Sliding Relative Motion

merrill.rosenow · ‎Jun 17, 2009

Hello everyone,

I am having a little trouble properly modeling a mechanism. Basically, it is a telescopic square tube with multiple segments. I want the different segments of the assembly to proportionally extend to their maximum length when the assembly is at its full length, and their relative length to be zero when the entire assembly is collapsed.

I have never made a mechanism like this. First I took the component that would be furthest from the base and made that the mechanism. This allows the component to be dragged. I then made an analysis measuring the distance of extension. I then added the other telescopic components and made a relation so their distance from the base was proportional to the overall length. The problem is, this does not dynamically update. You have to manually regenerate the assembly after moving the furthest most piece.

I was under the impression there was a gear option I could use to make this type of assembly. Unfortunately, in my WF 4 dash board, I was not able to find that option. I only have rigid, pin, slider, cylinder, planar, ball, weld, bearing, general, 6DoF and slot available to me.

Where do I go (and what is it called) to make a dynamic mechanism that keeps these segments at a proportional length?

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JWayman · ‎Jun 18, 2009

Hello,
I had the same trouble a while ago and got loads of help from this exploder.
In a nutshell, you need to use Mechanism Design Extension, and you need to
create rack and pinion gears between the sliding elements.
In WF2, you have to select the 'Tools', 'Applications' menu and choose
'Mechanisms'.
The connections you describe are those available in the base application.
Again, in WF2, gears are only available in MDX.
Then, when you drag any section other than the bottom, they all move
correctly.
I hope that all makes sense.

Regards,

John

merrill.rosenow · ‎Jun 22, 2009

I did try to create this gear pair before. The problem is that the telescopic assembly slides past each other, and has no axis for the "pin" to rotate around. Do I make an arbitrary axis outside of the assembly, and have the mid-section of the assembly reference their own gears off of this for the relative motion?