Need help with dynamic blocks and chaining linear stretch with rotate action

I am designing a suspension for a piece of agricultural equipment and would like to model the range of motion in the suspension. It is made up of an air bag that is fixed to the frame and only has a linear range of motion. The bottom of the air bag is connected to the gauge wheel via a turnbuckle. The turn buckle is mounted on pivot points at both ends. I have my block set up to stretch the air bag, but cannot get the linear stretch to trigger a rotate action on the wheel / turnbuckle. It only moves the grip of the rotate. I am using the stretch as the primary with the rotate action as the secondary.

I have tried using the rotate as a primary to trigger the linear stretch (which it does) but I get unexpected results. When the rotate moves the linear stretch, the air bag does not stretch in a linear fashion. It gets pulled out of shape by the rotate (like it is doing a polar stretch instead of linear).

I have attached my block for review. Is there anyway that I can model all of the interactions at once?

I'm using autocad 2007.

I'm sorry but I can't see your block. I have a bracket on a turned off layer and a polar stretch action linked to a distance but that is all. Should I have more?

Strange. I see what you mean. Let me try again. The model tab is blank. You will have to insert the block. It is called "air bag".

ddsusp2.dwg

ok, I can see what you want to do but I think it is beyond the capabilities of 2007/2008. 2010 does include parametric restraints which I think is what you require but as I don't have 2010 I can't comment with authority.

as a comment, I wouldn't have had the distance1 parameter. You can delte that and then re-associate its stretch action with the main distance parameter.

ok, I can see what you want to do but I think it is beyond the capabilities of 2007/2008. 2010 does include parametric restraints which I think is what you require but as I don't have 2010 I can't comment with authority.

I've been doing some reading and believe you are right. Oh well, I've come up with a "good enough" solution. I've broken it into three parts. Linear stretch on the bag (moving the turnbuckle with it), a polar stretch on the turnbuckle, and a rotate on the wheel assembly. Stretch the bag first, then rotate the wheel so it is approximately lined up with the turnbuckle, and finally stretch and rotate the turnbuckle to reconnect with the wheel assembly. My ultimate goal really is to just be able to explore how far up and down the wheel will travel as the suspension works.

as a comment, I wouldn't have had the distance1 parameter. You can delte that and then re-associate its stretch action with the main distance parameter.

Great point. Thanks for the input. I've been doing a little reading and learned that I can associate multiple actions with a single parameter, but was only thinking that it could be done with rotate actions. I didn't think about stretch.