Loading ...
Sorry, an error occurred while loading the content.
 

Re: Recommended track gradient

Expand Messages
  • Glen Chenier
    ... 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?
    Message 1 of 20 , Jan 1, 2004
      --- 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.
    • Greg Elmassian
      I would say this statement is usually true for Z scale steam locos. I would disagree with it for diesels which have independently gimbaled power trucks and
      Message 2 of 20 , Jan 1, 2004
        I would say this statement is usually true for Z scale steam locos.

        I would disagree with it for diesels which have independently "gimbaled"
        power trucks and shorter wheelbases of the driving axles.

        It's been shown that the middle axle of a 0-6-0 typically lifts and does not
        contact the rail..

        Greg

        -----Original Message-----
        From: Glen Chenier [mailto:chenierfam@...]
        Sent: Thursday, January 01, 2004 8:30 AM
        To: z_scale@yahoogroups.com
        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 data to add to Ralph's observation.
      • MOFWCABOOSE@AOL.COM
        I don t think the middle wheels lift on 0-6-0 or other steam locos so much as they are intentionally made a millimeter or two smaller in diameter so that
        Message 3 of 20 , Jan 1, 2004
          I don't think the middle wheels "lift" on 0-6-0 or other steam locos so much
          as they are intentionally made a millimeter or two smaller in diameter so that
          they do not contact the track. This is so they can get around the 145mm
          curves without derailing.

          John C. La Rue, Jr.


          [Non-text portions of this message have been removed]
        • Greg Elmassian
          I think if you read back a bit, you will find that the 060 drivers were the same diameter, there is more vertical slop in the center driver journal. There was
          Message 4 of 20 , Jan 1, 2004
            I think if you read back a bit, you will find that the 060 drivers were the
            same diameter, there is more vertical slop in the center driver journal.

            There was a discussion about shimming the center driver journal. If I
            remember correctly, the center driver lifted in reverse, and pressed down in
            forward (this may be backwards)... This makes sense since the drive to the
            gear on the driver is pushed in different directions for the different
            motion.

            I think this discussion centered on either loss of electrical contact from
            the lifted driver, or loss of traction.

            I guess someone out there could measure the drivers on an 060 marklin loco
            to confirm this.


            Greg

            P.s. thinking more, I seem to remember someone posted a movie clip that
            showed the center driver moving "up".


            -----Original Message-----
            From: MOFWCABOOSE@... [mailto:MOFWCABOOSE@...]
            Sent: Thursday, January 01, 2004 10:30 AM
            To: z_scale@yahoogroups.com
            Subject: Re: [z_scale] Re: Recommended track gradient


            I don't think the middle wheels "lift" on 0-6-0 or other steam locos so much

            as they are intentionally made a millimeter or two smaller in diameter so
            that
            they do not contact the track. This is so they can get around the 145mm
            curves without derailing.

            John C. La Rue, Jr.
          • zbendtrack@aol.com
            ... 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
            Message 5 of 20 , Jan 1, 2004
              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]
            • 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 6 of 20 , Jan 1, 2004
                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!




                ------------------------------------------------------------------------------
                Yahoo! Groups Links

                a.. To visit your group on the web, go to:
                http://groups.yahoo.com/group/z_scale/

                b.. To unsubscribe from this group, send an email to:
                z_scale-unsubscribe@yahoogroups.com

                c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



                [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 7 of 20 , Jan 1, 2004
                  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

                  To visit your group on the web, go to:
                  http://groups.yahoo.com/group/z_scale/

                  To unsubscribe from this group, send an email to:
                  z_scale-unsubscribe@yahoogroups.com

                  Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
                • 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 8 of 20 , Jan 1, 2004
                    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 9 of 20 , Jan 2, 2004
                      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 10 of 20 , Jan 3, 2004
                        ..
                        >
                        > 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 11 of 20 , Jan 3, 2004
                          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 12 of 20 , Jan 3, 2004
                            --- 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 13 of 20 , Jan 3, 2004
                              --- 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 14 of 20 , Jan 4, 2004
                                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 15 of 20 , Jan 4, 2004
                                  --- 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.
                                Your message has been successfully submitted and would be delivered to recipients shortly.