ASME B29.28-2015 pdf download

ASME B29.28-2015 pdf download.High-Strength Chains for Power Transmission and Tension Linkages.
2 HIGH-STRENGTH ROLLER CHAINS
2.1 Nomenclature
high-strength roller chain: roller chain consisting of a series of alternately assembled roller links [see Fig. 1, illustrations (a) and (b)] and pin links [see Fig. 1, illustration (c) and pin link] in which the pins articulate inside the bushings and the rollers are free to turn on the bushings. The pins and bushings are press fit in their respective link plates.
roller link: link consisting of two roller link plates A—A, two bushings B—B, and two rollers C—C.
pin link: link consisting of two pin link plates E—E, and two pins F—F.
NOTES:
(1) Only heavy series high-strength roller chains are covered in this Standard.
(2) Multiple-strand high-strength roller chains are not covered in this Standard.
cotter-type connecting link: link consisting of a pin link plate E, two cross-drilled pins G—G, and a detachable pin link plate D, retained by two cotters H—H. Cotter- type connecting links are used to connect the chain endless on a drive, or to connect the ends of the chain to terminal fittings in a tension linkage [see Fig. 1, illustration (d)]. Some manufacturers may use a retention means other than, but equivalent to, cotters.
NOTE: Offset links for high-strength roller chains are not covered in this Standard.
2.2 General Proportions
The general proportions of high-strength roller chains are the same as for heavy series chains listed in ASME B29.1.
A-5 CENTER DISTANCE
In general, a center distance of 30 chain pitches to 50 chain pitches is most desirable. The distance between the sprocket centers should provide at least a 120-deg chain wrap on the smaller sprocket.
Drives may be installed with either adjustable or fixed center distances. Adjustable centers simplify the control of chain slack.
For drives on fixed centers, an idler or shoe may be used to provide slack adjustment. These devices may also be used to control backlash, or to ensure a 120-deg minimum chain wrap on the smaller sprocket. Idler sprockets should have at least three teeth engaging the chain. There should be at least three free pitches of chain between engagement points on adjacent sprockets.
NOTE: Sufficient housing clearance must always be provided for the slack chain to obtain full chain life.
A-6 ALIGNMENT
Accurate alignment of shafts and sprocket tooth faces provides uniform distribution of the load across the entire chain width and contributes substantially to optimum drive life. Shafting, bearings, and foundations should he suitable to maintain the initial alignment. Periodic maintenance should include an inspection of alignment to ensure optimum chain life.
A-7 GUARDING
Adequate guarding should be provided to contain the chain in the event that a broken chain is thrown off a drive while operating at speed.
If the chain is used in a hoist or other lifting device (not for human passengers), a brake or other restraining device should be provided to stop and hold the load in the event of a broken chain.
A-8 HORSEPOWER RATINGS TABLES
To use the horsepower ratings in Tables A-i through A-9 properly, the following factors must be taken into consideration:
(a) Service Factors. See Table A-10.
(b) Lubrication. The horsepower established from the sprocket and speed combination of the drive under consideration will indicate a method of lubrication. This method or a better one must be used to obtain optimum chain life.
NOTES:
(1) The horsepower ratings permit the use of interference-fit connecting links. Chains using slip-fit connecting links might not meet these ratings.
(2) The horsepower ratings in Tables A-i through A-9 are identical to those for heavy series chains in ASME B29.1. They are reprinted here for convenience.