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RE: [z_scale] Re: Recommended track gradient

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  • Greg Elmassian
    I want everyone to know that I did not pay Bill to post this! Bill, thanks, I went back and searched and could not find the info, but usually, my memory is
    Message 1 of 20 , Jan 1, 2004
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      I want everyone to know that I did not pay Bill to post this!

      Bill, thanks, I went back and searched and could not find the info, but
      usually, my memory is pretty good (not too many senior moments yet!)

      Bill do you remember if the discussion centered on getting traction by
      getting the drivers on the rails in forward motion, or was it also coupled
      to better electrical contact? (My memory says it was a traction issue, but I
      seem to remember something about crossing the frogs in a switch).

      Regards,

      Greg

      -----Original Message-----
      From: zbendtrack@... [mailto:zbendtrack@...]
      Sent: Thursday, January 01, 2004 5:59 PM
      To: z_scale@yahoogroups.com
      Subject: Re: [z_scale] Re: Recommended track gradient


      Greg:

      > Then it was either a discussion on traction, or related to adding
      > power pickup to the center driver, and the problems with the driver
      > lifting in a certain direction.

      For the longest time there was a folder in the archives that had photos of a

      converted frame...that kept the intermediate drivers on the rails, in both
      forward and reverse directions. I went through all the picture folders in
      the
      archives and apparently the author has removed his pictures.

      Perhaps that person could re-upload those photos? The modification was not a

      tough one to make, and was reversible if you didn't like it.

      And yes, all but the first and last drivers lift up off the rails when
      running in the forward direction. And only the first and last have power
      pickup.

      Bill K.
      Houston


      [Non-text portions of this message have been removed]


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    • zbendtrack@aol.com
      ... The photo s showed tiny brass shims added to the bottom of the slots that the middle axles fit into. The slots are deeper than the diameter of the axles,
      Message 2 of 20 , Jan 1, 2004
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        Greg:

        > Bill do you remember if the discussion centered on getting traction by
        > getting the drivers on the rails in forward motion, or was it also coupled
        > to better electrical contact? (My memory says it was a traction issue, but I
        > seem to remember something about crossing the frogs in a switch).
        >
        The photo's showed tiny brass shims added to the bottom of the slots that the
        middle axles fit into. The slots are deeper than the diameter of the axles,
        which allow the axles to ride up on the idler gears when in forward motion.
        Easy enough to add..no drilling or gluing.

        The purpose was to maintain wheel-to-rail contact for traction. About the
        same time, however, a different author related his success in adding beryllium
        copper power pickups to insides of these same center drivers. Still another
        author added text/photos on tender pickup (my favorite choice).

        I guess the size of the yahoo archives is limited, and even old messages fall
        off the end of the earth in time. Which is a shame, because many questions
        are as perennial as grass.

        Hope this helps,
        Bill K.
        Houston


        [Non-text portions of this message have been removed]
      • jmac_han
        Fellow modellers / modelers, The Z_Scale message archives are intact, nothing has dropped off, yet! You ll notice on the home page that the archives are still
        Message 3 of 20 , Jan 2, 2004
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          Fellow modellers / modelers,

          The Z_Scale message archives are intact, nothing has dropped off,
          yet! You'll notice on the home page that the archives are still
          listed going back to June 1999. No doubt the discussion you speak
          of still exists. Don't forget to search the archives right back to
          the beginning. A first search only looks at the last chunk of 500
          messages or so. Ya gotta keep goin'...

          I don't recall a folder in the photo section on this topic, however,
          if there indeed had been one and it no longer exists then it may
          have been among some older material cleaned out to make room for new
          member photos. I'm not saying that this actually happened, just
          that I and my co-moderators are the only ones, other than the author
          of the folder, who have editing privileges concerning Z_Scale
          content areas.

          Happy Hunting...
          Jeffrey


          --- In z_scale@yahoogroups.com, "Greg Elmassian" <greg@e...> wrote:
          > Well, now the mystery is solved, and you have answered my question
          why I
          > could not be sure if it was traction or pickup...
          >
          > It is a shame about these things dropping off the forum... Maybe I
          should
          > figure out when they fall off, and be sure to archive them. I've
          got room on
          > my web site, and I think I'll start being more aggressive about
          adding them.
        • de Champeaux Dominique
          .. ... The La Mesa Model railroad club (which operates HO scale Tehachapi Pass in San Diego, CA) says, for its maximum grades of 2.2 %, 8 towed axles (ie two
          Message 4 of 20 , Jan 3, 2004
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            ..
            >
            > Does anyone know of any testing that has been done
            > to determine the
            > optimum number of driving wheels for a given weight?
            >
            The "La Mesa Model railroad club" (which operates HO
            scale Tehachapi Pass in San Diego, CA) says, for its
            maximum grades of 2.2 %, 8 towed axles (ie two cars)
            per driving axle. That leads to 8 cars per BB engine,
            and 12 cars per CC engine.
            Cheers,
            Dominique

