Page 565 - Dynamics of Mechanical Systems

0593_C16_fm Page 546 Tuesday, May 7, 2002 7:06 AM

546 Dynamics of Mechanical Systems

FIGURE 16.6.2
FIGURE 16.6.1 Contact between cam and follower at a typical cam
An offset flat-surface follower. orientation.

FIGURE 16.6.3 FIGURE 16.6.4
Cam profile with superposed radial lines. Representation of the follower at various positions
about the cam profile.
If, as before, we attempt to determine the follower rise function (assuming constant cam
angular speed) by considering equiangular radial lines, we see that, due to the offset, the
follower axis will not coincide with the radial lines. Also, due to the flat follower surface,
we see that the base of the follower at the axis of the follower will not, in general, be in
contact with the cam profile (see Figure 16.6.2).
A question that arises then is how do these geometrical changes affect the graphical
construction of the follower rise profile as in Figure 16.4.3? To answer this question,
consider again constructing radial lines on the cams as in Figure 16.4.3 and as shown
again here in Figure 16.6.3.
Next, for each radial line let a profile of the follower be superposed on the figure such
that the axis of the follower is parallel to the radial line but offset from it by the offset of
the follower axis and the cam axis. Let the follower profile be placed so that the flat edge