards available to designers and others concerned with roller chains. The basic series of roller chains—precision power transmission roller chains—were the first roller chains to be covered in an American National Standard, ASME B29.1 (then ASA B29a) in 1930. Since then, several varieties of roller chains have been standardized, and they will be covered in subsequent chapters of this book. 

FIGURE 2-10 Standard precision roller chain with bent attachments for conveyor service. 

FIGURE 10-1 Straight attachment plates for precision roller chain. 

Precision roller chains with attachments are often used in conveyors. These chains and standard attachments for them are listed in the ASME B29.1 standard. Some manufacturers oITct precision roller chain with straight-edged link plates for conveyor use. Precision roller chains are usually used where sprocket sizes are limited and where smooth operation is very important. 

Technical data, single-pitch precision roller chains... 

Precision tools are used in the manufacture of roller chains, and a high degree of accuracy is maintained. The chain is made up of links, pins, and bushings, all fabricated from a high grade of steel, with the pins and the bushings ground to ensure accuracy of pitch. 

Roller chains do not require as precise ahgnment as gear or belt drives. 

Silent chain has all of the advantages of roller chain listed above, except for one. Silent chain drives require nearly as precise alignment as gear drives to obtain peak performance and service life. In addition,... 

The sprocket tooth form for engineering steel drive chains is specified in the ASME B29.10 standard. A drawing of the tooth form and the equations for computing the main dimensions are shown in Figure 4-36. It differs from the tooth form for roller chain in that the pitch line clearance and bottom diameter are slightly smaller than the theoretical root diameter. These differences permit the use of a less precisely made tooth form for engineering steel drive chains than the machine-cut tooth form for roller chains. Engineering steel chain drives are often operated in locations where mud, dirt, ore, rock dust, etc. get into the chain. These drives are often exposed to the weather. Pitch line clearance and the undercut bottom diameter both help provide proper chain-sprocket action under such adverse conditions. 

Roller chains can be made to position parts close enough for many automated operations. However, a machine must sometimes put items in a specific place, within extremely close tolerances. In this case it may be better to have the chain position the item close to the desired position and use another means, such as pilot pins, to move the item into the exact position. The machine designer should work closely with an ACA manufacturer to obtain a precise and reliable machine. 

B29.1M-1993 Precision Power Transmission Roller Chains, Attachments and Sprockets Order No. K12793 35.00... 

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