Page:The Kinematics of Machinery.djvu/600

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�KINEMATICS OF MACHINERY.

�(5.) By making^ the length 3'4 less instead of greater than 4'5 we obtain in the chain a motion differing very greatly from any occurring in either of the former cases. Fig 438 shows this arrangement. While in Figs. 436 and 437 the whole motion of b relatively to a was equal to twice the distance 4'5, that is twice the length e, it is now equal to twice the distance 4' 3. I have formerly suggested this mechanism as a leading train for punching, riveting or stamping-machines, and given it the name of toothed- eccentric* (cf. also p. 300).

����Fro. 439.

�FIG. 440.

�FIG. 441.

�(6.) Leaving still the links a and b infinite, hut giving to 1/5 some finite value, we obtain a chain represented in a general form in Fig 439. If we here make 3'4 <^e, we have the chain represented in Fig. 440, which I formerly called the general case of the toothed-eccentric. Placing this chain on a we obtain a mechanism which may serve to give to a link (b) reciprocations of varying stroke. We obtain an interesting case if we make the toothed- wheels equal and the lengths 1*5 and 3 - 4 also equal, and at the same time place the latter symmetrically to a, as in Fig. 441. I have

mechanisimis. " In this article I examined the whole series of these mechanisms. I had not then recognised their connection, above explained, with the planet-wheel trains. R.
 * See Civil Ingeniemr, 1858, p. 4 ; " Das Zahnexzentrik, ein neuer Bewegungs-

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