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Description / Abstract:
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:
(a) eliminate Type A leaf chain from the standard;
(b) add even lacing (balanced) to the Type B chain
series;
(c) include a 2½ in. pitch chain to the list of Type B
chain.
These revisions were subsequently included in ANSI B29.8-1977
and approved by the American National Standards Institute on May 4,
1977.
In tabulating dimensional information in this Standard,
customary inch-pound units have been used. Additionally, companion
tabulations have been included that provide metric (S.I.) unit
conversions of these values in accordance with SI-1, ASME
Orientation and Guide for Use of SI (Metric) Units. Certain
formulas and relationships have intentionally been presented only
in customary units to eliminate ambiguity between them and the
tabulated values.
Revisions incorporated in ANSI/ASME B29.8M-1985 provided
additional information on clevises, clevis pins, minimum sheave
size, and lubrication.
Revisions incorporated in ASME B29.8M-1993 included changes in
format, restatement of the definition of Minimum Ultimate Tensile
Strength and, most notably, minor changes in the standard values
for maximum pin diameter and the minimum hole diameter. The
dimensional changes were required to allow a direct, error-free
conversion between conventional units (inches) and metric units
(millimeters).
Revisions incorporated in ASME B29.8-2002 include the
elimination of 8X8 lacing. Tables 1 and 2 were revised to show
minimum width between outside plates (Lm) and
Tables 4 and 5 were revised to show the dimensions for an inside
clevis. An appendix was added containing information on lubrication
and maintenance, connect and disconnect, and general inspection
criteria. Preload and manufacturer's identification marking were
added in compliance with the requirements of ISO 4347.
Revisions incorporated in ASME B29.8-2010 include upside down
rotation of Fig. 1, deletion of the Lm term and
its definition in para. 1.3 and Fig. 3. Also changed is the final
sentence of para. 1.4 concerning manufacturers' responsibility for
ensuring that their chains are properly connected; deletion of
columns headed "Lm" from Tables 1 and 2; and in
Table 1 correcting the Wmax values from the
BL-5xx chains (the prior values were identical to those for BL-4xx
chains). This Standard was approved by the American National
Standards Institute on November 18, 2010.