Announcement

Collapse
No announcement yet.

Options for a one way longitudinal clutch

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Options for a one way longitudinal clutch

    Just using the picture I found on the net as an example, but say I have a round or square bar in a hole in a block. Other than a rack and pawl, or a jam lever like the bar on a caulking gun, what are any other options for that bar locking in any given position in the block when forced backwards. Is there any off the shelf type of one way longitudinal clutch I can fit on? Or am I not seeing the obvious here?





    Last edited by junkaddict; 10-07-2020, 12:05 AM.

  • #2
    This reminds me of the Premier timpani (kettledrum) I rebuilt for a local choir a couple of years ago.

    Timpani are tuned by a pedal mechanism, often in the middle of a piece. For example, I am playing timps next month in a piece which requires me to re-tune seven times during its course.

    IIRC, the mechanism is a spring-loaded rod running more-or-less vertically through a tapered hole in a block. The hole has steel balls in it surrounding the rod. Push on the toe of the pedal and the rod moves down, pulling the six arms that tension the hoop around the drum-head's rim with them, tightening the tension on the head and thereby raising the pitch. Releasing the toe-pressure on the pedal without allowing the pedal to move up or down allows the tapered hole to push the balls against the rod, locking it in position.

    Pushing on the heel of the pedal moves the block so that the balls no longer lock the rod, which is then free to move up again from the spring tension, under the control of the pedal, thus lowering the pitch of the drum. When you arrive at the right note, just lift your foot off.

    It's a simple but very effective trick. It should be pretty reliable—the one I fixed had just locked up from lack of use. It was an interesting voyage of discovery determining how it worked.

    Comment


    • #3
      What you are wanting may be a 'backstop clutch' but in looking all I seem to find are for rotary shafts. So if you have some rotary drive for this linier motion then one of these may work. Are we to assume that you will want to release this so it can travel in the opposite direction? A few more design parameters will help us help you.

      lg
      no neat sig line

      near Salem OR

      Comment


      • #4
        Linear brake ?
        Make a Tapered hole (less than 7 Degrees) and then make a collet with a matching taper.
        The collet should be for your shaft size and be split into say 4 pieces and mount a spring on the discharge side that puts pressure on the collet segments
        Your rod will easily feed out, but the collet will prevent return linear movement

        Rich
        Green Bay, WI

        Comment


        • #5
          Linear sprag clutch.
          This is not a detailed drawing nor is it scaled, I am lazy that way. It is just a simple example of the sprag concept. https://en.wikipedia.org/wiki/Sprag_...C%20are%20used.

          I have never seen a linear sprag clutch in the wild but can see no reason that it will not function. It will of course take considerable work to produce, much rough machining then hardening followed by finish grinding.
          Provision must also be made in order to reverse the direction of the work if required, this is what the release pins are for.
          I drew it with 2 sprags for simplicity, once again lazy and not being paid for it (-:, but more may be used depending on load requirements. Each sprag rides in its own, for want of a better term, keyseat.

          Last edited by Bented; 10-09-2020, 05:54 PM.

          Comment


          • #6
            What about the system found on caulking guns? Or grease guns. No "rack" required, though the caulking guns have a rack for moving the shaft, but not for locking it.
            Last edited by Peter S; 10-13-2020, 09:27 PM.

            Comment


            • #7
              Could you use a bendex out of Auto starter and ingage it manually,should be able to find one for free.

              Comment


              • #8
                https://images.search.yahoo.com/yhs/...g&action=click

                Erl field experience here--Google coiled tubing injector. Used to lower/inject tube into deep high pressure wellhead or retrieve. Your application may require thinking outside the box, a BIG box. Hopefully you can use the idea and principle.

                Comment


                • #9
                  Spring Wrapped Clutch.

                  Works in the rotary and linear axis.

                  -Doozer
                  Last edited by Doozer; 10-16-2020, 02:28 PM.
                  DZER

                  Comment


                  • #10
                    Originally posted by Doozer View Post
                    Spring Wrapped Clutch.

                    Works in the rotary and linear axis.

                    -Doozer
                    Yep. Take flat or round spring steel or piano wire and wrap it along the length of a slightly smaller rod. You can experiment with different diameters until the diameter of the formed spring is a moderate press on your target shaft. Your shaft will lock in the direction of the helix and slip in the opposite. I did this using 1/8” wide flat spring to add a lock to the elevation screws of a shooting rest. An internal clutch was needed in my case to allow override of the lock.

                    Comment


                    • #11
                      Micrometers have used wire spring clutches for years as a method of torque control of the spindle, Brown & Sharpe and Mitutoyo for instance. I suspect the load capability of such a device is limited.

                      What is a shooting rest?

                      Comment


                      • #12
                        There seems to be confusion here - the OP mentioned a longitudinal one way clutch, not a rotational type. Or maybe I'm confused too.

                        Comment


                        • #13
                          Originally posted by Peter S View Post
                          There seems to be confusion here - the OP mentioned a longitudinal one way clutch, not a rotational type. Or maybe I'm confused too.
                          Originally posted by Doozer View Post
                          Spring Wrapped Clutch.

                          Works in the rotary and linear axis.

                          -Doozer
                          ...
                          DZER

                          Comment


                          • #14
                            I reverse engineered the mechanism used in the "Quick Grip" clamps and it works well . I first made a wood model and then one out of aluminum. I'll take a pix if any one is interested.
                            ...lew...

                            Comment


                            • #15
                              I have seen close relative to sprag clutch: sping-loaded cylindrical roller(s) in tapered hole
                              Location: Helsinki, Finland, Europe

                              Comment

                              Working...
                              X