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Mechanisms in Modern Engineering Design
Mechanisms in Modern Engineering Design
A Handbook for Engineers, Designers, and Inventors
Ivan I. Artobolevsky
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One of the problems facing the modern theory of mechanisms is the study and systematization of the huge inheritance accumulated in mechanical engineering practice and consisting of numerous mechanisms applied in various machines, instruments and devices.
An analysis of this data and its classification into the various kinds of mechanisms have shown that their systematization should be broken down into two stages. The first is the compilation of collections of mechanisms employed in all branches of the engineering industries. The next stage consists of collections compiled for different branches, such as mechanisms for precision instruments, mechanisms of machine tools, mechanisms of aircraft engines.
The need of such systematically compiled data is evidently very great because information on the various kinds of mechanisms that have been devised is scattered, for the most part, among diverse reference sources: textbooks, monographs, journals, patent applications, etc. This data is difficult to use because some of the editions may be more or less unique, and because the data does not, as a rule, contain the necessary descriptions, classification and system that would enable a mechanism to be quickly selected for some definite purpose specified by a designer.
It is of equal importance, in the author's opinion, to meet the needs of inventors. A vast number of inventions are being made in the USSR and abroad, and their quantity is increasing year by r year. Inventors require convenient handbooks where they can readily find elementary schemes of mechanisms' that can accomplish the forms of motion needed for the designs* they propose.
To meet this demand, in 1947-52 the author compiled a four volume work called Mechanisms which was published (in Russian) by the USSR Academy of Sciences. This work contains drawings and descriptions of 4000 mechanisms and includes those made up of hydraulic, pneumatic and electrical devices, as well as purely mechanical systems. This four- volume work has long been out of print and, judging from letters received by the author from a great many engineers, designers, technicians and inventors, a new edition is more than timely. To meet this demand the author has prepared the present completely revised and considerably supplemented edition. This work is to comprise five volumes. The first two volumes contain drawings and descriptions of lever mechanisms, i.e. mechanisms based on kinematic chains made up of lower pairs. The third volume is devoted to gear mechanisms. The fourth volume contains cam, friction and flexible-link mechanisms. The final volume is to deal with hydraulic, pneumatic and electrical mechanisms.
The present work, Lever Mechanisms , in two volumes, deals with mechanisms having lower pairs and contains drawings and descriptions of 2288 mechanisms. The author has mainly selected general-purpose mechanisms that find application in many branches of industry. Certain special- purpose mechanisms employed mainly in single branches of industry have also been included. The reason is that they may prove of interest to other branches of industry. These mechanisms have been assigned a separate subgroup: mechanisms of functional devices.
In this work the author has taken into consideration all the suggestions and remarks made by the readers of the earlier edition. One such suggestion concerns the addition of sub- groups dealing with kinematic pairs and movable joints. Any mechanism comprises kinematic chains consisting of these elements. Consequently, it is of prime importance for designers to correctly establish the structure of the mechanism they are dealing with and to select the necessary combination of kinematic pairs. The kinematic pairs and movable joints are illustrated by drawings which provide a more pictorial representation than the conventional symbols used for kinematic diagrams. This should facilitate the designing process. Descriptions of mechanisms of especially complicated structure have been expanded in comparison to the earlier edition. This was done by the well-founded request of certain readers who found difficulty in understanding some structures of mechanisms that were too briefly dealt with previously. Wherever necessary the author has supplemented the description with analytical relationships of the parameters of the mechanisms, as well as with their kinematic characteristics: displacements, velocities, paths, etc.
In working on the present edition the author gave much attention to the problems of systematizing and classifying the mechanisms. The structures of the mechanisms were carefully checked. All errors found in the reference material from quite essential ones, have been corrected. In all doubtful cases, investigations were conducted on the parameters of the mechanisms with the atm of checking their properties against those claimed by the sources from which they were taken (this refers, in the main, to guiding mechanisms, dwell mechanisms, etc,).
The author's aim was to produce a handbook for engineers and technicians of all ranks, as well as inventors, and not only for experts in the field of mechanisms theory. Hence, he has conscientiously avoided special terminology and notation intelligible only lo experts in this line. The author has tried to use the simplest possible drawings furnished with the simplest possible descriptions that should be understandable even to persons without any special engineering training.
