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  • easy differential design

    I was musing over a Berkeley sports car I used to own with a clever differential. It was powered by a 328 CC motorcycle engine . The differential was a drum that had a roller chain sprocket on it. Inside were 2 straight-cut axle-half gears connected by 2 pairs of small long gears on opposing sides of the drum. They were meshed with each other and one meshed with one axle-half gear and the other with the other side axle-half gear. The halves were spindled in bearing blocks.

  • #2
    Gonna need some sort of illustration on that one.

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    • #3
      spur gear diff
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

      Comment


      • #4
        from: http://ycraf.blogspot.ca/2010/06/dif...al-render.html


        I was looking at it to see about doing something for an electric ride-on truck for my kid. There are a few designs floating about, though I think the output axles will need a lot of support. I do like the design as there's no gear movement when going straight. The gears only roll when there's an... um... differential I was toying with throwing the entire thing in a PVC pipe with a belt grove at one end instead of a sprocket.


        If there's something simpler, I'd like to know about it.

        David...

        edit... you know, making 4 of those end-mounts with some space in-between would give 2 bearings per axle. The thing could be in a tube the whole length between the frame with the axles then going through a couple of standard pillow blocks then to the wheels. That would be rigid enough to resist the side-load from the sprocket/pulley.
        Last edited by fixerdave; 06-01-2014, 01:08 AM. Reason: still thinking
        http://fixerdave.blogspot.com/

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        • #5
          The most simple diff I have ever seen was in my RC cars. Specifically an Associated RC10 GT. It was the main drive gear in the center was drilled with several radial holes. The holes held ball bearings. That assembly was sandwiched between to plates. The plates had the drive yokes for the axles on them. Everything was held together by a bolt through the center. I don't know if this design will scale up well, but it is dirt simple and could be made in a home shop easily.


          Last edited by Boostinjdm; 06-01-2014, 02:08 AM.

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          • #6
            Hey Boostinjdm

            Thats cool and simple .. but

            How does that thing work. Can't see how that allows one wheel to turn at a diff rate than
            the other.

            Mike A
            John Titor, when are you.

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            • #7
              Originally posted by mikeamick View Post
              ...
              Can't see how that allows one wheel to turn at a diff rate than
              the other.

              Mike A
              The ball-bearings can rotate in the gear that drives them. Thus, as they also friction-drive the plates that drive the axles, one plate can turn faster while the other slower. I suppose avoiding friction between the gear and balls, while maintaining friction between the balls and plates might be an issue. Then again, like the spur gear diff, nothing really needs to slip when going straight. In scaling up, I think the main problem would be maintaining the force to keep the balls driving the friction plates. Probably need a lot of it.

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

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              • #8
                Originally posted by Boostinjdm View Post
                The most simple diff I have ever seen was in my RC cars. Specifically an Associated RC10 GT. It was the main drive gear in the center was drilled with several radial holes. The holes held ball bearings. That assembly was sandwiched between to plates. The plates had the drive yokes for the axles on them. Everything was held together by a bolt through the center. I don't know if this design will scale up well, but it is dirt simple and could be made in a home shop easily.


                Take this design and mount two sets of ball bearings. Have holes in the axle flange as well. Spring load the axle flange on each side to apply pressure to the center. Play with the spring pressure with an adjustment nut to apply more or less pressure. This is how some drill clutches work.
                Location: The Black Forest in Germany

                How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                • #9
                  Incidently I am right now involved in the renovation of a Kerrison WWII anti aircraft gun predictor which is a big heavy box of gears and umgubbins intended to assist the aim of the gunners.


                  This is an American made version but quite like the original.

                  There are two analogue computers, of sort, in the box based on ball and disk integrators and magical little assemblies which include a stage or two of those spur gear differentials.

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                  • #10
                    The current Dodge (Ram) Power Wagon uses a spur gear differential.
                    Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                    ~Practitioner of the Electromechanical Arts~

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                    • #11
                      The Austin 7 used a spur gear diff, and most of the full time 4wd transfercases do too, including the NP-242 used in jeeps/hummer, etc.

                      allan

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                      • #12
                        Here are a few examples http://www.stirlingsouth.com/richard...ng_penguin.htm
                        Helder Ferreira
                        Setubal, Portugal

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                        • #13
                          Originally posted by trackfodder View Post
                          I was musing over a Berkeley sports car I used to own with a clever differential. It was powered by a 328 CC motorcycle engine .
                          I used to have one with the Royal Enfield 70cc Constellation engine in it.

                          Not though about if for quite some while, mine you it was a bit of a nail, more fibre glass repair than car.
                          .

                          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                          • #14
                            Another type:

                            http://www.freepatentsonline.com/6722484.pdf
                            figure 4a of the pdf shows the principle operation.

                            Kind of a 'Detroit locker' action. It doesn't divide the power, just makes sure one can overrun without scrubbing, or if the faster wheel loses traction the axle will speed up to drive the inner wheel as long as the outer wheel is has no traction. This is a bidirectional version of the starter drive I first saw in Japanese motorcycles years ago.

                            paul
                            paul
                            ARS W9PCS

                            Esto Vigilans

                            Remember, just because you can doesn't mean you should...
                            but you may have to

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                            • #15
                              Originally posted by John Stevenson View Post
                              I used to have one with the Royal Enfield 70cc Constellation engine in it.

                              Not though about if for quite some while, mine you it was a bit of a nail, more fibre glass repair than car.
                              SJ I think you missed a zero, or at least I hope you missed a zero or you would have been going nowhere very very fast....


                              Bare in mind it's also British CC's so that would put you at about as much HP production as "normal peoples" 45cc engines of the time...

                              Edit; ( Clumsy Bastard... )
                              Last edited by A.K. Boomer; 06-01-2014, 10:20 AM.

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