formula for lifiting hinges ?

[dogscats]

Home made hinges there a formula to make these parts .I think this would work for a lifting roof . DO you know of one.
Dose not seam hard to build.

[WizardOfOdds]

Thanks for posting the great picture. Who made them??

From the very limited observations I have had, I think this design was used for at least some of the old VW camper roofs that hinge at the rear. I also think I have seen it used for truck doors on cars. The thing I like is that it that there is at least some minimal rise on the hinge end of the roof (a conventional hinged roof has no rise at the hinge pivot).

One concern: I see the hinge to be sensitive to lateral torque. Notice the hinge comes to a small overlap at the crossing point of the two long arms. This small overlap is the only resistance to twisting torque. Granted there will be a second hinge on the other side, but it is still possible for the roof to twist rather easily in a heavy wind.

As far as equations go, I find it helpful to reduce arms to just lines with pivot points. For simplicity, assume you know all the link lengths and want to find the angles when opened and closed. Then break the hinge into lower and top halfs (at the cross point). Then analyze just one half at a time.

When you do, you notice that the two extreme states (fully closed and max open) are just triangles. That makes analysis of the extremes just simple triangle trig. In the fully closed position the small link will be aligned with the stationary base line. This tells you that the sum of the two X bar half lengths must be at least the base plus the small link (the so-called triangle inequality).

In the fully raised position, the small link aligns with the x-bar it is connected to. In both extremes, we know the length of all three sides of each triangle, so you can us the “law of cosines” to calculate the angles.

I hope that helps.

[dogscats]

These where meant to replace WV hings. Sadly a few years ago . found a program on the web that you input how high you want the lift to be .Then it show how to make . Now that I am thinking of building . Can't find now.
I fond a picture of where there doubled up but wont down load. That help with twist.

Who made them

In the picture it show Flint . No luck finding more.

THANK YOU WizardOfOdds for the post .That will help