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This equation was solved for each reading of the dynamometer with five pounds pressure on a square inch, and the results tabulated in a convenient form for computing the coefficient of friction from the observed results.

The following table shows the resistance of friction at 100° five hundred revolutions, for various pressures:

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For further detailed results, reference is made to diagram B.

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These results seem to be intimately relevant to the most desirable limit of tension to the spindle band methods of operating cottonspinning machinery. By weighing the band tension in various mills. it was found that the practice of tying bands lacked uniformity. As an example of this variation: in one mill the bands of a single coarse frame are reported to vary from one to sixteen pounds. In another mill, on finer work, a number of spindles had a range of from onehalf to two and a half pounds, and in a third mill the band tension was between the limits of one-fourth to five pounds. The effect of atmospheric changes upon the fiber of textile bands renders it impossible, with the present method of constructing frames, to keep them at a uniform tension, but this variation can be reduced by a little care. Is it not worth while for each spinner to learn the proper band tension required for his special work, and then keep within those limits? The whole power required to run the frame would not vary

in direct proportion to the varying resistance due to the friction of spindles at various pressures; because the resistance of the friction in other parts of the frame connected with the spindles, the actual spinning of cotton fibers, and the alternate contraction and expansion of the bands, are conditions which are more nearly constant and in no case do they vary in proportion with the friction of the spindle; yet the variation is large, as shown by the following experiment made with the frame:

Mr. Geo. Draper, in a communication to the Industrial Record of June 1, 1879, gives the following valuable data on the subject: "A frame of Sawyer spindles was taken, spinning No. 30 yarn, ordinary twist, the front rolls running ninety-five revolutions per minute. The rings, one and five-eighth inch diameter, and the traverse of the yarn on the bobbin, five and a half inches. The dynamometer was applied, and the power required to drive the spindles, with a side pull of the bands, averaging two pounds to a spindle, was ascertained. The bands were then cut off, and a new set put on, with a side pull of three pounds per spindle, and the frame tested again, all things remaining as before. The operation was then repeated at four, five, six, seven, eight and nine pounds side pull per spindle, with the result shown in the following table :

Calling the amount of power required to drive the spinning frame with:

2 pounds tension on the bands....

100

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66

3 4 5 6 7 8 9

117

131

144

159

177

197

considerably more than double.

The results are shown graphically in chart E.

The lubricant used is one of the most important factors in the cost of power. In the present condition of engineering science, it is impossible to state what exact proportion of the power used by a mill is lost in sliding friction, but in a print-cloth mill only about twentyfive per cent. of the power is utilized in the actual processes of carding, spinning, and weaving the fiber, not including the machinery engaged in the operation, leaving seventy-five per cent. of the power as absorbed by the rigidity of belts, the resistance of the air and friction. The coefficient of friction, under the conditions submitted by my oil tester, vary at 100° and five hundred revolutions, from 7.56 per

POWER.

Power required to run a Spinning Frame in full Operation. 200

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cent. in the case of 32° Ex. machinery oil manufactured by the Downer Oil Co., to 24.27 per cent. in the case of neatsfoot oil; and the result of this investigation confirms me in the opinion that the successful operation of a spinning frame is far more closely dependent upon the individual management in respect to the conditions of band tension, lubrication, and temperature of the spinning room, than all other causes combined. Not that some forms of spindle are not superior to others, but that, without wise supervision, the most desirable forms of spindle must fail to show the merits due to the skill of their promoters. It may be stated that, within a close approximation, the lubricating qualities of an oil are inversely proportional to its viscosity; that is, the friction decreases with the cohesion of the globules of the oil, for each other. The endurance of a lubricant is in some degree proportional to its adhesion to the surfaces forming the journal. An ideal lubricant in these respects would be a fluid whose molecules had a minimum cohesion for each other, and a maximum adhesion for metallic surfaces. The viscous oils will also adhere more strongly to metals, and hence, under the conditions of heavy bearings, it is obligatory to use such thick lubricants, knowing that the employment of an oil with great frictional resistance is infinitely preferable to the attempt to use an oil so limpid that it could not be retained between the bearings. With light pressures the more fluid oils are admissible, and in all cases the oils should be as limpid as the circumstances will permit. Oils with great endurance are apt to give great frictional resistance, and in the endeavor to save gallons of oil, many a manager has wasted tons of coal. The true solution of solving the problem of lubricating the machinery of an establishment is to ascertain the consumption of oil, and the expenditure of power, both being measured by the same unit, viz., dollars.

The fluidity of the oils was measured by the following apparatus. A pipette was placed within a glass water-jacket where the temperature was controlled and kept constant by circulation from a reservoir kept at the desired temperature. The capacity of the bulb is twentyeight cubic centimeters and the orifice measures three and a half inches long and .039 of an inch in diameter.

The oil was drawn into the bulb of the pipette, and after the whole was brought to the desired temperature, the time required for its discharge accurately noted by a stop watch.

These observations were made on each of the oils for a series of temperatures varying from 50° to 150° Fah.

If the fluidity of an oil is the measure of its lubricating qualities, these observations would not be identical with the frictional results, because the pressure in this case was that due to a head of about five inches of oil, or about one-sixth of a pound to the square inch and

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