Cyclopedia of Mechanical Engineering Volume 7; A General Reference Work on Machine Shop Practice, Tool Making, Forging, Pattern Making, Foundry, Work, Metallurgy, Steam Boilers and Engines, Gas Producers, Gas Engines, Automobiles, Elevators, Refrigeratio (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 Excerpt: ...by constantly noting the "mechanics" of the simple structures which he sees in his daily routine of work. Aside from machinery, in which the "mechanics" is often obscure, the world is full of simple examples of natural strength and symmetry, explainable by application of the principles of pure "mechanics." Posts and pillars are largest at their bases; overhanging brackets or arms are spread out at the fastening to the wall; heavy swinging gates are counter-balanced by a ponderous weight; the old-fashioned well sweep carries its tray of stones at the end, adjusting the balance to a nicety; these are examples of things depending for their form and operation upon the principles of "mechanics." The building of them involved "constructive mechanics," and yet their constructor perhaps never heard of the science, using merely his natural sense of mechanical fitness Such simple reasoning is, however, Constructive Mechanics. Forces, Moments, and Beams. Machines are nothing but a collection of (l) parts taking direct stress, or (2) parts acting as loaded beams. Forces acting without leverage produce direct stress on the sustaining part. Forces acting with leverage produce a moment; the sustaining member is a beam, and the stress therein depends on the theory of beams, as explained in "Mechanics." An example of the first is the load on a rope, the force acting without leverage, and the rope therefore having a direct stress put upon it. An example of the second is a push of the hand on the crank of a grindstone. A moment is produced about the hub of the crank; the arm of the crank is a beam, and the stress at any point of it may be found by the method of theory of beams. Tension, Compression, and Torsion. The ...