Trebuchet pendulum...

[iacob alex]

.....at : http://www.geocities.ws/iacob_alex/Some_Drafts/text048.jpg
Simply , a "modified" old gravity throwing machine , playing variable leverage into a possible oscillatory self-running one...
Let's see:
-0*-180*/we have unbalance and rotation
-180* point/long arm moves as a short arm , due to gravity
-180*-360*/we have unbalance and the continuity of rotation
-0*(360*) point/short arm moves as a long arm , due to rotational inertia of the two bodies and heavy hub.
For this design,the only critical point ("problem" to test...) is the top position...it's a question of size and trebuchet's gained practice.
You can see it as an automat "non-throwing" trebuchet...
   Al_ex

[iacob alex]

.....as a proposal-design for a gravity motor (simple machine ) , can be minimized , in accordance with a natural model ("proposal"...) , if you take a look at :
  http://www.youtube.com/watch?v=uGBANgbRkws

So , we can play the barycenter on the same side of the fulcrum (semi-space) , with two masses only...
      Al_ex

[iacob alex]

.....as a possible theoretical introductory "input" for our topic , at :
  http://www.uark.edu/ua/pirelli/testing/Unit2/CMwBang!10.htm
  Read it carefully...as a particular point of view.      /Al_ex