Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1884 edition. Excerpt: ...on the other hand, when a chain is so well made that all its links are of uniform strength, or nearly so, the endurance is much greater, and it will go on for an indefinite period without breaking. At the same time, a change for the worse overtakes all chains in course of time, that is, if they are in constant use; and, in consequence, it is a rule in the War Department, that all chains of cranes or slings are to be drawn through the fire, and thereby annealed, periodically, which has the effect of restoring the quality, by putting the material of the links into a condition of equilibrium. By this course, their life is protracted indefinitely. After the chains are annealed, they are then subjected to a proof strain, which is the half of the ultimate strength, and double the usual working load, according to size, which is as under: --Chains are of two sorts: first, the open link chain, which is commonly used for cranes and like purposes; and second, the stayed link chain, which is used for cables and some other purposes. It is to be noted that, whatever the explanation may be, the stayed link, when made of the same iron as the open link, is stronger than the other, nearly in the proportion of 9 to 6. To take, for example, an inch chain, that is to say, a chain made with iron one inch in diameter, the ultimate strength of the open link is about 24 tons, while that of the stayed link may reach 30 tons. The office of the stay is to prevent the collapse of the link, and thereby to intercept the shearing action due to the wedge action of the one link within the other. The great practical objection to the stayed link chain is its weight, and its extreme roughness in working over pulleys. A good approximate rule, for mentally estimating the..
