Hey guys, I'm trying to design a reciprocating pump engine with a dynamic stroke length. basically something like this: http://www.animatedsoftware.com/pics/pumps/animpist.gif" [Broken] However I wish the stroke length to be variable and dynamic. The only way I have found so far is the change the r value from the origin of the wheel to the connecting rod. The issue I'm running into is one of balance. If I use a linear actuator or some such to change the r value the wheel will not be balanced and cause vibration. anyone else got any ideas?