I should say that while I've taken some physics courses, I should probably be considered a layman or hack as I haven't done any real world engineering. I'd love to hear some more expert feedback on this topic. I'm sure that there are many approaches to this concept. For this project, my goal is to find an elegantly simple, low maintenance system that is also rugged, shock-resistant and relatively low cost. I prefer a solution that is passive requiring no external power supply but this may not be possible I understand. Other constraints: -Dimensions - Total height of the outer box/cage can't exceed about 10". The shorter the better. width and length of inner box determined by external factor and not defined yet. -Wear resistant materials a plus for low maintenance. -Preferably non-conductive (electrically) or reactive materials. Inner 1000lb box is probably going to be an aluminum box. This is what I have initially come up with. Excuse the crude mock up conceptual drawing here: https://docs.google.com/drawings/pub?id=1MlW0PVnVVYXUagx5tbkW_IEL7lKHZDRBCleXSrojRLY&w=960&h=720 Questions I have: What is the best possible latency in the restorative force I could expect in a hydraulic system like this? Are ball bearings best for low friction and low clearance? Are plastic/synthetic ball bearings rugged enough for this weight? Am I totally missing some basis concept here? Does this idea make sense? Is electronic control necessary to have a more responsive system, ie: less latency? I considered a robotics approach, using gyroscope etc, but again, was hoping to solve this in a purely mechanical fashion, ie: the "dumb" way. Thanks for your comments.