. Electric railways; a treatise on the modern development of electric traction, including practical instruction in the latest approved methods of electric equipment and operation . is kind Uic motorman firstputs the controller on a point that inserts considerable resistancein the circuit. When the motors have slowed down, the electromo-tive force, of course, drops, so that to maintain the same brakingcurrent thcie iinist be a reduction of the amount of resistance, until, G2 ELECTRIC RAILWAYS wlion the car is uliuost at a .standstill, the resistanee is nearly all cutout. It niiijht .seem at fir
. Electric railways; a treatise on the modern development of electric traction, including practical instruction in the latest approved methods of electric equipment and operation . is kind Uic motorman firstputs the controller on a point that inserts considerable resistancein the circuit. When the motors have slowed down, the electromo-tive force, of course, drops, so that to maintain the same brakingcurrent thcie iinist be a reduction of the amount of resistance, until, G2 ELECTRIC RAILWAYS wlion the car is uliuost at a .standstill, the resistanee is nearly all cutout. It niiijht .seem at first that the current would die down heforethe car came to a .stop, but it is found that there is enough inductionin the motor fields to current to flow for a .short time after thecar has stopped. The residual magnetism in the .steel in the fieldsof the motor is sufficient to the motors to begin to generatecurrent when the electric-brake controller is first turned on. The greatest advantage of an cUctric l)rakc using motors asgenerators is in the fact that the braking current instantly falls invalue as .soon as the wheels begin to .slide, and the brake. Kiir. 56. MiiiTUflii Hraljc Slio until the wheels again revolve. In fact, it is almost imj^ the wheels as thev are sometimes skidded bv l)eing l;)cked bvbrake .shoes. This not only prevents flat wheels ])ut insures a (, because when the wheels are locked and .sliding, the brakingor retarding power is only about one-third what it was before thewheels began to .slide. The electric brake requires extra largemotors because of the lieating by the current generatedwhile braking. Westinghouse Electromagnetic Brake. The brake is in ])rinciple similar to the (jencial Ilcclric brakeas far as the use of motors as generators is concerned; but, insteadof the motors l»y means of a magnetic l)rake the car wlucl, a magnetic l)rake .s
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Keywords: ., bookauthoramericanschoolchicago, bookcentury1900, bookdecade1900
