Strength of a Chain.

Progress, Volume IV, Issue 5, 1 March 1909, Page 176

Strength of a Chain.

Sometimes one wants to know the strength of a chain when there are no books of reference at hand. Here is an approximately safe method, which is recommended by an expert of some standing : — - Square the number of eighths of an inch in the diameter of the iron of which the links of the chain are made, and strike off the last figure as a decimal, and call the result tons. For example, in a chain with links made of iron lin. in diameter, 8 x 8 = 64, and 6.4 (6t 4 o) tons would be the safe working load. Or, in a chain with links of f iron, 3 + 3 = 9, the safe load would be 9or y 9 o of a ton. These loads are, of course, a very long way from the breaking, or "ultimate" strength of the chains, but it must be remembered that a hoisting chain is subjected to the very worst kind of stresses; for the loads are not only "live" loads, but are generally applied in a series of jerks and sudden stresses. Another important point to remember in using chain gearing is that "the strength

of a chain is the strength of its weakest link." Therefore, all connections must be looked after very carefully. Chain accidents have frequently happened through the breaking or failure of some connecting link, and not of the man chain.