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.
�
