2-18_R2003_E1972.pdf

,A M E R I C A N N A T I O N A L S T A N D A R D Symbols for Mechanical and Acoustical Elements as Used 0 In Schematic Diagrams ANSI Y32.18-1972 FOR CURRENT COMMITTEE PERSONNEL PLEASE SEE ASME MANUAL AS-I 1 SECRETARIAT INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS PUBLISHED BY T H E A M E R I C A N S.O C I E T Y O F M E C H A N I C A L E N G I N E E R S United Engineering Center 345 East 47th Street New York,N.Y.1001 7 Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.REAFFIRMED 2003FOR CURRENT COMMITTEE PERSONNELPLEASE E-MAIL CSasme.orgNo part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.Copyright 8,1972,by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS Printod in U.S.A.Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.FOREWORD Ever increasing use has been made during recent decades of schematic diagrams in representing mechani-cal and acoustical systems.This development is a natural outgrowth of the same technique as was developed earlier for electric networks.Such diagrams are important because of their usefulness in two connections.First,a mechanical or an acoustical system can be analyzed much more rapidly with a schematic diagram than without.Indeed,systematic methods have been developed in recent years which can generate correct descriptive equations for the system given its schematic diagram and specifications of the properties of each element in the system.Furthermore,the use of such methods tends to minimize blunders in analyses,such as wrong signs for terms,which even the most experienced analyst is apt to make from time to time.Second,as an analyst gains experience with schematic diagrams he develops an insight into the character-istic performance of collections of interconnected elements.Thus he develops an ability to anticipate the performance of a system,at least in a qualitative way,based solely on a study of its schematic diagram.This is an attribute of schematic diagrams that is most useful,as was discovered earlier by electrical and elec-trical and electronics engineers.It is to be noted that each of the foregoing points concerns a determination of the performance of a system;i.e.,an analysis of the system.It is not surprising,therefore,that schematic symbols are constructed primarily to make analyses easier and more straightforward.In recent years,however,there has developed a considerable interest in schematic diagrams in connection with the synthesis problem.From this point of view one starts with a specification of the overall performance desired in a system.If some specifications are then assigned to the schematic diagram,such as the number of juri-ctions and branches in the diagram,it is conceivable that the constitutive equations for the elements can be determined.Although techniques of this sort have not been worked out in detail as yet,they are receiving a lot of attention at the time of this writing and hold great promises for the future.Because this standard concerns a relatively new field,the Writing Group was forced to make some de-cisions.The most important one concerned the question whether it is desirable to try to evolve some stand-ard symbols now rather than to wait a number of yearsin the hope that some fairly uniform practices m.?y evolve.It is recognized that standards are much easier to establish if a unanimity of opinion exists.l 3 e Writing Group believed,however,that a significant contribution could be made to an evolving practice if some sort of a standard practice could be adopted now.No doubt,any user of this standard will find some things that he likes and some that he would like to see changed.Suggestions for improvement based on experience gained in the use of this standard will always be welcome and should be mailed to the Secretary,American National Standards Committee Y32,in care of the ASME.This standard was prepared by a committee working under the auspices of the American National Stand-ards Committee on Acoustics,S1,and the American National Standards Committee on Mechanical Shock and Vibration,S2.It was approved by the above American National Standards Committees and by American National Standards Committee Y32 on Graphic Symbols and Designations on November 23,1971 when it was sent to American National Standard Institute for approval as an American National Standard.The ANSI approval was received on April 20,1972 and it was designated ANSI Y32.18-1972.Ill Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No f