ASME International

Leaf Chains, Clevises, and Sheaves
 N B29.8

Annotation

FOREWORD

For many years, roller chain manufacturers have furnished a substantial volume of chains consisting of link plates assembled on pins without the use of bushings and rollers. These chains provide relatively high strength per unit of weight and have found wide usage where sprockets are not required and high-speed power transmission characteristics are not needed.

Previously, variation in link plate thickness, link plate contour, diameter of pins, and the method of lacing limited its interchangeability and restricted its use. For these reasons the Association of Roller and Silent Chain Manufacturers appointed a task subcommittee on September 21, 1951 to develop this Standard.

The scope of the resultant Standard covers the lacing, pin diameter, diameter of link plate holes, link plate contour and thickness, chain widths, and minimum ultimate tensile strengths. The Standard also recommends clevis and sheave design. Supplementary information to guide users in the application of these chains appeared in the 1958 edition and was deleted in 1960.

The 1971 reaffirmation was approved by the American National Standards Institute on September 10, 1971.

Prior to 1975, all B29.8 leaf chain standards included both Type A and Type B leaf chain designs. Type A, the lighter series, was characterized by even or balanced lacing, while Type B, the heavier series, was shown only with uneven or unbalanced lacing of chain links.

During the decade preceding 1975, it became increasingly apparent that the use of Type A leaf chain was declining and that it was being used primarily for replacement. Most new design applications used the heavier Type B design either with the standard uneven lacing or with even lacing, which was shown as standard only for Type A leaf chain. The increased use of Type B chain and the desire to simplify chain standards led the American Chain Association to undertake a revision of B29.8 to: