MISCELLANEOUS MECHANISMS 401 
y 
division on AB, and in addition the follower has given to it its corre- 
_ sponding radial (Fig. 643) or angular (Fig. 644) motions, The contour 
Fia. 6438. Fia. 644, 
of the cam is obtained by drawing a fair curve to touch the various posi- 
tions of the follower, as shown. The contour is therefore the envelope 
of the follower, as the latter reciprocates or swings, and at the same time 
revolves about the axis of the cam, the cam being at rest. 
It may be pointed out here that if the plane rotating cam is made a 
circular eccentric cylinder working against a flat-footed or slotted follower, 
Fig 6465. Fig. 646 Fig. 647. Fig, 648. 
as shown in Figs. 645 and 646, the mechanism becomes the equivalent of 
a crank and infinite connecting-rod. Also the circular eccentric cylinder 
(Fig. 647) working against the end of a bar, with or without a roller, 
which can reciprocate in the direction of its length, is the equivalent of a 
crank CP and connecting-rod AP. If the slot in the follower (Fig. 646) be 
curved to a radius AP (Fig. 648), the mechanism becomes the equivalent 
of a crank CP and connecting-rod AP. 
337. Cylindrical Cams.—<A cylindrical cam may be used to give 
reciprocating motion to a follower in a direction parallel to the axis of 
the cam. This form of cam may be looked upon as the plane sliding 
cam bent round to the form of a cylinder, or the plane sliding cam may 
be considered as the development of the cylindrical cam. 
Fig. 649 shows one half of one form of cylindrical cam, and an 
approximate method of designing it. The roller shown is conical, and 
its axis intersects the axis of the cam. To construct a cylindrical cam 
Eeetcally, the acting surface should be cut by a milled roller or cutter 
ving the form of the roller or pin which is to work on it, the axis of 
the milled cutter being made to move over the pitch surface of the cam 
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