Design a four bar linkage where the rocker length is between

Design a four bar linkage where the rocker length is between 5 inch and 6 inch with a swing angle of about 60 degree. Also the time ratio of the linkage is required to be between 1.5 and 1.75.

Solution

I will suggest you take the mean of the values and design the four bar linkage

Rocker length=5.5in

Time ratio=1.625

Or you can consider it as double rocker mechanism in which sum of lenght of smallest and longest link is greater than sum of other to links