Lever Arm Question

[ApexM0Eng]

I have attached a picture outlining a setup that I have a question about.

In this setup, there is a load that is being tilted around a pivot point. It's center of mass is located a bit off body, shown by a dot in the picture labeled CM.
Space being an issue a proposed solution was to extend a tab from the pivot point and pull from it using a linear actuator.

I would like to extend this problem such that if anyone can see any major downsides & issues with this setup that they might share them.
If anyone would like more information, it can be provided as requested.

 

[ApexM0Eng]

We have changed the geometry of the arm a few times now, removing material where we can to reduce the overall weight. Now instead of pulling from the bottom lever, we have room to push from the right of the arm itself. It means a longer stroke actuator and pushing further from the pivot.

As for the product. It has negligible weight compared to the container that is moved holding it, and the arm holding the container. I really didn't like the forces I saw with the original system. However. there is more inertia with the Counter Weight and doubling the mass of the system to get the CM at the pivot might not be worth it. I am informed that we had air cushions helping before as the CM went over the 90°, so we had back pressure helping before.

So next question: If instead of using a large counter weight to pull the CM back to the pivot, I used a smaller CW facing down to pull the CM at 90° to the pivot, would that solve issues with the CM going over the pivot in the last 20° of the 110° arc? Such that at the top of the front cycle the CM would be directly vertical to the Pivot.

 

[dvd]

How many times are you going to perform this operation?

If the answer is a lot of times then look at a rotary indexer with rigid couplings - you are going to bang the heck out of that contraption slamming into cushions on cylinders.

http://www.camcoindex.com/ID_PARA.HTM

 

[ApexM0Eng]

18 cycles /min . 5 hours a day . 5 days a week.

I really do like the idea of a rotary indexer, there simply isn't the room for one. In addition cost becomes an issue too. The cylinder might cost us 80$ and be over designed by x8-12.
Rotary motion means gearbox, servo, wires.
I think if the project allowed to flip the product and have a next indexed set of arms ready for another, it would be great.

Still, this exercise has shown that a counter balance reduces the overall force on the cylinder and would be a good option for certain future projects.
It also allowed us to redesign the arm such that the Center of Mass did not move past the vertical.