Page 223 - Robotics Designing the Mechanisms for Automated Machinery

6.2 Linear Transportation 211

Thus, the pitch of the movement equals the pitch of the chain or the length of one link.
In some cases the pitch of the movement equals some whole number of chain pitches.
This is illustrated schematically in Figure 6.7. To drive chain 1, drum 2 must be driven.
The simplest way to do so is to use an appropriate kind of Geneva mechanism (see
Figure 4.1). A strict ratio ^/T^ is typical for these mechanisms. Indeed, let us suppose
the driven link of the mechanism has z slots. Then, as it follows from the sketch shown
in Figure 6.8 (this is an instantaneous look of a Geneva mechanism at the moment of
engagement between a slot and driving pin), we can write

and

From Expression (6.5) we obtain

and, taking into account (6.3), from (6.6) we have

FIGURE 6.7 Design of a chain-type
conveyor for periodic automatic
processing.

FIGURE 6.8 One slot of the Geneva mechanism engaged
with the driving link of the mechanism.