ASME B29.8:2002 pdf download

ASME B29.8:2002 pdf download.LEAF CHAINS, CLEVISES, AND SHEAVES
1 LEAF CHAINS
1.1 Description A leaf chain consists of a series of link plates alternately assembled with pins in such a way that the joint is free to articulate between adjoining pitches. Typical assemblies are depicted in Figs. 1 and 2. 1.2 Numbering and Marking System The chain described in this Standard shall carry the prefix BL. The last two digits of the number following the prefix denote the lacing. The right-hand digit desig- nates the number of link plates in the articulating pitch. The digit to the left of this designates the number of plates in the pin link pitch. The digits to the left of those two digits denote the number of eighths of an inch in the chain pitch. EXAMPLE: BL523 indicates Type BL leaf chain, 5 ⁄ 8 in. pitch with a 2 ? 3 lacing; that is, two plates in the pin link pitch and three plates in the articulating link pitch. Chains shall be marked with the manufacturer’s name or trademark.1.5 Minimum Ultimate Tensile Strength (M.U.T.S.) Minimum Ultimate Tensile Strength (M.U.T.S.), for chain covered by this Standard, is the minimum force at which an unused, undamaged chain could fail when subjected to a single tensile loading test. (a) WARNING: The Minimum Ultimate Tensile Strength is not a “working load.” The M.U.T.S. greatly exceeds the maximum force that may be safely applied to the chain. (b) Test Procedure: A tensile force is slowly applied, in a uniaxial direction, to the ends of the chain sample. (c) The tensile test is a destructive test. Even though the chain may not visibly fail when subjected to the Minimum Ultimate Tensile Strength, it will have been damaged and will be unfit for service. 1.6 Tolerance for Chain Length New chains may have a tolerance of ±0.031 in./ft (2.58 mm/m) when measured under standard measuring load as outlined in para. 1.7. 1.7 Measuring Load This is the load under which a chain is to be measured for length. It is equal to 1% of the minimum ultimate tensile strength. Length measurements are to be taken over a length of at least 12 in. (300 mm). 1.8 Preload All chains shall be preloaded by applying a tensile force equivalent to at least 30% of the Minimum Ultimate Tensile Strength given in Table 2.
2 CLEVISES
This section gives recommended design dimensions of terminal clevises for use with Type B leaf chains. Limiting dimensions herein established are for the purpose of ensuring acceptance of chains built in accor- dance with foregoing standards. 2.1 Design Considerations Care must be exercised in the manufacture and attachment of clevises to ensure equal load distribution across the chain. Failure to do so will seriously reduce the chain load-carrying capacity. It is recommended that the material used for the construction of clevises be through-hardening steel. The clevises and pins used to anchor the chain shall be of adequate strength to withstand at least the breaking load of the chain. 2.2 Clevis Types The clevis may be designed so that the clevis block fits inside the end plates of the chain, or so that the clevis block fits outside the end plates of the chain, as illustrated in Fig. 4.