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An interesting take on the self-reversing nut.

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  • An interesting take on the self-reversing nut.

    I took this large piece out of a winding drum mechanism and had just had to take it apart to see how it worked. It's a cable winder and moves back and forth over about 8" whilst the shaft turns always in the same direction.



    The nut has three balls each set equally on 1/3 circumference. One is held captive, the other two are in slots but retained in position by spring clips. The steel cover ring has grooves in the ID to allow the spring clips to rise slightly. Here are the three balls installed in the nut.







    It took me a while to figure out how it worked because each time I took the steel top off it looked the same then I sussed it out. When the direction of travel reverses at the end, the two balls in the slots swap ends by diving under the springs. Amazingly simple but very clever too. The middle ball drives the nut via the groove and the two outside ones keep position whilst the middle ball navigates the cross-overs. The only issue would be how to allow for reversing which is neatly taken care of by the use of the slots and spring clips.

    So neat I thought I'd share it.
    Last edited by Peter.; 12-11-2018, 05:42 PM.
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

  • #2
    Here I've marked on of the balls' position in the slot.



    Now I turn the shaft so the nut winds to the end and back to the middle and the ball has swapped ends.



    Pretty slick!
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

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    • #3
      That is pretty fascinating.

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      • #4
        Very fascinating. Thanks for showing that.
        Those humans are clever devils!

        I remember as a kid puzzling over just how my Pfleuger fishing reel reversed the line guide travel. Eventually curiosity forced me to tear into it to see how it worked. As I recall it had a little key or pawl that flipped about 90 degrees at the end of each pass. In other words it flipped from a NW-SE orientation to a NE-SW orientation.
        Lynn (Huntsville, AL)

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        • #5
          So... the thread/groove on the shaft pulls the nut along until it hits the end. At that point, the thread pulls the balls under the springs, which then align with the thread going the other direction, which pulls the nut along until it hits the other end, which pulls the balls under the spring, which aligns them with the thread going in the other direction... back and forth.

          Did I understand correctly?

          Only issue is that the springs set the amount of force that the nut could apply to whatever is riding on it. Too much drag and it would reverse direction prematurely. I wonder what would happen if the balls got out of sync?

          David...
          http://fixerdave.blogspot.com/

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          • #6
            That is a Norco Ball Reverser and they are made in standard sizes. I used them in hose reeling machines that I use to build that wound up a 230 ft long 1-1/2" ID rubber hose. They even had a little spring clip you could snap into the groove that shortens the stroke. They weren't too expensive and worked very well. Except for that little stroke clip if you needed it, it was about $50!

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            • #7
              Originally posted by fixerdave View Post
              So... the thread/groove on the shaft pulls the nut along until it hits the end. At that point, the thread pulls the balls under the springs, which then align with the thread going the other direction, which pulls the nut along until it hits the other end, which pulls the balls under the spring, which aligns them with the thread going in the other direction... back and forth.

              Did I understand correctly?

              Only issue is that the springs set the amount of force that the nut could apply to whatever is riding on it. Too much drag and it would reverse direction prematurely. I wonder what would happen if the balls got out of sync?

              David...
              You understand the principle but it never loses it's tracking. When it's travelling left the left ball hits the end and starts jumping under the springs. The nut is still being driven left by the captive ball. By the time the captive ball hits the switch back the first ball has reached the the end of the slot so starts driving the nut to the right. The remaining third ball is now dragged under the springs to the very left of the slot just in time to hit the switch-back and follow the nut to the right.
              Peter - novice home machinist, modern motorcycle enthusiast.

              Denford Viceroy 280 Synchro (11 x 24)
              Herbert 0V adapted to R8 by 'Sir John'.
              Monarch 10EE 1942

              Comment


              • #8
                Never seen anything like it, amazing ingenuity, the kind of thing a video is worth watching as it’s hard to imagine it in operation.
                The only self reversing nuts I’ve ever seen have been politicians and lawyers
                Mark

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                • #9
                  Wow, seen the title of this thread and figured it had to be concerning a individual on the forum. My mistake.

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                  • #10
                    Originally posted by boslab View Post
                    Never seen anything like it, amazing ingenuity, the kind of thing a video is worth watching as it’s hard to imagine it in operation.
                    The only self reversing nuts I’ve ever seen have been politicians and lawyers
                    Mark
                    I'll see if it will work without the steel sleeve on Mark. If it does I'll take a short video of it working.
                    Peter - novice home machinist, modern motorcycle enthusiast.

                    Denford Viceroy 280 Synchro (11 x 24)
                    Herbert 0V adapted to R8 by 'Sir John'.
                    Monarch 10EE 1942

                    Comment


                    • #11
                      wow. Thats very interesting. Thanks for taking the time to post. JR

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                      • #12
                        Originally posted by garyhlucas View Post
                        That is a Norco Ball Reverser and they are made in standard sizes. I used them in hose reeling machines that I use to build that wound up a 230 ft long 1-1/2" ID rubber hose. They even had a little spring clip you could snap into the groove that shortens the stroke. They weren't too expensive and worked very well. Except for that little stroke clip if you needed it, it was about $50!
                        Thanks for that Gary, I did a search and found a PDF which explains all about how they work with diagrams.

                        http://www.motiontech.com.au/wp-cont...tor-230712.pdf
                        Peter - novice home machinist, modern motorcycle enthusiast.

                        Denford Viceroy 280 Synchro (11 x 24)
                        Herbert 0V adapted to R8 by 'Sir John'.
                        Monarch 10EE 1942

                        Comment


                        • #13
                          The winding drum on the Wessex MK3 dunking sonar has one of these. The level wind on Penn multipliers is similar.

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