Page:The Kinematics of Machinery.djvu/580

 558

�KINEMATICS OF MACHINERY

�If the link c in such a chain be made infinitely long we obtain the chain shown in Fig. 404, which also finds a number of applica- tions. Its formula is (O r S C- L P+C+).

If now the length of the link e be also made infinite, or in other

��FIG. 405.

words the axis 5 removed to an infinite distance, the chain takes the form shown in Fig. 405. The varying angle between the links ~b and c in Fig, 404 has here become constant, the cylinder pairing at 3 is therefore superfluous, and we obtain the four-linked chain which we may call a skew screw-chain. Placed upon

��FIG. 406.

d it has received a very neat application by Nasmy th in his dividing machine.* Fig. 406 shows the arrangement adopted by him. The frame d is here the bed of the dividing machine and c the slide. The angle between the pair 3 and 4 is made variable, so that the motion of the slide for each revolution of the screw can be altered with great nicety within very wide limits.

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