I want to use a motor to drive a lead screw that first brings down a platform that locks into place and then controls a secondary platform to apply pressure but using only a single motor.

As an example use two nuts on a linear drive screw. Nut A would contact a physical barrier and not move further while nut B would continue moving until it contacts Nut A. This should be reversible.

I am sure I have seen a similar system on some cnc machines and such but am unable to identify a working mechanical mechanism or model that can accomplish this.

Can anyone identify a system that could perform this or similar mechanism?

  • $\begingroup$ Why not something like a toggle clamp actuated by a lead screw? $\endgroup$
    – TimWescott
    May 2 at 20:41
  • $\begingroup$ It may be helpful if you could edit your question with information about whether the thing to be clamped is always the same (i.e., is it a production fixture) or is always changing. $\endgroup$
    – TimWescott
    May 2 at 20:42
  • $\begingroup$ I'm not able to edit the question through the app. But the item to be clamped is always the same. $\endgroup$ May 2 at 21:21
  • $\begingroup$ Any chance you could draw (and post) a picture of the two platforms and how they should move? Maybe I'm just slow, but I'm not sure I understand what you're really trying to accomplish. $\endgroup$ May 2 at 22:21
  • $\begingroup$ Depending on the forces you are dealing with, a friction clutch on nut A would do it. Or are you thinking about the anti-backlash nuts on CNC machines that don't do exactly what it is you are describing? $\endgroup$
    – DKNguyen
    May 2 at 22:34

1 Answer 1


I'm not entirely certain I understand what you're after, but perhaps this fits your requirements....

The lead screw would have threads with two different thread pitches. The platform would run on the fine pitched thread, and the clamp on the coarse thread.

So, at one extreme the platform would be lifted up, and the clamp lifted up farther.

As we drive the screw, the platform moves into position and the clamp (moving faster, since it's on a coarser thread) moves into position where it clamps against the platform (or probably something that's sitting on the platform).

enter image description here


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