. Electric railways; a treatise on the modern development of electric traction, including practical instruction in the latest approved methods of electric equipment and operation . )osition selectedfor its toughness and wearing ((ualities. Trolley Harp. The trolley harp, which is placed on the end. Fig. -10. Trolley Harp. of the trolley pole and in which the trolley wheel icvolvcs, usuallyhas some means for making electrical contact with the wheel inaddition to the journal bearing. In the harp illustrated in , which is a typical form, this additional contact is secured by aspring bearing
. Electric railways; a treatise on the modern development of electric traction, including practical instruction in the latest approved methods of electric equipment and operation . )osition selectedfor its toughness and wearing ((ualities. Trolley Harp. The trolley harp, which is placed on the end. Fig. -10. Trolley Harp. of the trolley pole and in which the trolley wheel icvolvcs, usuallyhas some means for making electrical contact with the wheel inaddition to the journal bearing. In the harp illustrated in , which is a typical form, this additional contact is secured by aspring bearing against the side of the hub of the wheel. Since trolley wheels re-volve at a very high speed, someunusual means of lubricationmust be provided, since thereis no opportunity for ordinaryoil or grease , in the shape of what,is called a graphite bushing,is most commonly used. Thisis a brass bushing, w^hich ispressed into the hub of thetrolley wheel. In this is a spiral groove filled with graphite which is supposed to furnishsufficient lubrication as the wears. Roller-bearing trolleywheels have been used to a limited extent, with considerable successin .some cases. Some companies have done away with the graphitebushing, and have provided a very long journa
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Keywords: ., bookauthoramericanschoolchicago, bookcentury1900, bookdecade1900
