Rudimentary treatise on the construction of cranes and machinery for raising heavy bodies

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J. Weale, 1849 - Cranes, derricks, etc - 112 pages
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Page 76 - To find the deflection of a beam fixed at one end, and loaded at the other : length of beam in inches3 X 32 X weight , tab.
Page 26 - In order to compare these experiments with each other, these results must be reduced to a common standard of comparison, and it is very convenient to express the results of such experiments by the pounds raised one foot high in one minute, this being the method of estimating horses
Page 58 - ... the square of the depth, multiplied by the breadth, and divided by the length between the supports.
Page 100 - ... thirteen equal parts, as shown in Fig. 41, of which the height of the baluster is eight parts, that of the base three parts, and that of the cornice, or rail, two parts. 63. Balustrades intended for actual use in a building — that is, when they are intended to serve the purpose of a hand railing — should not be less than 3 feet nor more than 3 feet 6 inches in height. When used for purely ornamental purposes, however, as in crowning the main cornice of a building, the balustrade should bear...
Page 92 - The rope of the foregoing table " is such as is now generally made by machinery at most of the large rope works, but was formerly known as
Page 26 - ... the working power of men with winches, as applied to cranes. The experiments were undertaken with a view of ascertaining the effect men can produce working at machines or cranes for short periods, as compared with the effect which they produce working continuously. The apparatus, a crane of rough construction in ordinary use, and not prepared in any manner for the experiments, consisted of two wheels, of 92 and 41 cogs, and two pinions, of 11 and 10 cogs ; the diameter of the barrel, measuring...
Page 107 - ... Professor Willis deduces the corollary, that if for a set of wheels of the same pitch a constant describing circle be taken and employed to trace those portions of the teeth which project beyond each pitch line by rolling on the exterior circumference, and those which lie within it by rolling on its interior circumference, then any two wheels of the set will work correctly together. This corollary is new, and constitutes the basis of the system already alluded to. It only remains to settle the...
Page 92 - The old ropemakers, rule was to square the girth of the rope in inches, which, multiplied by four, gave the ultimate or breaking strength of the rope in cwts., and it was a good rule for small cordage, up to 7 inches in circumference. The square of half the circumference was considered to represent the weight of a fathom in pounds." * The old ropemakers, rule for strength is equivalent to 2'51 tons per square inch of section.
Page 74 - ... to the load and to the cube of the length, and inversely as the cube of the depth multiplied by the width, a rule confirmed bj of Professor Barlow.
Page 28 - IV. as giving a near approximation to the maximum power of a man for two minutes and a half ; for in all the succeeding experiments the man was so exhausted as to be unable to let down the weight. The greatest effect produced was that in experiment VI. This, when the friction of the machine is taken into the account, is fully equal to a horse's power, or 33,000 Ibs. raised one foot high in one minute. Thus, it appears, that a very powerful man, exerting himself to the utmost for two minutes, comes...

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