Spoke (mechanics)

“ Some of these devices are, the wedge, the screw, the pulley and the inclined plane. In some form or other, one or more of these are used in every piece of mechanism in the world.
Because the lever enables the user to raise or move an object hundreds of times heavier than is possible without it, has led thousands of people to misunderstand its meaning, because it has the appearance, to the ignorant, of being able to manufacture power. ”

“ The next class of simple machines, which present themselves to our attention, is that which we have called the cord. If a rope were perfectly flexible, and were capable of being bent over a sharp edge, and of moving upon it without friction, we should be enabled by its means to make a force in any one direction overcome resistance, or communicate motion in any other direction. ”

“ Our rigidity in articulation is the price we have had to pay for easy mastery of a highly necessary symbolism. One cannot be both splendidly free in the random choice of movements and selective with deadly certainty. [11]
There are, then, an indefinitely large number of articulated sounds available for the mechanics of speech; any given language makes use of an explicit, rigidly economical selection of these rich resources; and each of the many possible sounds of speech is conditioned by a number of independent muscular adjustments that work together simultaneously towards its production. ”

“ Another wonder is now promised us—an invention purely mechanical in its nature, by means of which words spoken by the human voice can be, so to speak, stored up and reproduced at will over and over again hundreds, it may be thousands, of times. What will be thought of a piece of mechanism by means of which a message of any length can be spoken on to a plate of metal—that plate sent by post to any part of the world and the message absolutely respoken in the very voice of the sender, purely by mechanical agency? ”

“ As the distances of the power and weight from the fulcrum of a lever may be varied at pleasure, and any assigned proportion given to them, a lever may always be conceived having a power equal to that of any given machine. ”

“ Who can help admiring the exact distribution of the power of resistance at the least possible expenditure of material which is manifested in this wondrous triumph of human genius and skill? The spokes are planted in the solid hub as strongly as the jaw-teeth of a lion in their deep-sunken sockets. Each spoke has its own territory in the circumference, for which it is responsible. According to the load the vehicle is expected to carry, they are few or many, stout or slender, but they share their joint labor with absolute justice,—not one does more, not one does less, than its just proportion. ”

“ Motions Classed.—In problems of mechanism, each solid piece of the machine is supposed to be so stiff and strong as not to undergo any sensible change of figure or dimensions by the forces applied to it—a supposition which is realized in practice if the machine is skilfully designed. ”

“ We see this very clearly in the names of the different parts of machinery, which are taken from the names of similar parts in the human frame. Almost every member of the body is used in mechanical terminology. ”

“ To take our illustration again from mechanics, we may say that if a man is inventing a particular machine,—a sewing machine, a reaper,—nothing is more important than that he should have a precise idea of the operation which his machine is to perform, yet when he is treating the general principles of mechanics he may discuss the lever, or the form of the teeth of wheels which will transmit uniform motion, without inquiring the purpose to which the apparatus is to be applied ”

“ We find that the deepest thoughts can be expressed in the simplest language. "A straight line is the shortest distance between two points" in literature as well as in mechanics. "In simplicity is strength," as Watt said of machinery, and it is true in art as well as in mechanics. ”

“ When the nature and properties of the mechanic powers and other machines have been explained, the force of these observations will be more distinctly perceived. The effects of props and fixed points in sustaining a part of the weight, and sometimes the whole, both of the weight and power, will then be manifest, and every machine will furnish a verification of the remarkable proportion between the velocities of the weight and power, which has enabled us to explain what might otherwise be paradoxical and difficult of comprehension. ”

“ Secondly, The motion and force are transmitted from the prime mover through the train of mechanism to the working piece or pieces, and during that transmission the motion and force are modified in amount and direction, so as to be rendered suitable for the purpose to which they are to be applied. ”

“ The first class includes every machine which is composed of a solid body revolving on a fixed axis, although the name lever has been commonly confined to cases where the machine affects certain particular forms. ”

“ But, on the other hand, the study of Mechanics, in its genuine form, as a branch of education, is fitted to give a most useful and valuable precision of thought on such subjects; and is the more to be recommended, since, in the general habits of most men’s minds, the mechanical conceptions are tainted with far greater obscurity and perplexity than belongs to the conceptions of number, space, and motion. ”

“ A perfectly arranged speaking machine would in fact represent for us that framework of language which consists of mere vowels and consonants, though without most of those expressive adjuncts which go to make up the conversation of speaking men. ”

“ The weights being unequal, we cannot immediately infer anything with reference to the position of the cords, but still we find, as before, that the cords assume a definite position, to which they return when temporarily displaced. ”

“ If the spring or wear of the mechanism were equal for each jaw, the work would be held true, notwithstanding that the jaws be out of line, but such is not found to be the case, and as a result the work cannot be set quite true. ”

“ How to Find Out the Power Developed.—The measure of power produced by an engine, or other source, is so interesting to boys that a sketch is given of a Prony Brake, which is the simplest form of the Dynamometer, as these measuring machines are called. ”

“ A.--The mechanical powers are certain contrivances, such as the wedge, the screw, the inclined plane, and other elementary machines, which convert a small force acting through a great space into a great force acting through a small space. ”

“ But this sign, this instrument is of a wonderful use; words are to the understanding what wheels are to the power of a machine; the power imparts motion, but the machine would not go without wheels. The understanding might have some motion without language, but very slow, very imperfect, very heavy. ”

“ As the mechanical power of the screw depends upon the relative magnitude of the circumference through which the power revolves, and the distance between the threads, it is evident, that, to increase the220 efficacy of the machine, we must either increase the length of the lever by which the power acts, or diminish the magnitude of the thread. ”

