problems

320.000 11.200
340.000 2.800
- 369 -
360.000 0.000
To lay out the cam, first draw the prime circle which has a radius of 2.0" + 1.0" = 3.0". Next draw
the pivot circle for the follower pivot. The radius of the pivot circle is 4". Draw the follower in the
initial position ( = 0˚ ) to determine the follower length (r3) and the position on the pivot circle
corresponding to = 0˚ . As indicated in Example 8.5, the length r3 is given by
r3 = r1 2 (rb +r0) = 4 2 (2 +1) 2 = 2.646"
Identify the point on the pivot circle corresponding to = 0˚ , lay off the radial lines at 20˚
increments from this point, and label the lines in the counterclockwise direction. Draw lines from
the intersections of the radal lines with the pivot circle tangent to the prime circle. Then lay off the
angular displacements from these tangent lines. Locate the center of the follower by the distance r3
from the pivot circle along these lines. Draw 1" radius circles through the endponts of the distances
layed off along these lines, and fit a smooth curve which is tangent to the circles corresponding to
the roller follower.
The cam profile is shown in the following figure.