Sprockets and Chains

General Chain Overview – Roller Transmission and Engineered Steel Chains

Due to the diverse ranges of chains now available, this article will look at chains which are fabricated from steel, have link plates, bushes and pins and are assembled with an interference fit complete with pin ends that are spun or riveted. This type of chain includes standard roller transmission chains and engineered steel or conveyor chains. Examples of chains that are not covered include cast link, silent running, leaf chain and those that are molded from plastic such as integral slat chains/flat top chains.

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Standard Roller Chain Numbering System


British Standard Chain Numbering

BS chains are measured in 16ths of an inch.  For chains 06B and larger, the pitch can be found from dividing the chain number by 16 i.e.

06B Chain Pitch (mm) = 06/16 × 25.4 = 9.525mm

A hyphenated number after the initial chain number indicates the number of chain strands. For example, 24B-1 is a single strand, 24B-2 is two strands and 24B-3 is three strands.


ANSI Chain Numbering

ANSI chains are measured in 8ths of an inch, but the right-hand digit of the chain code also designates if the chain is standard (0), lightweight (1) or rollerless (5).

For example, a 41 chain would be a lightweight chain with a 4/8” pitch while 100 chain would be standard, having a pitch of 10/8”.

‘H’ after the chain number designates the chain as ‘Heavy’, adding an extra 1/32” to the thickness of the standard link plate. For example, a 100H chain would have a 4.8mm thick link plate instead of the standard 4mm thick plate.

A hyphenated number after the initial chain number indicates the number of chain strands. For example, 100-1 is a single strand, 100-2 is two strands, 100-3 is three strands and 100H-2 is heavy duty 100 series chain with 2 strands.


ANSI Roller Chain Proportions

ANSI roller chains have major dimensions that are roughly proportional to the chain pitch. These proportions were obtained through research and experimentation and are used for chains that conform to ASME B29.1;

Roller width ≈ 5/8 of the pitch.
Chain (roller) width ≈ 5/8 of the pitch.
Pin diameter ≈ 5/16 of the pitch.
Link plate thickness ≈ 1/8 of the pitch.
Maximum roller link plate height ≈ 0.95 × pitch.
Maximum pin link plate height ≈ 0.82 × pitch.