[python] Re: pivot quality

[python] Re: pivot qualityChecked out both sites and yes the auto bearings look 
like they would work much better and as an added bonus they can be bolted on 
instead of welded.I was thinking maybe ask a aircraft company about stresses 
for those rods,they are control rods for alerons,as you have them installed on 
your pyton allready you may as well test them for a few hundred miles and check 
the results.
  ----- Original Message ----- 
  From: Thomas P Jahn 
  To: python@xxxxxxxxxxxxx 
  Sent: Wednesday, April 11, 2007 12:54 AM
  Subject: [python] Re: pivot quality


  Hey August,


  you name it. I was thinking of such a pivot using "aircraft rods". I just 
didn't know, how they are called. :-)
  The idea was to use two of them in order to have an adjustable pivot angle 
without changing other aspects of the geometry. The lower bearing could be 
fixed and the upper one should be movable forth and back.


  
www.aurorabearing.com/products/aerospace-military/aerospace-series/rod-ends/male/default.html


  I am a little in doubt though that 2 "aircraft rods" will give sufficient 
strength/support. Therefore, I was thinking of using a ball bearing from a cars 
front wheel suspension as the lower bearing. Those bearings are very stable and 
carry 300 kg when the car is just standing still. The dynamic forces must be 
much higher.


  
http://www.yatego.com/atv-schiffke/p,44c9c353c6afa,434630b1776d88_0,vw-traggelenk-vw


  I think that should work.


  cheers
  Thomas










    I was looking over various pivot designs on all the Phyton bikes and was 
wondering about the aircraft type rods they look pretty simple to consruct 
but.is there any info on how they work and hold up I relize aircraft spec parts 
are extremly strong but they were never inteaded to be use as pivot bearings 
under so much weight is that a proplem?

      ----- Original Message -----
      From: Torben Scheel
      To: python@xxxxxxxxxxxxx
      Sent: Tuesday, April 10, 2007 11:42 PM
      Subject: [python] Re: pivot quality


      Hi Dirk!

      It is ball bearings, right? Roller bearings is a lot better for the 
purpose, but the stress on the pivot _is_ extreme. I have not ridden my Python 
enought to say if the Flevopivot is better, but I'd expect it, even if it isn't 
designed for the tilting force.
       
      As for the rust - you'll notice that a lot of the danish bikes is coated 
with a layer of a chemical (usually pigmentated) called "paint". It helps in 
some extent - the powder version is the toughest, but it kind'a limits your 
tinkering, when it's applied :-)

      Cheers,
      Torben

        -----Original Message-----
        From: dirk.bonne@xxxxxxx
        To: python@xxxxxxxxxxxxx
        Date: Tue, 10 Apr 2007 21:54:53 +0200
        Subject: [python] Re: pivot quality

        Hi Jürgen,

        To make a good photo of such a little thing is easier asked then done.
        It rises far above my abilities with the camera to make a photo of the
        small dents in the bearing cap. I attached my best result ---still
        better then some of the UFO photos but not a lot. With a little bit of
        good will on your side, you can see the dents at regular distances on
        the inner cap. I can easily feel the dents by going over the cap wall
        with my finger nail. The dents are nearly all around with some places
        are worse (I suspect the front or back). All the caps have dents.

        Now for the reason, I do not want to give the full fault to the
        bearings. I have mistreated them by heating them up (I did not braze on
        the shell directly, but I remember welding my handlebar tube on the
        frame while having the bearings in and that may have been near enough).

        Anyway I do not think this pivot solution is so neat: These bearings are
        not sealed, and even though I filled the pivot up with grease, there was
        still a lot of sand in it (I attached a photo of the pivot shell where
        you see the flimsy sealing solution I choose: just a spacer above and
        below). You can also see the rust: Denmark has not only a lot of sand it
        is also very salty...

        liebe Grüße,
        Dirk

        Jürgen Mages wrote:
        > Hej Dirk,
        >
        > did you use these bearings:
        >
        > http://dirkb.dnsalias.net/image/python/skf_7201B.half.jpg
        >
        > As far as I remember, Eduardo from Brazil used the same
        > type of angular contact ball bearings (Schrägkugellager).
        >
        > If so, these pivot types are left for the choice:
        >
        >  - tapered roller bearings
        >  - rod end bearings
        >  - cartridge bottom bracket
        >
        > Could you please send us a photo of the destroyed bearings?
        >
        > Groetjes,
        > Jürgen.

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