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Re: [HOn3] dcc and older engines

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  • John Stutz
    Regarding DCC and older engines, it seems to be generally assumed that the control dropouts associated with these engines are caused by momentary shorts that
    Message 1 of 11 , Feb 2, 2007
      Regarding DCC and older engines, it seems to be generally assumed that
      the control dropouts associated with these engines are caused by
      momentary shorts that are difficult to reproduce. I have no personal
      experience with DCC debugging, but I wonder if this loss of control
      might also be caused by momentary open circuits? Almost all brass
      engines are "sprung" in a manner that ensures that the whole weight of
      the engine is carried on only 3 driving wheels. If only one driver on
      the hot side is bearing, then anything that interrupts it's contact will
      open the DCC circuit. Such open circuits will be exceedingly difficult
      to isolate, since they are often due to momentary track conditions, that
      can be disturbed by any motion of the locomotive.

      Another problem area in both DC and DCC is the conventional power
      routing drawbar, which often has poor contact. This may be a point
      where the MDC insulated drawbar is an operational advantage over most
      brass engines, since it requires a solid wire conductor.

      Both problem areas are addressed by adding tire wipers to the drivers,
      directly wired to the motor or controller circuit. Tender wheel wipers
      also help, but locomotive drivers are at least partially self cleaning,
      while tender wheels just accumulate insulating crud. I suggest driver
      tire wipers over track sliders, because while wipers absorb motor power,
      the do not decrease tractive effort, while track sliders must be very
      carefully adjusted to keep from seriously decreasing a locomotive's
      pulling ability.

      John Stutz
    • Brett Payne
      Mark, I am talking about it handling and not creating current. We had a doozy here on Wednesday evening when all the locos on a members HO layout ran like jack
      Message 2 of 11 , Feb 2, 2007
        Mark,
        I am talking about it handling and not creating current.

        We had a doozy here on Wednesday evening when all the locos on a members
        HO layout ran like jack rabbits. After about an hour we thought to
        check the track voltage but only after noticing really hot lamps and
        dropping resisters when we had the lid off one model.

        The Booster voltage had crept up to 19 volts! And the circuit to set
        the voltage in the booster was no longer working.

        Brett



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      • Bill Nelson
        one way to check for shorts or bad connections in an older brass locomotive is to run it in the dark and look for sparks I made great
        Message 3 of 11 , Feb 3, 2007
          one way to check for shorts or bad connections in
          an older brass locomotive is to run it in the dark and
          look for sparks I made great improvements on my ornery HO
          Gem Little River 2-4-4-2 only after running it in a slightly
          darkened room. I then ran it on a test track directly in
          front of me in a pitch black room. After hard wiring
          the tender to the locomotive, butting wipers on the tender
          truck axles, and running the power from the wipers to the
          wire between the locomotive and the tender; and adding
          wipers on the locomotive drivers (insulated and non
          insulated), and get them hooked up to the motor's terminals.
          Basically I try to get the electrons in a wire as close
          to the rail as I can and keep it there. This strategy
          has helped drastically improve the performance of many of my
          older brass engines (all my brass is old, come to think of
          it). Once a brass engine reaches a certain age, I can no
          longer count on the original electrical path to work worth
          beans. I can't produce the science to back it up, but I
          firmly believe old brass doesn't conduct electricity well.



          I am just beginning to play with DCC @ my local
          club, where the standard gauge is all Dcc. I have
          purchased a Proto 2000 0-6-0 with sound and DCC, and I am
          working on converting a Westside Sierra RR # 18 2-8-0 to
          DCC to see how it does. DCC is not an option on my home
          RR, where the grades are too steep, and all the space in
          my locomotives is taken up with lead.


          The possibilities with DCC, are awesome, but the
          learning curve can be steep. I think that DCC can almost
          be another hobby in itself.


          Bill Nelson
        • Paul Richardson
          Bill, I think the biggest problem with old brass and conductivity is a surface which looks clean but electrically it is dirty. One of the biggest offenders is
          Message 4 of 11 , Feb 4, 2007
            Bill,



            I think the biggest problem with old brass and conductivity is a surface
            which looks clean but electrically it is dirty. One of the biggest offenders
            is the tender bolster and the contact surface on the truck where it rubs
            against the bolster. Wipers and even a wire that attaches to the tender
            floor and the top of the truck can help improve loco performance. Wipers on
            the drivers will also help performance. The wiper on the insulated side must
            remain insulated from the loco shell and frame so be sure attach the wiper
            with an insulating surface between the shell/frame and the wiper and attach
            with a small nylon screw. Solder a wire from the wiper and attach to the
            motor contact.



            You made a valid point, running the locos in a darkened room will help
            locate the momentary short that sometimes occurs. Once you have located the
            short you can take the steps necessary to insulate the point where a
            momentary contact is made (sometimes a "paint job" of clear nail polish will
            be enough to stop the short). Discretion being the better part of valor do
            not use your wife/girlfriend's nail polish to do this. If you do, you will
            have more serious problems than a temporary short!



            Best regards,



            Paul Richardson



            [Non-text portions of this message have been removed]
          • John R. Short
            John, As always, I find your postings to be very useful, and of maximum benefit. I now have a question for you related to your comments regarding the
            Message 5 of 11 , Feb 4, 2007
              John,

              As always, I find your postings to be very useful, and of maximum benefit. I now have a question for you related to your comments regarding the springing of the locomotive causing it to rest on 3 drivers:

              I have two HOn3 brass locos, Sunset and PFM, that caused me no end of grief with what appeared to be intermittent contact. I tried everything, and was about to relegate these locomotives to scenery status, when I got the notion to respring with NWSL Wimply springs. The problem was solved! Does this agree with your findings as well? Should all drivers receive Wimpy springs, or should at least one set be stronger? Thanks in advance for your reply.

