Announcement

Collapse
No announcement yet.

Clutch---again

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

  • Clutch---again

    Earlier this winter I designed and built a clutch, to use between one of my i.c. engines and a model sawmill I designed and built. Unfortunately, although the clutch worked, it had issues with internal binding which robbed a lot of the power, to the extent that my small engines couldn't cope with it. The design you see posted here is the design that I built and had the problems with. I am going for a total redesign, which although it will still be a cone type clutch with a wooden cone, the actuator will be a purchased Destaco type "push-pull" clamp.
    Last edited by brian Rupnow; 04-02-2013, 06:17 PM.
    Brian Rupnow

  • #2
    The first clutch I made was made with what I had laying around. This time, I'm getting more serious. I'm actually spending some money. I have bought a Destaco style "push/pull" clamp, and 6 bearings (I may not use them all) from Canadian Bearings, a local supplier. The bearings are single row sealed ball bearings, 1/2" bore x 1 3/8" o.d. x 7/16" wide. Before anyone jumps on my back about using "thrust bearings", keep in mind that the engines this will be used with are micro horsepower. A normal ball bearing is well capable of withstanding any axial thrust loads they will see in the applications I have planned for them. The shaft will be supported at one end only, and the entire design will be more amenable to changing belts on than the previous design. I am still early in the planning stages of this clutch, as you will see by the sketches on the paper under the bearings. I don't recomend that anybody jump right in and start building this with me. I want to finish this one and "field try" it to avoid some glitch showing up "after the fact". I will post pictures and models as this develops, and a video of the field trial" when it is finished. I will also try and address any shortcomings that the previous design had, one of the big issues on the first clutch being the limited size and type of pulley used on it.----Brian
    Brian Rupnow

    Comment


    • #3
      I enjoy the eye-popping computer design work you share with us and the old pencil-and-paper sketches here look great as well. Your success should be rewarded with all the planning and thought beforehand. Thanks again for sharing.
      Cheers,
      Gary

      Comment


      • #4
        This is uglier than original sin, but its a start. The pulleys are not shown yet. Neither is the die spring that forces the cone away from the receiver. However, I've been working 3 hours on it and thats enough for tonight.
        Brian Rupnow

        Comment


        • #5
          Brian, THIS time make your wooden cone from END-GRAIN wood. That will ensure uniform friction properties. It may not matter, but they are, in your words, micro-horsepower, and you may as well minimize all the variables possible.
          Duffy, Gatineau, Quebec

          Comment


          • #6
            Brian I know we're talking micro HP here but had you considered shielded bearings instead of sealed, there's a lot more torque required with sealed.

            Comment


            • #7
              If I understand your proposed design, you are applying an external force to keep the clutch in engagement. This would result in an increase in bearing friction , in addition to the load being driven.

              With micro power available, would it not be better to have the engagement force contained within the clutch, as it is in an automobile clutch, for example? An external force would only be applied for disengagement.

              Comment


              • #8
                Thank you all for looking and the advice given. I asked for unshielded bearings, but sealed was all they had at my brg supplier. I know they have more frictional drag, but I am running i.c. engines, not Stirlings. I don't like that big long Destaco style clamp, after seeing it in the asssembly. It delivers the linear action I want, but its just too huge. I will attempt to design a simple cam action today to replace it---after all, I only need 1/16" linear movement to engage/disengage the clutch. I have to actually put all my ideas down in a drawing to see if they look realistic or ridiculous. ---More to come.
                Last edited by brian Rupnow; 04-03-2013, 12:10 PM.
                Brian Rupnow

                Comment


                • #9
                  Great postings Brian, very interesting and enjoyable to follow this project !

                  Comment


                  • #10
                    Originally posted by brian Rupnow View Post
                    Thank you all for looking and the advice given. I asked for unshielded bearings, but shielded was all they had at my brg supplier.
                    rbi-1621-2rs are listed as sealed bearings not shielded. As pointed out earlier, shielded would reduce drag. Ed P

                    Comment


                    • #11
                      It's easy to pop the shields or seals out of a bearing.

                      Comment


                      • #12
                        And as pointed out earlier, these bearings are what I was able to get. I like this design better. The Destaco clamp is gone. The base is much shorter. The clamp has been replaced by a cam type lever to engage the clutch, and a die spring mounted internally disengages the clutch. There is enough room to put a 6 1/2" outer diameter pulley on either hub. The belts can be assembled without taking anything apart. There are fewer bearings. the blue center shaft does not rotate. It is a stationary, cantilevered design. All axial forces are transmitted through the bearing balls.

                        Last edited by brian Rupnow; 04-03-2013, 12:16 PM.
                        Brian Rupnow

                        Comment


                        • #13
                          why not use a simple centrifugal clutch?

                          Comment


                          • #14
                            I know it's a model and not doing heavy work, but could there be an overhang issue? It doesn't need support on both sides of the assembly?

                            Comment


                            • #15
                              A centrifugal clutch won't work, as these are low speed and basically constant speed engines. The overhang issue---I'm not certain. There is only 3 1/4" of overhang. I weigh 250 pounds and I could stand on the end of that 1/2" cold rolled steel rod without any signifigant deflection. I don't think my fractional hp engines are going to have too much effect on it. One of the reasons for the cantilever design is to make it easy to change belts without taking things apart. However, this is a prototype. If the rod did deflect, all of the other parts are still valid, even if the design had to change a bit.
                              Brian Rupnow

                              Comment

                              Working...
                              X