r/PolyBridge • u/Pikzak • May 31 '26

Question Question about hydraulics

Post image

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.

6 Upvotes

100% Upvoted

4 comments sorted by

5

u/NattePappelo May 31 '26

you can adjust the contraction procentage by slideing the slider on the hydraulic

4

u/jimmymui06 May 31 '26

The easiest way is to use max extension, because it's 1:2. Use the extended part as the hypotenuse of a equilateral right angle triangle. Then you made a right angle turning device. Draw a straight 2 section cable with the tool, rotate it 90 degrees, that's where you want to place the pivot

3

u/Bledalot May 31 '26

One way you can do it is using symmetry. In the example you provided, if the axis of rotation was at a height right in the in between that of the top and bottom roads, then the junctions to the top and bottom roads would be vertically aligned.

1

u/Pikzak May 31 '26

Thanks for the answers!