Page:The Kinematics of Machinery.djvu/474

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KINEMATICS OF MACHINERY.

114 -

Friction- wheels ; Belt and Rope-gearing.

.Friction-wheels are kinematic elements in force-closed pairs. Two corresponding wheels, such as those of Fig. 313, arranged so as to work in gear with each other, form a higher pair of elements of the form JB+,.R+ or R+ t E~.

FIG. 313.

FIG. 314.

A pulley which guides a cord or belt, or by its rotation sets such an organ into motion, forms with it the pair R + > T> as in Fig. 314. Two such pairs (which are, as we know, force-closed), when suitably united, give us the belt.- or rope-train (as the case may be) shown in

Fiu. 315.

Fig. 315, if the shafts of the pullies and the connecting frame be added (cf. 44). The single rope-wheel or belt-pulley or drum forms with its shaft a link of the chain represented in the figure, the " endless " tension organ being itself another link.