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Re: [z_scale] Re: Recommended track gradient

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  • Ralph Scott
    I worked out that 7 sections of 8530 track layed in a circular configuration and one end raise just high enough to clear a 8911 catenary mast works out at a
    Message 1 of 20 , Jan 1, 2004
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      I worked out that 7 sections of 8530 track layed in a circular configuration and one end raise just high enough to clear a 8911 catenary mast works out at a bit over 4.8% gradient (42mm in 850 mm). A class 111 with 3 silver fish coaches will struggle to get up this gradient. Change the 111 for a 120 and this is no problem at all. Substitute again with a 141 (CoCo trucks) and this no go as was the crocodile. Try this with 0-6-0 diesel shunter and it is also not a problem. I tried this with class 50 steam loco. It made it up the slope with 2 silver fish carriages.
      Ralph
      ----- Original Message -----
      From: Glen Chenier
      To: z_scale@yahoogroups.com
      Sent: Friday, January 02, 2004 5:24 AM
      Subject: [z_scale] Re: Recommended track gradient


      --- 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
      good data to help answer Ralph's question.



      "Z" WARNING! HANDLE WITH CARE! Highly addictive in Small DoseZ!




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      [Non-text portions of this message have been removed]
    • 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 2 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]


        "Z" WARNING! HANDLE WITH CARE! Highly addictive in Small DoseZ!


        Yahoo! Groups Links

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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 3 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 4 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 5 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

              _________________________________________________________________
              Do You Yahoo!? -- Une adresse @... gratuite et en français !
              Yahoo! Mail : http://fr.mail.yahoo.com
            • 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 6 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 7 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 8 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 9 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 10 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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