CHAPTER XXV 
MISCELLANEOUS MECHANISMS 
333. Cams.—A cam is generally a rotating piece which gives a 
reciprocating or oscillating motion to another piece called the follower, 
the contact between the two being line contact. A cam may however 
have a reciprocating or oscillating motion as well as the follower. 
$34. Motion of the Cam Follower.—In general the cam follower has 
either rectilinear motion or angular motion about a fixed axis. Figs. 627, 
629, and 631 show cam followers having rectilinear motion, AB being the 
Fig. 627. Fie. 628. Fia.629. Fie. 630. Fia. 631. Fig. 632. 
length of the travel of the follower. Figs. 628, 630, and 632 show cam 
followers having angular motion about a fixed axis O, the amount of the 
movement being the angle AOB. 
The velocity of the cam is generally uniform, but the velocity of the 
follower is usually variable, so that equal movements of the cam are not 
accompanied by equal movements of the follower, and in designing a cam 
the first step is to assume equal movements of either the cam or the 
follower, and then, from the given conditions, to find the corresponding 
movements of the follower or cam. 
Whether the motion or displacement of the cam be rectilinear or 
angular, it may be represented by a straight line. Let AC (Fig. 633) 
represent the displacement of the cam during the time that the follower 
travels from A to B and 
Gckiaghin to A. Divide *%§ r— , 
AC into any convenient 48 
number of equal parts, say 349 
twelve. These parts will 2+ nw 
represent equal intervals of os ; : 
displacement of the cam, "A0 23456769 ONC 
and if the cam is moving 
with uniform velocity these 
parts will also represent equal intervals of time. Let it be given that 
during the lst and 6th intervals the follower is to remain at rest, 
that during the 2nd, 3rd, 4th, and 5th intervals the follower is to 
Fig. 633. 
