Anyway, basic bone animation is:
- make an Armature (parent object for bones), probably want to be careful this and the object have the same origin at 0,0,0.
- add Armature modifier to the mesh, link that one
- make bones
- look at vertex groups (same tab as uvmap), make one for each bone (this bit's annoyingly not well connected, you have to manually type the name of the bone)
- ctrl+tab to go from object mode to weight paint mode (or in dropdown) and you'll be editing the highlighted vertex group
- easiest way imo is just use a gradient (alt+lmb) to set weights, just set "strength" to 100% and 'Add' to brush type on the tool ui first. You can tweak from there but gradient to me seems to be the only way to get all the vertices painted in the mesh (normal brushes have really awful ability to paint). Dark blue is 0 weight, red is 100% weight.
- select other vertex groups to do each bone
Armature editing just lets you start from the root bone and extrude (e) more bones, then you can go to pose mode (ctrl+tab from object mode) to see how the mesh follows it.
I believe you can also do armature animations aimed at Empties instead of Bones but no idea how to get that happening.
You could also leave the Armature modifier in "envelope" mode but that's meant for stuff with an actual skeleton, will automatically assign vertices to bones based on how close they are. I think for a leaf spring it'd be easier to just have 1 bone moving around and then a gradient of weights so it follows more closely towards each end.