Putting Linkages Together

How high a load?

Are you making excavators or camcorders? both are excelent examples of linkages IMO. Camcorders, VCR, ect use rather complicated linkages with many metal stampings for links. Usually they are riveted together or ocasionaly have tiny shoulder bolts. If that is the type of product you are working with I would strongly suggest tearing one apart and study thier linkage systems. I tried to reverse engineer one a while back, and it's tough to graph out the profiles of all the links at different stages of the crank (or pinion gear on rack) angles.

On the other end of the spectrom is excavators, specificly the four bar linkage at the bucket. I think the buckets rotate through over 180 degrees; that's pretty good given the loads and using a linear actuator (hydraulic cylender.)

Somewhere in the middle with a high load and frequency demand is automotive stearing linkages. These use mostly rodends or ball joints. Study these things.

Google is your friend.