Whereas superior iron chains
break at a strain at 17 tons per square inch, these weldless steel
chains will stand a strain of 28 to 30 tons, with 20 to 26 per cent.
elongation.
[Illustration: Figures 1. Through 9., 1_a_, 1_b_ and 3_a_
MANUFACTURE OF WELDLESS CHAINS.]
Again, there is greater security in their use from the fact that there
are no welds, and they give warning of the limit of strain to which
they can bear being approached, by elongation, which can be carried to
a considerable extent before the chain breaks. Moreover, over, in
chains made by this process, the links are all exactly alike. Though
the life of a weldless steel chain is said to be twice that of an
ordinary one, the price per length is little more than that of best
iron chains.
They are made in lengths of from 40 to 50 feet, being compressed from
a solid rolled steel bar, the section of which is shaped like a
four-pointed star. In the first place holes are pierced at intervals
down the length of the bar, thus determining the length of the several
links. Then the bar is notched between the holes so as to give the
external form of the links. The next step is "flattening out," which
presses the links into shape on their inner side, but leaves the
openings still closed by a plate of metal.
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