POWER, Utilization of. The economical production of manufactures and the convenient, adaptations of time- and labor-saving devices in all the various lines of constructional work have exerted a wonderful influence in the upbuildtng of American industries. Among other signifi cant features the present tendency is marked by the adaptation of compressed air and the ap plication of electric power to machine driving.
In the use of compressed air, the facility of adaptation to various requirements which are in many cases additional to the supply of motive power, is a valuable feature peculiar to this system and one which is susceptible of exten sion along many lines. The labor cost in most machine shops and other works is so much greater than the cost of power that any expedi ent by which the labor cost may be appreciably reduced is justified, even though the efficiency of the agent itself be low. Whenever new methods or agencies cause an increased produc tion with a given outlay for labor, these methods will supersede the old, even though the cost of the power required be greater than be fore. The saving of power is a consideration secondary to the advantages and economical output obtained by its use. While economy in the use of power should therefore be secondary ii to increased output, yet careful attention to de tails will often greatly reduce the useless waste of power. Engineers have recognized that there is a very great percentao'e of loss due to shaft friction, which, in railroad and other shops where the buildings are more or less scattered may be as great as 75 or even 80 per cent of the total power used. In the ordinary machine shop this loss will probably average from 30 to 50 per cent. No matter how well a long line of shafting may have been erected, it soon loses its alignment and the power necessary to rotate it is increased.
Manufacturers are realizing the loss of power which ensues from the oresent system of mechanical transmission, and there is an in creasing tendency to introduce different methods by which a part of this loss will be obviated. Among these are the adoption of hollow and lighter shafting, higher speeds and lighter pul leys, roller and ball bearings in shaft hangers, and the total or partial elimination of the shafting.
Subdivided Power.— Independent motors are often employed to drive sections of shaft ing and isolated machines, and among these are . found steam and gas-engines, electric motors, compressed air and hydraulic motors, although the latter have not been used for this purpose to any appreciable extent. In the choice of motors, until quite recently the steam engine has generally been used, especially where the units are relatively large, but the advantages possessed by electric driving has caused the electric motor to displace the steam engine in many cases. An interesting example of this is noted in the Franklin Sugar Refining Com pany of Philadelphia, in which there were formerly some 90 Westinghouse engines about the works, many of them being of 75 and 100 horse power each; others of 5 and 10 horse power only. At the present time these have all been replaced with electric motors. A similar subdivided-power plant involving nearly 50 steam engines was erected some years ago at the Donnell Print Works of the United States Finishing Company at Pawtucket, R I. More recently many of the steam engines have been replaced by electric motors, but there are still 27 engines in use in this plant. It was not so many years ago that several large and eco nomical Corliss engines were replaced at the Baldwin Locomotive Works by a greater num ber of small, simple-expansion engines, which actually required about 15 per cent more steam per horse-power hour than the Corliss engines. This loss, however, was only apparent, for by increasing the number of units and locating them at convenient centres of distribution much of the shafting and belting could be dispensed with and an actual saving of power was ob tained. Later, the simple engines were re placed by a number of compounds, some 18 be ing in service and these showed a saving of 36 per cent over that obtained by the use of the Simple engines. Subsequently, however, the electric motor (q.v.) has superseded the steam engine for this work, as its economy and con venience over the latter are now thoroughly recognized.