Mechanization

“ The machine, which towers thirty feet into the air and completely dwarfs the attendant, who has it as thoroughly under control as if it were a small file, bites great shining strips forty feet long, maybe, off the surface of the passive metal, and leaves a series of grooves as truly parallel as the art of man can make them. There is no fuss, no sticking, no stop, no noise; the force [71] of electricity or steam, transmitted through wonderfully cut and arranged gear-wheels, is irresistible. ”

“ For example, in a machine-work, the steam-engine, which is the prime mover of the various tools, has a flywheel on the crank-shaft to store and restore the periodical excess of energy arising from the variations in the effort exerted by the connecting-rod upon the crank; and each of the slotting machines, punching machines, riveting machines, and other tools has a flywheel of its own to store and restore energy, so as to enable the very different resistances opposed to those tools at different times to be overcome without too great unsteadiness of motion. ”

“ Energy distributed between two Bodies: Projection and Propulsion.—Hitherto the effort by which a machine is moved has been treated as a force exerted between a movable body and a fixed body, so that the whole energy exerted by it is employed upon the movable body, and none upon the fixed body. This conception is sensibly realized in practice when one of the two bodies between which the effort acts is either so heavy as compared with the other, or has so great a resistance opposed to its motion, that it may, without sensible error, be treated as fixed. ”

“ It constitutes, in my belief, the solution of one of the most difficult mechanical problems, and deserves to be considered as an invention quite apart from any particular means by which it is actuated, whether it is placed upon a self-propelled carriage or a vehicle drawn by any agency, mechanical or otherwise.... The way in which all four wheels are driven simultaneously so as to give the maximum pulling effect by means of elastic connection is in itself sufficient to mark the engine as a most valuable departure from common practice. ”

“ I never imagined that there were so many processes through which all parts of a machine have to be put to perfect them, or that literally thousands of men do some one little thing to every machine turned out. We stood and gazed at men who were polishing the lacquered sides of automobile bodies with their thumbs, dipping them in oil and so rubbing down certain rough places; or at others hovering over automobile motors attached in rows to gasoline tanks and being driven at an enormous rate of speed for days at a time without ever stopping, to test their durability and speed capacity. ”

“ Action and reaction being equal, the power exerted in raising or moving one heavy body must be exerted reversely against the earth, or other fixed body serving as a fulcrum to the lever, or for the attachment of one extremity of a tackle or series of pullies, or for the securing of the capstan spindle. Let the attachments of the machine and its object, however, be both afloat, and then any of the mechanical powers, like that of the wedge, will have an efficiency of double that of its ordinary operation where one part is a fixture. ”

“ And as I am quite mad of this scheme, I beg you will not mention it, or show this paper to Wyat or any body.
"These things are required: 1st, a rotary motion; 2d, easily altering its direction to any other direction; 3d, to be accelerated, retarded, destroyed, revived instantly and easily; 4th, the bulk, the weight, and expense of the machine to be as small as possible in proportion to its use." [10]
He then goes on to throw out various suggestions as to the form and arrangement of the machine, the number of wheels on which it was to run, and the mode of applying the power. ”

“ The prevention of disturbing motions by latent forces is then a principle in the machine. Its application is connected with various objects. When a machine is constructed it is meant to be an arrangement for carrying on some definite mechanical work—it may be the moving of some body, or the alteration of its form, or both together. For such a purpose we require that so soon as motion is caused by any effort in any part of the machine that motion shall be of an absolutely defined nature. ”

“ Had it been otherwise, an animal running on its own wheels would have made its appearance on earth long ago. The shaft of the steam engine could be provided with numerous pulleys, each capable of driving a machine connected with it by a belt. Then arose that marvellous crop of mechanical combinations which brought about the age of mechanism, combinations which, in the last resort, can be reduced to sliding couples and turning couples, and can be catalogued by means of formulæ, like words in a dictionary. ”

“ The lever, the pulley, the wheel and axle, the inclined plane, the wedge and the screw; one or more of which enters into the composition of every machine.
A mechanical power is an instrument by which the effect of a given force is increased, whilst the force remains the same.
In order to understand the power of a machine, there are four things to be considered. 1st. The power that acts: this consists in the effort of men or horses, of weights, springs, steam, &c.
2dly. The resistance which is to be overcome by the power: this is generally a weight to be moved. ”

“ The time during which a machine will continue to perform its work effectually, will depend chiefly upon the perfection with which it was originally constructed upon the care taken to keep it in proper repair, particularly to correct every shake or looseness in the axes—and upon the smallness of the mass and of the velocity of its moving parts. Everything approaching to a blow, all sudden change of direction, is injurious. Engines for producing power, such as windmills, water-mills, and steam-engines, usually last a long time. ”

“ By an appropriate combination of valves and pistons, of wheels and levers, and numerous other contrivances put together in strict conformity with the principles of mechanics, in which the most delicate allowances are made for unavoidable friction, and the attraction of gravitation is either annihilated by counterbalancing weights or turned to account as a source of power, a machine is constructed which strikingly illustrates the importance, not only of the particular character of the different parts of which it is composed, but of the relations of these parts to each other. ”

