. The street railway review . -of a few inches, or about 75° as at C, Iig. >. Bore the beam on each side equidistant from the center ofthe surface of contact with the pulley, and in these holesplace the eye bolts I) with nuts on lop to enable them to betightened at will; have several strands of ^ in. cottonrope spliced into each eye bolt around the inider side of thepulley a-s at li, so that by screwing down the nuts theamount of frictit)n can be regulated and the motor load con-sequently varied. Notch the end of the wooden beam at F,as a bearing for the edge (». Move up an ordinary platfor
. The street railway review . -of a few inches, or about 75° as at C, Iig. >. Bore the beam on each side equidistant from the center ofthe surface of contact with the pulley, and in these holesplace the eye bolts I) with nuts on lop to enable them to betightened at will; have several strands of ^ in. cottonrope spliced into each eye bolt around the inider side of thepulley a-s at li, so that by screwing down the nuts theamount of frictit)n can be regulated and the motor load con-sequently varied. Notch the end of the wooden beam at F,as a bearing for the edge (». Move up an ordinary platformscale, such as is used in the shop for weighing material, andplace upon it four car spring rubbers; on these rubbers rest a block having a triangular section, so as to offer an edge tothe beam, and allow an exact measurement of distancebetween the center of the pulley and this knife edge, tobe made. Place a cut-out, a fuse, a variable resistance andan ammeter in series with the motor with a volt meter inshunt as in Fig. After turning on the current and starting the motor, anydesired load can be obtained by tightening the nuls of theeye bolts, that is, by increasing the friction between beam andpulley. If the horizontal distance from the center of thepulley to the bearing point of the beam on the scale platformwere equal to the radius of the car wheel the poundsindicated upon the scale would be the pull at the periphery ofthe car wheel for the current passing; if this distance wereequal to four times the radius of the car wheel, the scale read-ing should be multiplied by four to obtain the pull at the carwheel. By placing a tachometer against the end of the axle,a speed reading, usually in revolutions per minute, at anyload may also be obtained. To calculate the horse-powerdeveloped by the motor for any given amount of currentpassed, proceed as follows: Multiply the horizontal dis-tance, in feet and decimal parts, from the centre of the i)ulky tothe bearing, on the scale
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
