. American engineer and railroad journal . roller is used but thechanges of speed are made bywiihdrawing the armature fromthe influences of the field poles,thereby decreasing the field areaand magnetic flux and increas-ing the air gap and resistance,thus increasing the speed. Thechange in speed is not made byjumps, as is the case when acontroller is used, but is grad-ual. The motor runs equallywell in either direction and isreversed in the usual way by re-versing the field current. Themotor is of the four pole shunttype, with the shunt field wind-ings connected in series. Thearmature winding i
. American engineer and railroad journal . roller is used but thechanges of speed are made bywiihdrawing the armature fromthe influences of the field poles,thereby decreasing the field areaand magnetic flux and increas-ing the air gap and resistance,thus increasing the speed. Thechange in speed is not made byjumps, as is the case when acontroller is used, but is grad-ual. The motor runs equallywell in either direction and isreversed in the usual way by re-versing the field current. Themotor is of the four pole shunttype, with the shunt field wind-ings connected in series. Thearmature winding is similar tothat ordinarily used in a shuntmotor. The armature is of a slightlyconical shape, as shown in thedrawing, thus giving a more rapid increase in the air gap and greater increase inspeed for a given lateral adjustment than would bepossible with a cylindrical-shaped armature. As may beseen from the illustration, the commutator end of thearmature is supported by a thrust bearing carry- v\ ji -Sb»——aC; Alt J-^fe 1 X IClfe ^B^^^. APPLICATION OF LINCOLN VARIABLE SPEED MOTOR TO LODCE & SHIPLEY LATHE. ing an annular ball bearing en-closed and protected from dirtto take both the thrust and theradial loads. This thrust bear-ing is actuated by a split leverhaving a central pull on the op-posite sides of the thrust bear-ing, the movement of the leverbeing accomplished by means ofa screw mechanism and handwheel, a spring around the leverconnecting rod being adjusted tobalance the magnetic pull on thearmature. The full range ofspeed may be obtained with afew revolutions of the handwheel. It is claimed that the motormay be overloaded as much as100 per cent, at any speed with-out sparking, and that at lowerspeeds an even greater overloadmay be carried for short peri-ods. It is stated that the effi-ciency at full load of a to 1 motor is from 8G per cent,at 300 to 75 per cent, at1,500 It is also claimedthat the motor speed is not af-fected by varying the loa
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
