Calculating Force Needed to Lift Load with Pickup Truck Crane

[m iket]

http://www.harborfreight.com/1-2-half-ton-capacity-pickup-truck-crane-1647.html

I bought this truck crane for my father. How could i calculate the force needed on the handle to lift a given load? I could measure it but I am interested in how the math is done. For simplicity i'll assume the weight of the crane itself and friction are negligble. The load on the jacks two different diameter pistons or on various point along the length of the boom are easy to calculate separately. What i can't figure out is at where they connect. The piston extends in a straight line, but also rotates back as the boom rotates. there's different angles that are non-perpendicular and changing so i don't know how to start.

 

[russ_watters]

You already asked this question and generated quite a discussion of it... Pointless to start a new thread. Locked.