“ The construction of the machine is such as to modify the natural motion which is impressed upon it, so that it may transmit to the object to be moved that peculiar species of motion which it is required to have. To give a very obvious example, let us suppose that a circular or rotatory motion is required to be produced, and that the only natural source of motion at our command is a perpendicular fall of water: a wheel is provided, placed upon the axle destined to receive the rotatory motion ”

“ With its four-change speed-gear a motor cycle seems better adapted for easy and economical travelling than the human machine. If, however, the human machine has no change of gear, it has one very marvellous mechanism—which we may call a compensatory mechanism, for want of a short, easy name. The more we walk, the more we go hill-climbing, the more powerful do the muscular engines of the heel become. It is quite different with the engine of a motor cycle ”

“ In order to prevent shock when the machine alights, it is necessary to provide something that is strong and, at the same time, yielding, and able to travel through a considerable distance before the machine comes to a state [80] of rest. In the machines which I have seen on the Continent, a very elaborate apparatus is employed, which is not only very heavy, but also offers a considerable resistance to the forward motion of the machine through the air. It consists of many tubes, very long levers and heavy spiral springs, etc. ”

“ In erecting a machine, as in building a house—or, indeed, as in everything that man constructs—the work must be begun at the foundation.
In a machine in which the working parts are carried and contained upon framework, such framework becomes the foundation so far as the erector is concerned.
In a stationary steam engine the cylinder and bed plate form the erector’s foundation while the engine is in the shop, the mason’s foundation being an after consideration.
In a locomotive the boiler is the foundation to which all the other parts are either directly or indirectly affixed. ”

“ The sciences we have been considering under the general name of mechanics, which is derived from a Greek word that means to contrive, invent, construct, have much to do with machinery, with the methods of construction, the propelling forces, and the phenomena produced. There were machinists and some simple machines propelled by human or brute force, by weights and springs, by falling or running water, and air in motion before the laws of motion and forces were understood, or the rude mechanic arts began to assume the character of a science. ”

“ But there are other causes by which the machinery may be deranged; as, although the smaller portions of the machine, if defective, may at any time be taken out and repaired without its being necessary for the machine to stop; yet if the larger wheels are by any chance thrown out of their equilibrium, the machinery may be destroyed just as it would be by a too rapid motion, occasioned by the excess of propelling power. ”

“ All fully developed machinery consists of three essentially different parts, the motor mechanism, the transmitting mechanism, and finally the tool or working machine. The motor mechanism is that which puts the whole in motion. It either generates its own motive power, like the steam engine, the caloric engine, the electro-magnetic machine, &c., or it receives its impulse from some already existing natural force, like the water-wheel from a head of water, the wind-mill from wind, &c. ”

“ An engine which turns a number of machines in a factory should work uniformly. Irregularities of motion may be productive of loss and various inconveniences. An engine would work irregularly either from variation in the production of steam, or from the demands upon the power being lessened or increased. Even if the first of these sources of irregularity could be avoided by care, it is clear that the second could not. Some machines in the mill are occasionally stopped, others occasionally set in motion, and the engine generally tends to go faster the less it has to do. ”

“ So when a man with a system of pulleys raises to the top of a tower a block of granite that four men might lift from the ground he sacrifices in speed what he gains in the new way of applying the force he has for the purpose.
You visit a large manufacturing establishment or the mechanical department of a great national or international industrial exposition and see a whole acre of machinery of all kinds, shafts, wheels, saws, lathes, and spindles in rapid motion, and, astonished at the complications, inquire for the power that carries the whole. ”

“ But the spinning wheel and hand loom could not stand long in the path of power-driven machinery, and now huge, blind machines, with stiff, unbending fingers of metal, comb out the matted masses of raw material, remove the dirt and twigs, straighten out the snarls far quicker and better than could be done by hand, and transform the fibers into beautiful fabrics such as in former days would have been the envy of kings. ”

“ Hence, when a machine was assembled the unyielding metal parts had to be filed and trimmed and hammered to fit them together. If any accident occurred to a machine, the damaged part could not be replaced by another taken from stock. The entire machine had to go back to the shop where an experienced mechanic would make a new part to replace the damaged one. In those days a machine was not manufactured but was built as an individual mechanism, just as a house or a boat is built to-day. ”

“ In the machine-shops systematized by us we have found that there is not one machine in a hundred which is speeded by its makers at anywhere near the correct cutting speed. So that, in order to compete with the science of cutting metals, the machinist, before he could use proper speeds, would first have to put new pulleys on the countershaft of his machine, and also make in most cases changes in the shapes and treatment of his tools, etc. ”

“ The load or resistance to which the machine is applied is not less fluctuating. In mills there are a multiplicity of parts which are severally liable to be occasionally disengaged, and to have their operation suspended. In large factories for spinning, weaving,226 printing, &c. a great number of separate spinning machines, looms, presses, or other engines, are usually worked by one common mover, such as a water-wheel or steam-engine. In these cases the number of machines employed from time to time necessarily varies with the fluctuating demand for the articles produced, and from other causes. ”

“ But another conclusion follows more irresistibly, namely—that the mechanical engineer who devotes his attention to the construction and management of massive machinery, such as pumps, hydraulic and lever presses, looms, and steam-engines, whether locomotive, marine, or other, must, in order to be master of his profession, be thoroughly familiar with every step of their construction; and such familiarity can only be acquired by a course of practical study in the machine-tool shop. ”