Page:The Kinematics of Machinery.djvu/216

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�KINEMATICS OF MACHINERY.

�Fig. 155, our mechanism becomes really a closed chain.* To this I shall have to return again, looking at the question from another point of view.

If the two longer links I and d are to be paired instead of the shorter ones, we have only to notice that it is the vertices F and G,

��FIG. 154.

and E and ff } which touch each other in the change-positions. By placing in these points again a pin and corresponding gab, Fig. 156, we have again a pairing which effectually closes the chain. We have here then two solutions of the problem before us. If it were wished it would be possible to close the chain at one dead point by one method, at the other by another.

The following is another interesting example of the pair-closure of a chain having a point of change. If in the mechanism shown

drehungs-Kurbel " (reverse-cranks), in the Civil Ingenieur, 1859, p. 99.
 * This mechanism was first described by Prof. Reuleaux, who called it "Gegen-

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