Parametric Mobile Crane, Hydraulic RAM constraint problems any ideas ?

[glenn.royds]

My Sunday morning REVIT Project. I'm part way through creating a 5 wheeled mobile crane loosely based on Leibherr LTM1100 5.1. The model is fully parametric and I have managed to nail most parameters, boom angle, rotation, extension and hook drop, leg stabilizer movement and foot etc.. but failed on the main Hydraulic Ram behaving properly. Its no deal breaker but I would like it to behave as the real thing.

The model consist of several families nested and hosted of reference faces and planes

I have hit a brick wall constraining the main Hydraulic Ram at either pivot as it gives me an errors or breaks. I cannot drive it with just and angle as its a rising rate linkage and therefore not a linear progression (if that makes sense?).

I would like to use something like an adaptive family so either end of the ram follows the pivot locations 

I'm sure the solution is simple but I've tried multiple ways and my brain is now fried. Anybody got any cool ideas ?

The crane is attached hosted in a dummy project if you guys wanna have a play at driving cranes or reverse engineer it.

Here is the pivot offending lower pivot point in question. The Ram end needs to follow this lower pivot while still following the upper pivot

Many Thanks in Advance.

Cheers

Glenn

[barthbradley]

Isn't this ram assembly supposed to move and pivot in relation to the boom angle?  If so, I'd model this parametric assembly in a  separate family and nest into the boom family and then associate its parameters to boom family parameters driven by trigonometric formulas based on boom angle.  

 

[glenn.royds]

Thanks for the reply, the Luffing Ram (I think that's its name) has two fixed points, I'm trying to figure how to constrain the Ram to these two points and adjust its length. I've done this ages ago in 3DMax modelling a crane  however Max has a "look at" function so it was easy for the ram to always point at the pivot. I was trying to see if I can constrain either end of a reference line to these point at the pivot locations but to no avail you can only constrain one end.

As suggested I have now made the nested cylinder assembly with a parameter for length and hosted it on a reference line just need to figure the rest.

Cheers