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          • Scott A. Whitmire
            ... The only determinants of pulling power are the total weight of the loco and the power output it can produce. The number of axles *might* have an effect on
            Message 5 of 20 , Jan 3, 2004
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              At 1/1/2004 08:29 AM, you wrote:
              >--- In z_scale@yahoogroups.com, "Ralph Scott" <ralph.scott@x> wrote:
              > >... Usually the more driving axles a Z loco has the poorer its
              > >pulling ability due to the locos weight being distibuted over more
              > >wheeles. ...
              >
              >A very interesting observation...
              >
              >Does anyone know of any testing that has been done to determine the
              >optimum number of driving wheels for a given weight?
              >
              >If not, this might be a good time to start something. If you are
              >interested, measure the pull power (maximum number of cars, their
              >total weight, track grade etc) and weight of your various locos along
              >with number of wheels and post the results. Maybe we can get some
              >data to add to Ralph's observation.
              >

              The only determinants of pulling power are the total weight of the loco
              and the power output it can produce. The number of axles *might* have
              an effect on the amount of friction (it increases it), but the difference isn't
              enough to matter. I've seen the calculations for tractive effort, and they
              include weight and horsepower, along with some fudge factors for
              wetness and grade.


              Scott Whitmire
            • Glen Chenier
              ... loco ... have ... difference isn t ... and they ... Makes sense, did some web searches on static friction and looks directly proportional to force. Less
              Message 6 of 20 , Jan 3, 2004
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                --- In z_scale@yahoogroups.com, "Scott A. Whitmire" <whitmire@i...>
                wrote:
                > The only determinants of pulling power are the total weight of the
                loco
                > and the power output it can produce. The number of axles *might*
                have
                > an effect on the amount of friction (it increases it), but the
                difference isn't
                > enough to matter. I've seen the calculations for tractive effort,
                and they
                > include weight and horsepower, along with some fudge factors for
                > wetness and grade.

                Makes sense, did some web searches on static friction and looks
                directly proportional to force. Less wheels, more weight on each.
                It would be interesting to measure the weights of different
                locomotives and come up with matching traction comparisons.

                MTL F-7s are 3 ounces and can pull a lot of train or running alone
                can climb 12% grades (experimental test results, not recommended on
                actual layouts).
              • Glen Chenier
                ... Increased locomotive weight increases traction, but does this make it even harder for a locomotive to haul itself up a grade? The original question was
                Message 7 of 20 , Jan 3, 2004
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                  --- In z_scale@yahoogroups.com, "Glen Chenier" <chenierfam@c...>
                  wrote:
                  > It would be interesting to measure the weights of different
                  > locomotives and come up with matching traction comparisons.

                  Increased locomotive weight increases traction, but does this make it
                  even harder for a locomotive to haul itself up a grade? The original
                  question was 'recommended track gradient'.

                  If others would like to take part in a 'tractor pull' locomotive
                  grade climbing comparison, here is a way it could be done by various
                  testers on a standardized test track fixture.

                  Fasten a couple feet of track to a straight board and attach power
                  wires.

                  Dirt can improve traction and give false measurements. Clean the
                  rails and locomotive-under-test (LUT) wheels just b4 testing with a
                  no-residue solvent such as 91% isoproyl rubbing alcohol. Cleaners
                  such as Goo-Gone leave a film on the rails that reduces traction, so
                  avoid these. Let the solvent dry before beginning the test.

                  Prop up one end of the board on any suitable support. Books are
                  useful for this.

                  Run your various LUTs by themselves (no attached cars) up the sloping
                  track. Keep raising the propped-up end on more books to make the
                  grade steeper until the LUT wheels start to slip with trying to lift
                  it's own weight.

                  Measure the rise over run to calculate the grade percentage at JUST
                  BELOW the LUT wheel slippage point.

                  Post your results.
                • Svein-Martin Holt
                  I have not read the whole discussion, but some time ago,(october 2002) I made my own test on my AZL E8 A+B unit, because I was not satisfied with the number of
                  Message 8 of 20 , Jan 4, 2004
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                    I have not read the whole discussion, but some time ago,(october
                    2002) I made my own test on my AZL E8 A+B unit, because I was not
                    satisfied with the number of cars this nice locomotive could handle
                    before it start to spin. The test can be found on this page:

                    http://www.platelayer.com/mj/zanlegg/loadtestAZLE8.asp

                    This engines are heavy, but still they can not pull many cars up a
                    grade. On flat surface(or very low grade) it works very well.
                    This AZL E8 A+B cab take a maximum grade of 5.7% before it start to
                    spin a little, with only their own weight. Other numbers can be
                    found in the link(table).

