. The street railway review . lied to motor,746 5°°* : Horse-power supplied to motor at 500 volts,746 500 (2 7^ D R X ) T 2 7^ D R T E Efficiency of motor. ^I 500 X I 746 746 When the motor is started in making a test, water shouldhe poured into the pulley between the flanges of the innercircumference to prevent overheating, also the face of thepulley should be lubricated to insure an even friction, and aconstant pressure on the scale, without which no accuratereading can be taken ; more important is this in regard tothe speed reading. Many experimenters think it advisableto use a separate mea
. The street railway review . lied to motor,746 5°°* : Horse-power supplied to motor at 500 volts,746 500 (2 7^ D R X ) T 2 7^ D R T E Efficiency of motor. ^I 500 X I 746 746 When the motor is started in making a test, water shouldhe poured into the pulley between the flanges of the innercircumference to prevent overheating, also the face of thepulley should be lubricated to insure an even friction, and aconstant pressure on the scale, without which no accuratereading can be taken ; more important is this in regard tothe speed reading. Many experimenters think it advisableto use a separate means of load when taking this reading,and rigidly couple the armature shaft of the motor beingtested to another, which it drives as a dynamo, deliveringcurrent back to the line, and use a variable field shunt as ameans of regulating the load. If this latter method isfollowed in taking speed readings they should be used in con-nection with the scale readings taken when the motor waspassing the same amount of current (amperes).. If the beam be constructed so that the horizontal distancefrom the center of the pulley to the bearing on the scale equalthe radius of a circle 33 ft. in circumference, it will simplifythe calculations considerably, and, besides, a beam of thislength should be of about the right design for an ordinaryplatform scale; the use of a shorter one perhaps causing anoverload when the heavier currents are passing. The scaleshould of course be balanced with the weight of the beam,block, rubbers, etc., when in position, before the motoris started and the test commenced. By placing the pulley and beam first on the armature shaftand obtaining the horse-power exerted for a given amount ofcurrent used, and then changing to the axle and making a testat the same load, the horse-power lost in the friction of thegears and axle bearings can be determined. If the motors are already- under the car, and it is wished tomake a test without removing them, place a screw jack undere
Size: 2531px × 988px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