“ I have called this system of signs the Mechanical Notation. By its application to geometrical drawing it has given us a new demonstrative science, namely, that of proving that any given machine can or cannot exist; and if it can exist, that it will accomplish its desired object. ”

“ When a cord is used to transmit a force from one direction to another, its stiffness renders some force necessary in bending it over the angle P, which the two directions form; and if the angle be sharp, the exertion of such a force may be attended with the rupture of the cord. ”

“ The shortcomings of human speech are most evident in discussing complicated matters; and for this reason speech is supplemented in the engineering arts by drawings of different kinds. No man ever lived who could describe a complicated machine accurately to a listener, unless that machine differed but little from a machine with which the listener was acquainted. But hand a drawing of even a very complicated machine to a man who knows its language—and the whole nature of the object is laid bare to him ”

“ The cords, which are attached to the cartilages, are to the human speech organs what the two vibrating reeds are to a clarinet or the strings to a violin. They are capable of at least three distinct types of movement, each of which is of the greatest importance for speech. ”

“ So common a machine, it is hardly necessary for us to describe in detail except to mention two steps in the development of the machine, namely the arrangement of the type bars whereby the typewriting is visible to the typist, and secondly the effort to overcome noise by limiting the stroke of the type bar and making it impinge upon the paper with a pressure stroke rather than a hammer blow. ”

“ For from hence are easily deduced the forces of machines, which are compounded of wheels, pullies, levers, cords, and weights, ascending directly or obliquely, and other mechanical powers; as also the force of the tendons to move the bones of animals. ”

“ In any machine, constructed in whatever manner to increase the force which I can exert, it is certain that what I gain in force I must lose in the velocity which I communicate. This is not a contingent truth, borrowed from and limited by observation; for a man of sound mechanical views applies it with like confidence, however novel be the construction of the machine. ”

“ Every instrument, however simple and insignificant, and every machine, however large or complicated, is an example of some one of the six Mechanical Powers, or of a combination of them. I will proceed to consider each of these separately. ”

“ It is often necessary that the rod to which reciprocating motion is communicated shall be urged by the same force in both directions. A wheel partially furnished with teeth, acting on two racks placed on different sides of it, and both connected with the bar or rod to which the reciprocating motion is to be communicated, will accomplish this. Such an apparatus is represented in fig. ”

“ The teeth of wheels of any figure, as well as of circular wheels, may be traced by rolling curves on their pitch-surfaces; and all teeth of the same pitch, traced by the same rolling curve with the same tracing-point, will work together correctly if their pitch-surfaces are in rolling contact. ”

“ Reuleaux's title I have therefore been compelled to change the first part to Kinematics of Machinery. It is very unfortunate that we have as yet no word for the study of motion as change of position merely. ”

“ The nature of our present invention consists principally in our providing, instead of that a motive-power wheel having its axis upon fixed bearings in an eccentric position and turning in an oscillating cylinder. ”

“ For the analysis of mechanical phenomena, a metrical notion, derived from experience, and bearing the designation work, has proved itself useful. A machine can be set in motion only when the forces acting on it can perform work. ”

“ The dynamic apparatus is composed of the head, the torso and the limbs. As in the vocal apparatus, we have the lever, the impelling force, and the fulcrum.
The dynamic apparatus produces gesture, which renders the moral or normal state; as the voice expresses inflection and reveals the sensitive state.
The head must be studied under two relations: as the agent of expression through its movements, and as the centre of attraction ”

“ The organ of speech is perhaps the most delicate and perfect motor apparatus in the whole body. It has been calculated that upwards of 900 movements per minute can be made by the movable organs of speech during reading, speaking, and singing. It is said that no less than a hundred different muscles are called into action in talking. Each part of this delicate apparatus is so admirably adjusted to every other that all parts of this most complex machinery act in perfect harmony. ”

“ The higher hand may, if out of alignment, pass the figure when the lower hand approaches the ninth point in its dial, this causing the person to read the figures one, ten, hundred or thousand units too much. ”

“ What would there be strange in the mechanician, after constructing the most beautiful and ingenious piece of mechanism it is possible to conceive of, speaking to it and admiring the beauty, regularity and order of its motions? ”

“ This rule is true for all kinds of levers, blocks and tackles or pulley systems, automobile and bicycle gears, belt systems, cog systems, derricks, crowbars, and every kind of machine. In most machines you either put in more force than you get out and gain motion, or you put in more motion than you get out and gain force. ”

“ The permanent impressions of the vibrations of the voice are now made. It remains to obtain from these impressions the aerial vibrations which made them. Nothing is simpler. The plate A, with its point, P, is moved away from the cylinder by pulling toward you the lever H G. Then the motion of the cylinder is reversed till you have brought opposite to the point P the beginning of the series of impressions which it has made on the foil. Now bring the point up ”

“ Cut the spokes all the same length, not straight across but slanting, so as to make a point that can easily be pushed down between the weaving. Then hold them in water for a few minutes. When they are quite [42] pliable the first spoke (any one you choose to begin with) is pushed down between the rows of weaving beside the one to the left of it or spoke No. 2. No. 2 is pushed down beside the next one to the left, No. 3, and so on all the way around the mat. Take care that at least an inch of each spoke is pressed below the edge of the mat. ”

“ The study of kinematics has been considered for nearly 80 years as a necessary part of the mechanical engineer's training, as the dozens of textbooks that have been published over the years make amply clear. ”