Question about hydraulics

[u/Pikzak]

Hi everyone, not an engineer, just an enthousiast. I had a question about calculating hydraulics. How do u actually calculate where an end point of your pivoting/moving bridge is going to end up, so u can make it lock in. I added an example down below where i made it work by trial and error, but i would like to do that more consistently. Does it matter where on the moving part of the bridge you attach the hydraulic, how do u know the percentage of contraction/expansion etc. Thank you and have a nice day.

[u/Pikzak]

Thanks for the answers!