Sorry I couldn't chime in sooner. The clamps do have a big nut on the bottom. After saying this it also seems like there is a spring mechanism also in the clamp. If you turn the lever just a bit before the clamp tightens to the frame the lever will automatically return to it's previous positon.
Maybe all conelock clamps have this. I don't know. If not maybe it's a partial spring assist or partial conelock. The spring in these clamps don't assist in tightening but aid a little when loosening the clamp.
In any case the clamps require very little pressure. I find just the use of my thumb against the lever is enough for both tightening and releasing the clamps. I really like having only three teeth on top of the clamp, easier to fit between the strings.
Again I'm not saying they are a true spring assisted clamp because you feel more pressure as you turn the lever more to tighten the clamp to the base. Like turning a bolt with a nut on the other end for lack of a better description. That would probably constitute conelock. There is however some spring action when loosening the clamp. Like I said earlier maybe all conelock clamps work this way.
Hope this helps.