Thanks to Manu Järvinen for sharing his original concept you can find here https://www.blendswap.com/blend/1629
It inspired me to make this kind of rig tutorial "How to rig pistons in Inverse Kinematic ?" I hope it help you in your animations!
If you download this model feel free to use it in your artwork, modifie it, play with it, share it!
Thanks for downloading!