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Side Rod offset

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  • Nelson Snedeker
    Hi Guys: Having built several Steam Engines , one of which is a live O gauge , I think a bit of steam info. might be helpful to understand why the side rods
    Message 1 of 2 , Apr 3, 2003
      Hi Guys:

      Having built several Steam Engines , one of which is a live "O" gauge ,
      I think a bit of steam info. might be helpful to understand why the side
      rods are in different positions on each side of the Loco . The cylinders
      on each side are individual Double action ( push/pull ) engines , and
      are subject to being stopped with side rods on dead center and will not
      start again until moved off dead center . The solution to this problem
      on two cylinder ( two engine ) Loco's is to have their centers exactly
      90 degrees apart on the axle that connects them together . This makes it
      impossible for both engines to be stopped on dead center and one side or
      the other will always be in position to start the Loco . Any multiple
      cylinder Steam Engine therefore does not need or require a flywheel and
      should explain why a Loco can start into motion when the wheels ( in
      effect the so-called fly wheels ) are not previously spinning . The
      weights on the wheels are counterbalances to the weight of the side rods
      and valve rods and any other attachments to that particular wheel . In
      the case of our little jewels , the side rods do not drive but , are
      driven by a gear train and because of the tolerances required , a
      perfect 90 degree orientation is impossible . Marklin has solved the
      problem by slotting the end holes in the side rods and any "thumping"
      you get is because you are off one gear tooth on one end or the other
      and the pins are hitting the end of the slot before they go over center
      . I hope I didn't make this too technical but live steam info is dying
      out along with us dinosaurs who lived with it . I may add that my 88641
      was a mild "thumper" right out of the box and one gear tooth correction
      made it a totally quiet performer .

      Happy "Z"ing Nel
    • jmac_han
      Hi Nel, Terrific explanation. Your observation that the steamer was 1 gear tooth out of synch right out of the box doesn t surprise me one bit. While touring
      Message 2 of 2 , Apr 3, 2003
        Hi Nel,

        Terrific explanation. Your observation that the steamer was 1 gear
        tooth out of synch right out of the box doesn't surprise me one bit.
        While touring the Märklin factory last year I was amazed to see the
        so-called test run area. The locos were placed on a test track and
        run at FULL speed around the track, first forward then
        backward...then placed in the box for shipment! No wonder the
        thumpers manage to get through their QA. Too bad since I've had
        nothing but trouble with Märklin steamers and had to fine tune them
        myself. This is no way to build confidence in a product.

        It almost makes one wonder what Märklin really thinks about their Z
        line. Collectors don't need good running locos, do they?

        Cheers,
        Jeffrey
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