ASME B29.2M

Description / Abstract: FOREWORD

Preparatory work during the late 1930s and early 1940s by the Silent Chain Division of the Association of Roller and Silent Chain Manufacturers (ARSCM, now the American Chain Association) resulted in agreement on standardization of silent chain primarily on the basis of standardized sprocket tooth design. Since individual chain manufacturers employed various chain joint designs, itwas agreed that standards on chain detail would be limited to ensure interchangeability of chains on sprockets of any number of teeth. At a meeting of representatives of all major American silent chain manufacturers in September 1944, under the auspices of the ARSCM, recommended "Engineering Standards for Industrial Silent Chain and Sprockets" were agreed upon. Formulas for sprocket designwere expanded into tables, whichwere approved and adopted by the ARSCM in April 1945. Supplementary information on sprocket tooth cutters was added, and all of the datawere incorporated in a comprehensive report, Industrial Standards for Industrial Silent Chains, Sprockets, and Cutters. This report, with further refinements by minor revisions in 1949 and 1950, was then submitted to the Sectional Committee for review and approval as an American Standard.

The Sectional Committee accepted the recommendations with some minor revisions in 1950 and referred it to ASME and The Society of Automotive Engineers (SAE) for their approval as sponsors of the Committee, with subsequent transmission to the American Standards Association (ASA) for final acceptance as an American Standard. After approval by ASME and SAE, it was accepted by ASA on November 9, 1950 as American Standard B29.2.

In 1956, the Sectional Committee authorized a revision to the standard to bring it up to date. The revised standard was approved by the American Standards Association on July 11, 1957. This revision was in use for many years and was reaffirmed by ANSI on January 4, 1971. (ASA became ANSI in 1969.)

In 1945, the formulation of a recommended standard for "small pitch" silent chain (pitch sizes less than 3⁄8 in.) and sprocket tooth form became a matter of consideration by ARSCM's Silent Chain Division. As in the case of the larger chain series, the objective was to provide interchangeability of chains on sprockets and the development of recommended practices for power transmission ratings and selection procedure. After a number of years of usage as an ARSCM Industrial Standard, the recommendations became American Standard B29.9 in 1958. Although it was originally anticipated that there might be a need for two or three pitch sizes of the miniature silent chains, only one, the 3⁄16 in. size, has been developed. The information that has heretofore been published as B29.9 was incorporated in the basic Silent Chain Standard, B29.2, as part of the 1982 revision.

In 2006, the B29 Committee undertook a review of the B29.2M Standard and adjusted the contents consistent with developments in industry since the standard had been most recently revised. The list of chain widths was modified to eliminate the ¼in. pitch and some uncommon chain sizes. The illustrations of the side guide silent chain and center guide silent chains were revised; tables of service factors and horsepower rating per inch of chain width were revised, with the 11⁄4 in. pitch deleted in the latter listing; and the errata sheet of the previous revision was corrected in the formula for G (max.).

This Standard was approved by ANSI on February 12, 2007.