Page:The Kinematics of Machinery.djvu/562

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�KINEMATICS OF MACHINERY.

�cylinder itself here becoming a screw ( 15). Higher screws S, are not unfrequently paired with T, the fusee of a clock or watch^ for example, Fig. 372, or the conic rope-drum which has lately been much used in winding engines, or the fusee in Eobert's mule, Fig. 373. The conoid with a rope enveloping it (Fig. 374) belongs also to this class. The order to which these pairs belong is therefore (/S, t ), under which the class (, t ) is a lower form. At

���FIG. 373.

�FIG. 374.

�the limit S = E we obtain the group (E }i ) of which Fig. 375 shows two examples.

The next order is furnished us by the pairing of T with H } the pair being therefore (H, t ). As a representative of the class ((7, t )

���FIG. 375.

we have the pair formed by a rope-drum and a flat belt laid spirally round it.

With H s we can pair the chain T v It gives us the order of which there are many applications.

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