[masklinn]

Crane counterweights are a completely different matter. The crane doesn't have to drop the counterweight to take on load (the opposite really, unless it's a superheavy with active counterweighting the entire point is to be more stable once loaded).

So the issue with this thing is, any time you move an actual load from A to B, you need to have a weight waiting for you at point B. Or to offgas at which point you won't be able to make a second trip without regassing.

[joenathanone]

If the weights remain on the ground you can use a pulley system to load and unload weight, just put slack in the cable and lighten the load… Could even be automated with the right sensors.