Elementary lessons with numerical examples in practical mechanics and machine design; with an introduction by John Perry - Softcover

Blaine, Robert Gordon

9781231194706: Elementary lessons with numerical examples in practical mechanics and machine design; with an introduction by John Perry

Softcover

ISBN 10: 1231194707 ISBN 13: 9781231194706

Publisher: RareBooksClub.com, 2012

This specific ISBN edition is currently not available.

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. 1894 Excerpt: ...The resultant stress is 56 tons per square inch. 2. S,Q67S lb. per square inch. 3. 6,428 lb. per square inch LESSON XXIV. OVERHUNG CRANK. CRANK-PINS. LENGTHS OF BEARINGS, ETC. A Very good illustration of combined twisting and bending actions is the case of an overhung crank (Fig. 58). Let P be the total push, or pull, of the connectingrod at right angles to the direction of the crank. Then T = P X A C, and M = P x B C, the resultants of all the forces acting on the journal and crank-pin being assumed to pass through their centres respectively. Then using our rule for combining twisting and bending moments, we have--Te = PxBC + vfP xBC)+(PxA Cp = PBC + V/b C2 + A Ca.-. Te = P (B C + A B). Hence we calculate the twisting moment for an overhung crank as if the crank were of a length equal to the horizontal distance B C, plus the sloping distance A B. Numerical Examples. 1. The greatest pressure of steam in the cylinder of a non-condensing steam-engine, when the connectingrod is at right angles to the crank, is 80 lb. per square inch, the diameter of the piston 12 inches, the length of the crank 12 inches, and the distance from a vertical line through the centre of the crankpin to the centre of the crank-shaft journal 11 inches. Find the diameter of that journal, (a) taking the safe shear stress as 7,800, and (6) as 9,000 lb. per square inch. 2. The crank of a steam-engine is 15 inches long, the horizontal distance from the centre of the crank-pin to the centre of the nearest crank-shaft bearing is 12 inches. If the greatest push or pull of the connecting-rod is 15,000 lb., find the diameter of the crank-shaft, taking the safe shear stress of wrought-iron to be 9,000 lb. per square inch. Crank-pins., / p-j-3. Rule for dimensions of crank-pin: d = '025 The lengt...

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