The linkage shown below was used as the input for the "Wild Wild West" mechanism.
The solid line circle is the handle and input for the "Wild Wild West" mechanism. Link 6 connects to this handle.
Reasons why this specific linkage was chosen:
1. Full rotational output motion: so it can drive the circular input motion of the "Wild Wild West" mechanism
2. Full rotational input motion: so a person, or a motor, can provide a constant velocity, full rotational input
3. Slider makes resulting motion of mechanism more complex (vs. having a pin joint)
However, simply using any mechanism that looks like this isn't enough, and additional requirements had to be met to acheive desired behavior:
- Length of link 2 must be larger than distance from grounded pin of 2 to pin of 4 so that link 4 undergoes full rotational motion.
2. 4 bar mechanism (which includes links 4,5,6 and the pin at 4 to the pin at 6) had to be a Grashof(P+Q>S+L) double crank (shortest link is grounded) so full rotation of link 4 results in the full rotation of link 6.
3. Of course, length of slider slot should be long enough so link 2 can undergo full rotational motion.