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Model Auto-Reversing Winch

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  • Model Auto-Reversing Winch

    I'm a bit early into the game here, but far enough to share a concept. Last year I designed and built a mechanism that would reverse a flat belt drive, in order to mimic the reversing of a belt drive from a line shaft. It worked. It was rather crude and "sorta" worked but after making a couple of videos of it in operation it has set on a shelf in my office and never been touched again. However--there was a little bit of magic at work there, because when the lower shaft was driven by a motor, the two semi transparent drums turned in opposite directions. Now, imagine a winch drum that sets between the two outside drums and is not keyed to the shaft. It is actually a bit narrower than the space. Think "dog clutch". If I had a mechanism that would slide the drum to the left or to the right, it would rotate clockwise when forced up against the driven drum on one side, and counterclockwise when it was forced up against the other drum. Now think of two mechanical "bobs" attached to the winch line, that contact an arm at maximum height and forces the moveable winch drum against the opposite driven drum. This reverses the rotation of the winch drum and pays out line until at minimum height the second "bob" contacts the same arm and swings it over against the other driven drum. There won't be enough force to make the faces a friction drive. It will have to be a dog clutch that engages very easily. Will share more with you fellows after I have thought this out a bit more clearly in my head.---Brian
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

  • #2
    I have worked out all the design of the self reversing winch. When the "bobs" on the string hit the arm which is attached to the bevel gear, the bevel gear rotates (only a little bit) and causes the second bevel gear to rotate. The carrier rotates (again only a little bit) and the bearings attached to it cause the winch drum to move to either the right or to the left. As soon as the winch drum rides up against either semi transparent drums, the built in dog clutch (which you can't see in the models) engage and turn the winch drum either clockwise or counterclockwise until the other "bob" attached to the string hits the arm and moves the winch over against the other drum which is rotating in the opposite direction.


    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

    Comment


    • #3
      I've been rethinking this mechanism. This picture shows the current state of what I am starting with. I have spent a few hours this morning rethinking the design to let me use more of the parts that I already have. The model shows my change in design direction.

      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

      Comment


      • #4
        Not related exactly, but....
        Ya know what I think is a cool mechanism?
        The works inside those Zero-Max variators.
        It is like 2 crankshafts with an adjustable stroke.
        When the strokes are the same (or maybe in phase, I can't remember)
        it has input motion. And to follor suit, when one stroke is different
        (again, maybe the crank phases change) the output speed changes.
        What I do remember, is that once I took apart a Zero-Max, because
        it stopped working, and there were so many plates and washers and
        springs, it was really something.

        --Doozer
        DZER

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        • #5
          DZER

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          • #6
            Brian - my only thought about the 2nd option would be how much leverage would the bobbin/ string be able to exert on the rack and whether or not the arm driving the rack would be stiff enough to direct all of the bobbin's movement into moving the rack.

            Comment


            • #7
              I've never seen a Variator. I have shortened up the offset arms as much as I could without blocking the space directly above the winch drum. The "bobs" on the string will have adequate power to shift things when it is being reeled in. When it is being paid out, the only force will be from the weight of whatever load it is lifting.
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

              Comment


              • #8
                That looks nifty. I am not sure what it would be used for, but it looks nice. It would run something up and down, cycling back and forth continuously. A bucket in a well?

                Another mechanical way to do this would be with a tumbler reverse mechanism like we use on our lathes to reverse the lead screw. That way, the cable drum would not have to be moved on it's shaft. And it would probably need less force to activate that tumbler reverse than what is needed to slide the drum which may be under a heavy load. You did say this if for a winch, which is a device for generating a significant force in the cable to move a load.

                Not to rain on your parade, but wouldn't it be easier and a lot more reliable to use a motor that reverses and sensing, limit switches and solid state relays to accomplish the same thing.
                Last edited by Paul Alciatore; 09-12-2019, 04:47 PM.
                Paul A.
                SE Texas

                Make it fit.
                You can't win and there IS a penalty for trying!

                Comment


                • #9
                  Paul--the endgame is to have a hoist which is driven by my most recent hit and miss engine, to show it hitting and missing under no load conditions, and only hitting with no misses when lifting a load. I have a great video of that right now, but it includes me being there to engage and disengage the hoist. I'm just looking at a way to do this automatically without needing me. Actually, I'm doing it more because I'm bored.---Brian
                  https://www.youtube.com/watch?v=JRtmoje5uJA
                  Last edited by brian Rupnow; 09-12-2019, 05:29 PM.
                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

                  Comment


                  • #10
                    Today I made the winch drum and put the groove in each side that gives me the "dog clutch". The knurled round part setting beside the new winch drum is one of the original parts that has been drilled and had a piece of 1/4" shaft Loctited into it. (the other existing drum is laying at the front of the mechanism.) Due to the gearing, the two knurled drums rotate in opposite directions--they are locked to the shaft which is actually three individual shafts--right shaft fixed to right knurled drum, left shaft attached to the left knurled drum, and a floater shaft between the two which is not powered. The winch drum is shifted from one side to the other to reverse it. There is going to end up being a very small gap between the winch drum and the 1/4" shafts that are mounted in the existing knurled drums because the winch drum must not engage both drums at the same time.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • #11
                      OoOooK! I do understand. Have fun.



                      Originally posted by brian Rupnow View Post
                      Paul--the endgame is to have a hoist which is driven by my most recent hit and miss engine, to show it hitting and missing under no load conditions, and only hitting with no misses when lifting a load. I have a great video of that right now, but it includes me being there to engage and disengage the hoist. I'm just looking at a way to do this automatically without needing me. Actually, I'm doing it more because I'm bored.---Brian
                      https://www.youtube.com/watch?v=JRtmoje5uJA
                      Paul A.
                      SE Texas

                      Make it fit.
                      You can't win and there IS a penalty for trying!

                      Comment


                      • #12
                        Killjoy!



                        Originally posted by brian Rupnow View Post
                        ...<snip>...

                        because the winch drum must not engage both drums at the same time.
                        Paul A.
                        SE Texas

                        Make it fit.
                        You can't win and there IS a penalty for trying!

                        Comment


                        • #13
                          The reversing winch mechanism is finished. It operates very smoothly on the test bench. The pivot for the gear segment got changed from a shoulder bolt to a 3/8" shaft with ball bearings, to prevent binding at the pivot. Tomorrow I will do a dynamic test. If it is successful, then I will post a video.
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

                          Comment


                          • #14
                            I think I am going to have to add a counterweight to the other side of the gear segment axis. I have tried to make everything very "free" so that nothing will bind. I've succeeded so well that the weight of the offset arm makes the winch drum change sides.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • #15
                              This morning was the first "trial run" of the system, and I am quite happy with the results at this time. The winch drum does reverse as I had hoped, and does so quite smoothly. I am going to add something similar to a ball indent pin to hold the mechanism in forward or reverse gear so it doesn't move from vibration as it runs. Thanks for having a look.---Brian
                              https://www.youtube.com/watch?v=BpDmpUL3wIc
                              Brian Rupnow
                              Design engineer
                              Barrie, Ontario, Canada

                              Comment

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