In collecting the mechanisms the author used extensive references, some in Russian and some in other languages. These references are not listed here since they would require too much space and could render no essential service to the reader unless supplemented by a great many additional references and notes. As concerns the overwhelming majority of the mechanisms given here, it is extremely difficult to establish priority with respect to whom they were first pro- posed and/or described by. Exceptions have been made only for mechanisms whose designers are generally known. In these cases, the designer's or inventor's name has been given to the mechanism.
As far as practicable, the author tried to keep the drawing of each mechanism the same as is given in the source where it was found, changes being made only whenever necessary to clear up the structure and kinematics. This means that many drawings from the older reference sources may lack some details and components that would certainly be found in up-to-date designs, but which were not in use at the time when the given mechanism was proposed (shapes of pistons and cylinders, shape of cross-head castings, etc.).
Table 1. Classification of Mechanisms Based on Structural Features 17
Table 2. Classification of Mechanisms Based on Functional Features 32
SECTION ONE. ELEMENTS OF MECHANISMS 43
1. Kinematics Pairs (I through 54) 45
2. Movable Joints (55 through 119) 72
SECTION TWO. SIMPLE LEVER MECHANISMS Ill
1. Lever Mechanisms (120 through 162) 113
2. Gripping, Clamping and Expanding Mechanisms (163 through 245) 139
3. Balance Mechanisms (246 through 251) 189
4. Brake Mechanisms (252 through 257) 192
5. Stop, Detent and Locking Mechanisms (258 through 334) 195
6. Switching, Engaging and Disengaging Mechanisms (335 through 361) 233
7. Indexing Mechanisms (362 through 405) 250
8. Sorting and Feeding Mechanisms (406 through 429) . . . 276
9. Governor Mechanisms (430 through 440) 292
10. Clutch and Coupling Mechanisms (441 through 459) . . . 298
11. Mechanisms of Measuring and Testing Devices (460 through 478) 309
12. Hammer, Press and Die Mechanisms (479 through 483) 321
13. Key Mechanisms (484 through 487) 324
14. Mechanisms of Materials Handling Equipment (488 through 492) 327
15. Safety Mechanisms (493 and 494) 330
16. Link-Length Adjustment Mechanisms (495 through 502) 332
17. Mechanisms for Mathematical Operations (503 through 506) 336
18. Contacting Lever Mechanisms (507 through 523) 339
19. Mechanisms of Other Functional Devices (524 through 538) 349
SECTION THREE. LINKWORK 359
1. General-Purpose Four-Link Mechanisms (539 through 581) 361
2. General-Purpose Five-Link Mechanisms (582 through 589) 387
3. General-Purpose Six-Link Mechanisms (590 through 608) 391
4. General-Purpose Multiple-Link Mechanisms (609 through 622) 403
5. Parallel-Crank Mechanisms (623 through 640) 415
6. Crossed-Crank Mechanisms (641, 642 and 643) 427
7. Guiding Mechanisms and Inversors (644 through 740) 429
8. Mechanisms for Mathematical Operations (741 through 745) 499
9. Dwell Mechanisms (746 through 762) 503
10. Mechanisms for Generating Curves (763 through 771) 518
11. Operating Claw Mechanisms of Motion Picture Cameras (772 through 780) 526
12. Balance Mechanisms (781 through 795) 531
13. Clutch and Coupling Mechanisms (796 through 801) .... 540
14. Sorting and Feeding Mechanisms (802 through 808) . . . 543
15. Safety Mechanisms (809 , 810 and 811) 550
16. Governor Mechanisms (812 through 815) 552
17 . Mechanisms of Measuring and Testing Devices (816 through 824) 555
18. Indexing Mechanisms (825) 562
19. Mechanisms of Materials Handling Equipment (826 through 830) 563
20. Pantograph Mechanisms (831 through 857) 567
21. Brake Mechanisms (858 through 876) 589
22. Hammer, Press and Die Mechanisms (877 and 878) . . . 600
23. Mechanisms of Other Functional Devices (879 through 912) 601