                    My experience is that the small F7's from both Märklin and MT manage
                    more cars than this E8(Of course, the B-unit is a dummy, and the
                    weight is not much lower than for the heavy A-unit, so much
                    tractionpower goes to move the B-unit). The main reason for that I
                    think, is the number of axels on each boggie. The F7-boggie has 2
                    axels, but the E8 has 3 axels. It looks like the F7 in total has
                    more traction with the 2x2 axels, because they have bigger pressure
                    on the track, compared to the 3 axels boggies for the E8(I have also
                    noticed the same with multiaxles steamers). It may also be a problem
                    that with 3 axels is is more difficult to have all power transferred
                    to the tracks 100%, compared to 2, where you have 4 "corners", with
                    25% of the weight on each wheel, and its more easy to have maximum
                    traction moved to the tracks with that configuration.

                    I will therefor limit the grade on any of my layouts to the smallest
                    possible value, so I will be able to run long trains with my North
                    American equipment. Its not so fun to have only 5 cars behind the E8
                    A+B. Its much better to have all my 30+ coalhoppers in a long drag.
                    I may need to have some tungsten powder in the engine to increase
                    the traction power.

                    My maximum grade will be limited to 2.3%, normally less than that,
                    to have as few problems as possible.

                    In my newest dream(dream, because it is only on the drawing table
                    yet), a small layout featuring Tehachapi Loop, the loop is max 2.5%
                    (2.3% for the outher track), other parts is between 1% and 2%. There
                    may be need for a helper or two, but that will be the same as for
                    the prototype. For this layout the grade in the other direction is
                    less that up the loop, because of longer runs, so the heavy trains
                    will only go down the loop? That may bee a solution. :-)

                    Regards,
                    Svein-Martin Holt
                    www.platelayer.com

                    PS: Follow the building on my new z-scale layout on this link, if
                    you are interested:
                    http://www.platelayer.com/mj/zanlegg/z_layout_e.asp



                    --- In z_scale@yahoogroups.com, "Glen Chenier" <chenierfam@c...>
                    wrote:
                    > --- In z_scale@yahoogroups.com, "Glen Chenier" <chenierfam@c...>
                    > wrote:
                    > > It would be interesting to measure the weights of different
                    > > locomotives and come up with matching traction comparisons.
                    >
                    > Increased locomotive weight increases traction, but does this make
                    it
                    > even harder for a locomotive to haul itself up a grade? The
                    original
                    > question was 'recommended track gradient'.
                    >
                    > If others would like to take part in a 'tractor pull' locomotive
                    > grade climbing comparison, here is a way it could be done by
                    various
                    > testers on a standardized test track fixture.
                    >
                    > Fasten a couple feet of track to a straight board and attach power
                    > wires.
                    >
                    > Dirt can improve traction and give false measurements. Clean the
                    > rails and locomotive-under-test (LUT) wheels just b4 testing with
                    a
                    > no-residue solvent such as 91% isoproyl rubbing alcohol. Cleaners
                    > such as Goo-Gone leave a film on the rails that reduces traction,
                    so
                    > avoid these. Let the solvent dry before beginning the test.
                    >
                    > Prop up one end of the board on any suitable support. Books are
                    > useful for this.
                    >
                    > Run your various LUTs by themselves (no attached cars) up the
                    sloping
                    > track. Keep raising the propped-up end on more books to make the
                    > grade steeper until the LUT wheels start to slip with trying to
                    lift
                    > it's own weight.
                    >
                    > Measure the rise over run to calculate the grade percentage at
                    JUST
                    > BELOW the LUT wheel slippage point.
                    >
                    > Post your results.
                  • Glen Chenier
                    ... smallest ... E8 A+B. Its much better to have all my 30+ coalhoppers in a long drag. This is exactly the kind of information that would be useful to anyone
                    Message 9 of 20 , Jan 4, 2004
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                      --- In z_scale@yahoogroups.com, "Svein-Martin Holt" <post@p...> wrote:
                      > ...I made my own test on my AZL E8 A+B unit, because I was not
                      > satisfied with the number of cars this nice locomotive could handle
                      > before it start to spin. The test can be found on this page:
                      > http://www.platelayer.com/mj/zanlegg/loadtestAZLE8.asp
                      > ...I will therefor limit the grade on any of my layouts to the
                      smallest
                      > possible value, so I will be able to run long trains with my North
                      > American equipment. Its not so fun to have only 5 cars behind the
                      E8 A+B. Its much better to have all my 30+ coalhoppers in a long
                      drag.

                      This is exactly the kind of information that would be useful to
                      anyone buying a new locomotive, or designing a new layout with grades
                      and being able to predict the operating limitations. While 30
                      hoppers are indeed a nice sight and one of the strengths of Z, many
                      do not have the room for even this and must settle for shorter trains
                      and steeper grades if used.

                      In addition to measuring the slip grade limit of various locomotives
                      on their own, the information provided on car-hauling capability on
                      various grades is very helpful too. It is harder to create a
                      standardized test for rolling stock due to the many different types
                      and combinations, but it will give a good guide to all, especially
                      newcomers to Z scale.
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