Modern Electric Railway Motors

T. Hanchett George

Description

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. IN presenting this work for public consideration the writer desires to impress upon the reader that it is in tended more particularly for those who have just entered or are about to enter active work in the electric railway field. The object of the book, in short, is to show how electric railway motors are made to-day and why they are made so. The electric railway field is one which is subject to rapid changes of method, and even during the process of preparing this short work for the press, it has been necessary to make substantial changes in text to bring it down to date. Ideas and improvements in electric railway work are occurring almost daily, and what is good practice to-day is history to-morrow, a fact which the reader should bear in mind.

Sujets

• Sciences et techniques
• Electronic engineering

Informations

• Publié par: Forgotten Books
• Date de parution: 27 novembre 2019
• Nombre de lectures: 0
• EAN13: 9780243632176
• Langue: English
• Poids de l'ouvrage: 7 Mo

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presenting this work for public consideration the writer desires to impress upon the reader that it is tended more particularly for those have j ust entered or are about to enter active work in the ele tric railwayfiof the b ok in short is eld The toobj ect show how electric railway motors are made to day and why they are made so The electric railwayfiect toeld is one which is subj rapid changes of method and even during the process o f preparing this short work for the press it has been necessary to make substantial changes in text to bring it down to date Idea and improvements in electric railway work are occurring almost daily and what is good practice to day is history to morrow a fact which the reader should bear in mind The work is largely o f a descriptive character A few general principles are laid down illustrated by present and past practice and comparisons of merits For the benefiare actively employed int of those handling or repairing railway motors a chapter on that subj ect has been added while for those whom the sub interests from the desi ner s standpoint the con cluding ch pter o f the book has been pr pared With the exception of thefinal chapter the book can be easily read and understood by anyone who has had a thorough grounding in Ohm s law For those who wish to acquire general information about electric rail

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wayd that this hop otors it iworkwi ll rov useful In closing the author desires to thankthevariou electrical manufacturing companies which have so gen responded to hi s requests for data without which success could hard l ybe expected for the work In this connection it maybe stated that the table of dimensions and data accompanying this book hasbeen revised and correct dbes of they the engineering for manufacturers whose products are represented and maythere forebe relied upon also dueThank are the publishers have perated with the author in the endeavor to make this work attractive in appear ance and otherwise worthy of the class of readers for whom it is intended

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IRECcurrent railway motors have two principal embers which are essential to their operation namely the armature and thefield ma nets T he rmature may consider as a simple cylinder of iron revolving on its axis of symmetry upon the outer circumference o f which are wires parallel thereto and arrying electric currentAfors the current travels ward andback along the length of the armature it is evident that it must pass in one direction on certain wires and in the reverse on others in fact there are lways two or more zones on every armature carry ing currents in opposite directions T o produce a continuous rotation of the armature we must present to each of these zones a mag etic pole which will repel the wires directly under it and attract those adj acent and the problem o f how these poles are constructed and placed about the armature is the obj ect of discussion in thi s chapter It shoul d notbe dificult to comprehend that theo it maketism iserence how the mag es no di obtained providing it is strong enough to make the armature revolve with su cient power therefore in choosing a orm of ma net for this servce practical

MODERN ELECTR I C RA I LWAYMOTOR

consideration are the onlyterones that hi among these are the following Thefield ma o rnet is the heaviest part o f the and hence to e ect a reduction in the weight motor as a whole careful attention shoul dbe given thand desi n of ae for fieteld mag Thefield excitation must take as little energy as possible theref re a form that has much ma netic le kage or that for other reasons requir excessiv eneryshould be avoided Thefield ma net shouldbe of such form that it canbe easily modeled into an iron clad construction that will protectboth armature andfil froeld coi dust water and m chanical damage It mustbe arranged so that the motor casing canbe easilyopened for inspection and repair Thefield must be b th magnetically and mechan ic lybalanced so as to divide the work evenly between the sections of the armature and avoid sparking and also to distribute the strain equally on the bearings o f the motor The diameter of the motor is usually l imitedby that of the car wheels and under ordinary conditions must necessarily be somewhat less hence i f the motor i s tobthis consideration will playe very powerful a most import nt part in the selection of the form of field m gnet It is now well to discuss the types offiel d magnets that have been used in railway motor desi n and to show in what degree they fulfill the practical require ments j ust recited The reader i s referred to the dia grams Figs to inclusive In these sketches are hown the exciting coils the iron paths provided for the l ines of force that are produced by the coils and lastly the pole pieces that distribute the magnetis

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over the proper zone It too f the armature remembered that these diagrams arebyno n pro p rtional drawingsbut have for their obj ect erely the illustration o f princ iple T ypes o railway motorsf poles are used in A pole that carries a coiliient pole and ones cal led a sal which is formedbythe retuflux of a coi l surround ing a salient pole is called a cons uent po l e A

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chine mayf salient andor hal les all salient have its p h l f consequent Fig shows the common horseshoe type offiel d ma net in which b th poles are salient as this form is never used present practicebecause of its exposed construction the only excuse for giving it a place in this tre tise is that it was thefirst successful form em ployed in a railway motor It used bySpr gue the Thomson H Westinghouse companieouston and in theNo andNrespectivelyo motors Fig shows a form used in experimental motor and to some extent abroad but it has never been adopted to any considerable extent inAmerica