The Complete Guide to Chain

1.1.1 ANSI Roller Chains (RS)

Transmission: General usage

Application Example

Power transmission chains are widely used throughout the world in a variety of applications, including drive, tension, shuttle traction, and transmission reduction operations. Because of this widespread usage, certain international standards are set to ensure that pitch, width, and other key characteristics of chains and sprockets are standardized. In the United States, power transmission chains must meet ANSI B29.1, thus earning the name ANSI chains. In other countries, the chains must meet JIS B1801, ISO 606A, or ISO 1395C.

Construction and Features

  1. ANSI Roller Chains have the same shape and construction as the chain shown in Basics Section 1.1.1. There are 14 sizes of roller chains regulated by ANSI. For easy reference, these are numbered 25, 35, 41, 40, 50, 60, 80, 100, 120, 140, 160, 180, 200, and 240. Some manufacturers include chain numbers 320 and 400 to the list of standardized chains.
  2. Chains with a "5" on the right-hand digit of the chain number are bushing chains. Bushing chains do not have rollers.
  3. Number 41 chain is a narrow variation of number 40.
  4. This chain number indicates the chain pitch. Here's how to decipher the pitch from the chain number. The numbers to the left of the right-hand digit refer to the chain pitch in eighths of an inch. To calculate the pitch, multiply the number by 3.175 mm. For example: 140 = 14 × 3.175 = 44.45 mm pitch, or 14/8 = 1.75 inches.
  5. Each manufacturer adds its own identification stamp prior to the chain number. For Tsubaki, "RS" is the identifier (for example, RS80, RS100). The use of "RS" as an identifier has spread widely; it has become the standard symbol for power transmission roller chains.
  6. There are smaller chains available. Refer to the "Miniature Chain" Section in this book for information on sizes smaller than number 25.


Various sprockets are produced for each size of RS Roller Chain. Sprockets are identified by the type of base material used in manufacture and by the bore. Here are some basic types:

  1. Carbon steel sprockets with plain bores. (Sintered metal or cast iron are sometimes used.)
  2. Carbon steel sprockets with finished bores, keyway, and setscrews.
    TAPER-LOCK® and QD® bores are also available.
  3. 304 stainless steel sprockets with plain bores.
  4. Engineered plastic sprockets with plain bores.
  5. POWER-LOCK® sprockets, which do not require a keyway or setscrew.

Selection and Handling

See Chapters 4 through 7 in the Basics section.