# What is the compatibility equation   • I am not entirely sure of the compatibility conditions. looks like this for me.
deltal1 + cos (alpha) deltal2 = 0

could someone tell me if that makes sense or is wrong? thanks

• Do you assume that delta_L (right bar) = delta-horizontal_L (left bar)?

If so: I tried that at the beginning and the result was wrong for me ...
But now I cannot say with absolute certainty whether the assumption is fundamentally wrong ... maybe I just made a mistake somewhere.

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• moment equilibrium was wrong with me ...
... just recorded true to scale and then discovered the stupid mistake

• Moment equilibrium should look like this, shouldn't it?
F * a + N2 * (sin (arctan (d / e)) * a) = N * c
am I wrong there?
if that is correct then it is definitely due to my compatibility equation

• "F * a + N2 * (sin (arctan (d / e)) * a) = N * c"
so for me it looks like this:
F * a + N2 * (sin (arctan (d / e)) * b) = N * b
but it could be because the names of the distances are a little different for everyone.
However, all of them are the same length for me, except for the vertical part of the left bar

• Did that work for you?
what kind of compatibility condition do you have?
ED: you're right ... copied it wrongly

• I also have momentary equilibrium like this:

F * a + N2 * (sin (arctan (d / e)) * b) = N * b

Compatibility condition:

delta_L (right bar) + delta-horizontal_L (left bar) = 0

but can't get the right result ?!

• looks like we have the same problem

• I have the same with the compatibility. But also (probably) not true.

I would like to know if anyone has a correct result at all.

• Hello,

if 1 is the right stick and 2 is the left, then the compatibility is:
delta l2 = - delta l1 * d / sqrt (5 ^ 2 + e ^ 2)

and the MomentsGGW around A:
-S2 * d / sqrt (5 ^ 2 + e ^ 2) * b + S1 * b = F * a

typed it in and it fits.

• with d / sqrt (5^ 2 + e ^ 2) do you mean generally d / sqrt (d^ 2 + e ^ 2) or?

• you only took the horizontal part for S2 at moment equilibrium (with my formula the same had to come out)
in principle, your motto is the same

• The equilibrium of moments is clear, but how do you come up with the compatibility condition?

• Original from AndiBar

if 1 is the right stick and 2 is the left, then the compatibility is:
delta l2 = - delta l1 * d / sqrt (d ^ 2 + e ^ 2)

Thanks!! If the right stick lengthened and the left shortened, I should already write "* d / sqrt (d ^ 2 + e ^ 2)" on the right side .. omg

• Thanks !! Had the same mistake
Ed: here also a program for the solution

### Files

• How do you approach the compatibility condition?
About a difference in height between the corner points, similar to the ZÜ? Or a twist?

• The change in length from the right bar must be equal to the horizontal change from the left bar

• ChristianL:
but it has to be d / sqrt (d^ 2 + e ^ 2) instead of d / sqrt (e^ 2 + e ^ 2) called or?

• Yes of course. Sry, I guess I got it wrong.

• what a shit .... sin (arctan (d / e)) was on the wrong side the whole time too ....

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