Announcement

Collapse
No announcement yet.

variable speed "V" belt

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

  • variable speed "V" belt

    HI All
    I am looking for an article posted in The Home Shop Machinist or Machinist Workshop that I lost.
    This article is about a variable speed ā€œVā€ belt drive system used on a drill press or small mill. This is a simple setup using a double pulley mounted on a jackshaft with a handle for movement. I believe the top and bottom parts are fixed and the center part moves up and down. This happens when the handle is moved and the belt pressure moves the center part up or down and changes the ratio of the pulleys and the speed of the output shaft. I saw one on a drill press many years ago and wish to build on now.
    Any help would be welcomed.
    Thanks
    Tom

  • #2
    My lathe uses this system. I am going to do a similar thing for my mill, using a moped variator, when I find the suitable parts.
    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


    • #3
      Look at a lawnmower

      Riding lawnmowers use something like this. Started back with John Deere and Bolens back in the '70s. Can't be too complex.

      Comment


      • #4
        If you add a differential to the variable speed pulley and you can go from a 1:1 ratio forward to a 1:1 ratio in reverse without having to shift gears.

        Comment


        • #5
          variable speed

          Hi
          Thanks for the reply, how ever the drawing shown here is not what I was looking for.
          I cannot attach my drawings to show the lay out of what I am describing. Peter your lathe may have what I am looking for could you send a drawing??? The Moped type pulley is driven by speed with a centrifugal system and will not work as a variable speed changer. What I am looking for will either increase of decrease the speed between the input and output by moving the handle.
          maybe they will grant me the option to manage files and I can send the drawings.

          Have fun

          Tom

          Comment


          • #6
            Hi Tom.

            Here is a pic and the factory drawing of my lathe setup. The pic is from when I first bought the machine and needed to source a belt. I do understand that the scooter variator pulleys are centrifugally operated - I was thinking I could cobble a manual control over one and do-away with the rollers.

            Click the small drawing for the full-sized version.

            Pete.



            Last edited by Peter.; 07-13-2009, 03:21 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

            Comment


            • #7
              Tom,

              I know exactly the type drive you want to build, I have two machines that use it.

              A few points about these type drives..

              They aren't the easiest thing to make so it works smoothly without sticking.

              They aren't very efficient. V-belt drives generally aren't, but these are worse.

              The adjusting lever won't stay in position without locking it down.

              Speed control is not really good.

              Most of these drives need special, wider v-belts to operate. The belts are stiff and relatively expensive.

              Unless you have some reason to want this type drive specifically I suggest a VFD. The machines I have using this drive were expensive in their day and used it because there were no other viable options. Later versions of the machines use electronic speed control.

              Comment


              • #8
                Variable speed vee belt drives are as common as combines, CVT quads (like my Can Am), and snow machines (like my family's old Skidoo). Combines use them with a control arm to vary the ground speed (like the lathe configuration shown, but usually hydraulically activated). The pulleys have one side that slides in and out on a spline. The drive pulley is controlled by a control arm and a bearing similar to a throw out bearing on a clutch pressure plate (like on a combine) or a set of weights and links that force the sides of the drive pulley together - faster engine speed forces the pulley closed (like on a snow machine). The driven pulley is held closed by a spring which allows the pulley sides to opens up as the drive pulley closes. The range of variable ratio is roughly from 4:1 reduction to about 1:2 overdrive.

                A drive belt for a combine might be as big as 3" across the spine while snow machine belts are 2" or less.
                Last edited by camdigger; 07-13-2009, 08:22 PM.
                Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

                Comment


                • #9
                  MTD mowers used them,IIRC the aftermarket replacements cost $70.

                  Lovejoy makes preety much anything you would ever want,plus they're online catalog has actual dimensions on the parts-

                  http://www.lovejoy-inc.com/uploadedF...talogs/vsd.pdf
                  I just need one more tool,just one!

                  Comment


                  • #10
                    variable speed

                    HI
                    Thanks for replys I found one on Ebay and bought it.
                    Great to be able to throw out a question and have many answer it.
                    I still would like to see the build it yourself article from home shop.
                    have fun
                    Tom

                    Comment


                    • #11
                      I vaguely remember that HSM article, but I thought it was just an outboard jackshaft that was manually changed? I didn't think it was a Reeves drive?

                      Originally posted by DR
                      Most of these drives need special, wider v-belts to operate. The belts are stiff and relatively expensive.
                      The Vari-speed belts on my Clausing 5914 are about 4 times as wide as a conventional V-belt, and yes, they're very expensive You can probably go cheaper if you find a snowmobile belt. At least, I'd assume that snowmobile belts are cheaper than machinery-branded belts.

                      Unless you have some reason to want this type drive specifically I suggest a VFD. The machines I have using this drive were expensive in their day and used it because there were no other viable options. Later versions of the machines use electronic speed control.
                      Good advice. Most of us that have VariSpeed machine tools (Bridgeport Varispeeds, Clausing VariSpeed, etc.) wish we didn't
                      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                      Comment


                      • #12
                        variator test

                        HI
                        This is a test
                        If it were the real thing you would be dirrected to say hello.

                        Comment


                        • #13
                          variator

                          HI George
                          Thanks it works
                          That is a picture I was sent of what I am looking to build. And if I ever get the article I will.

                          Have fun
                          Tom

                          Now to order the other back issues for another projuect.

                          Comment


                          • #14
                            I can see how the ratios will change with various postions of the double sheave, but how does the whole set up account for the change in center distances for the different ratios?
                            Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

                            Comment


                            • #15
                              The belts slide up and down the sidewalls of the Vari-speed sheave as the center distance changes.

                              That's the primary loss of efficiency, and why they get so hot...
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                              Comment

                              Working...
                              X