please explain

[eloid]

what is the advantage / disadvanage of Double nut, preloaded, (2 dual circuits) and just preload ball screws

[nwrepair1]

Double nut usually has a way to adjust preload. They are two single nuts combined. Single nuts can have oversize balls in them to take up slack and create a preload. Advantage of double nut is that you can adjust them, but they are more expensive.