Calculate forces on a double scissor jack

[Bohr1227]

Homework Statement

Find maximum forces in one given jack assembly. If I don't make it any easier, I will have 15 unknown forces, so I tried to just take the weight forces at the top...is it an okay assumption? If not, what should I do? My attempt on a solution is underneath. Thanks for tips and answers.

Homework Equations

They are given in the picture below.

The Attempt at a Solution

 

[Nidum]

There have to be balancing forces somewhere - the stand as shown would just collapse .

Do you want to work out the forces in each link or just the ratio between input force and lifting force ?

Have you seen this earlier thread ?

 

[Bohr1227]

There have to be balancing forces somewhere - the stand as shown would just collapse .

Do you want to work out the forces in each link or just the ratio between input force and lifting force ?

Have you seen this earlier thread ?

I'm sorry, I have a motor that holds the bar between the jacks together, so it is a force F holding the lower right leg in place. I'm most interested in finding where and how big the maximum stress is, so I can choose the right cross section for it.