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494 CAM DESIGN HANDBOOK

FIGURE 14.44. Cam-modulated mechanism—noncircular gears
(printing press transfer mechanism). (Courtesy Michle Printing Press
and Manufacturing Co., Chicago, Ill.)

action in which a dwell period cannot be fulfilled by meshing gears alone, since the driver
and driven gears must always move.
In Fig. 14.44, the follower is shown accelerating clockwise. Cam 1 and roller 1 are
employed for the initial dwell range into the positive acceleration portion of the action,
with cam 2 and roller 2 used for the negative acceleration portion to the dwell period. The
gears mesh between these ranges of action. Note that conjugate cam mechanisms are
utilized and backlash is kept to a minimum; see Peyrbrune (1953).

14.28 CAM COMPUTING MECHANISMS

Computing mechanisms are devices that solve problems automatically and quickly and
are classified as either digital or analog computes. Computers today are universally of the
digital type. This section is an introduction to cam analog computers, which could be of
value in the recently emerging field of micromachines of (Chap. 15). The most complete
survey on analog computers is by Svoboda (1948) and Fry (1945).
An analog device is one in which the numbers are changed into physical quantities
(voltage, gear revolutions, etc.) that are related; they perform the mathematical operation
which is translated into digital form. In the analog computer, the precision of the calcula-
tion depends on the precision with which the device is fabricated and read on calibrated
scales. It is often a cam-modulated system comprising bar linkages or cams, separate or
in combination, together with gears, lead screws, and other mechanical members. Applied