              John Short
              Durango in HOn3, ca. 1948

              [Non-text portions of this message have been removed]
            • John Stutz
              ... John This is just the sort of thing I was talking about. Most sprung brass engines, particularly the older ones, were sprung so strongly that they were
              Message 6 of 11 , Feb 4, 2007
                > From: "John R. Short" <johnsk28@...>
                > John,
                >
                > As always, I find your postings to be very useful, and of maximum
                > benefit. I now have a question for you related to your comments
                > regarding the springing of the locomotive causing it to rest on 3
                > drivers:
                >
                > I have two HOn3 brass locos, Sunset and PFM, that caused me no end of
                > grief with what appeared to be intermittent contact. I tried
                > everything, and was about to relegate these locomotives to scenery
                > status, when I got the notion to respring with NWSL Wimply springs.
                > The problem was solved! Does this agree with your findings as well?
                > Should all drivers receive Wimpy springs, or should at least one set
                > be stronger? Thanks in advance for your reply.

                John

                This is just the sort of thing I was talking about. Most sprung brass
                engines, particularly the older ones, were sprung so strongly that they
                were essentially rigid. And since those springs were pushing the axle
                bearings down against a thin cover plate, the drivers were rarely in the
                same plane. As an extreme example, I had a Balboa C-21 that was sprung
                so hard that the builder had bent the frame and cover plate to opposite
                arcs, in order to keep the driver springs from visibly pushing them
                apart! A close look at any of the Hallmark EBT Mikes will show that
                the side rods are not jointed. Clearly Hallmark did not expect the
                drivers to be moving in the frame slots.

                Your solution largely fixes this problem, by getting the springing just
                soft enough that most of drivers are down on the rail most of the time.
                But I think that you were lucky on the weighting. I suspect that a real
                close look at your engines will show that most of the bearing are still
                against the cover plate at the bottom of their slots. Which is not a
                necessarily bad, if they are only just touching the cover plate.

                The potential problem is that if a sprung locomotive normally sits with
                all axle boxes at mid-slot, then the draft forces on the drawbar or
                coupler can cause the body to pitch backward or forward. Pitching back
                usually just looks awkward. Pitching forward can put the pilot on the
                railhead, giving a momentary short. You may see a little of this in
                your engines if you look closely, but clearly it is not a major problem
                for you.

                If the springs are just soft enough that the locomotive weight just
                barely lifts the bearings off of the bottom of their slots, then any
                driver can rise over a high spot without lifting the others on that side
                off of the rail. So you always have some weight on all drivers, and
                good electrical contact despite slight track irregularities. But when
                the locomotive starts to pitch forward, the rear drivers do bottom, and
                start to lift off of the rail. This shifts the center of support well
                forward, just ahead of the second driving axle on a mike, and so the
                locomotive does not pitch any further forward. Just the opposite
                happens when pulling.

                Much the same can be achieved with very weak springs, so that the driver
                bearings are near the top of their slots. Here, as the locomotive
                pitches forward or aft, the leading or trailing driver bearing hits the
                top of its slot and immediately sees a much larger load, which stops the
                pitching. This approach will put most model locomotives closer to the
                rails than usual, with increased potential for shorts to side and main
                rods, and around the trucks. Partial top filling of leading and
                trailing driver bearing slots may be used to get the locomotive back up
                above the rails. In which case springing should stiffer, to keep these
                two axles just free of the new stops.

                It just occurred to me that leading and trailing axle slot top fillers
                will also largely stop pitching of a locomotive sprung with soft mid
                slot springs. I am going to have to try this one. It will almost
                certainly give the best rough track performance, since it allows maximal
                movement of the inner driver axles.

                A possible third approach is to make the leading or trailing driver axle
                rigid in the frames, with mid-slot springing on the others. Then any
                pitching action pivots around the rigid axle, and is resisted by all of
                the driver springs, while all drivers are still able to follow track
                irregularities. However on rough track, the locomotive body will follow
                the motion of the rigid axle, which may be undesirable. The previous
                methods tend to even out such tracking irregularities. I do not know if
                anyone has ever tried this one.

                Any operating (non-rigid) springing requires that the locomotive weight
                be well centered over the driver wheelbase, and that the weight be
                carefully matched to the springs. Or match the springs to the weight.
                The NWSL "wimpy" springs are probably about right for HOn3 Mikes
                operating in the bottom of axle slots mode, with some weight adjustment.
                Kadee's wide range of coupler springs offer possibilities for lighter
                locomotives, or for heavy locomotives operating in the top of slots mode.
                Coil springs can be streached to increase their preload, and cut shorter
                to make them stiffer, but there is not much you can do to make them
                softer.

                Centering the weight may be as much a problem as adjusting it to match
                your springs, but remember that no one can see what is under an HOn3
                locomotive's cab roof, and above the windows, unless you remove the roof.

                John Stutz
              • Bill Nelson
                My worst locomotive nightmare ever was eventually traced down to bad sprigging. I have an Ho standard gauge Gem , Little River RR 2-4-4-2,
                Message 7 of 11 , Feb 5, 2007
                  My worst locomotive nightmare ever was eventually
                  traced down to bad sprigging. I have an Ho standard gauge
                  Gem , Little River RR 2-4-4-2, Dg, CC, & W RR #21; It
                  was 10-12 years old when I got it in 1974 , but it had
                  never been run. It wouldn't run, because the spring on the
                  draw bar that rides on the tender tender pin to conduct
                  electricity to the tender had never been soldered to the
                  draw bar, and put no pressure on the pin.



                  I fixed that, and was immediately disappointed; The
                  nose of the locomotive was hollow, the lead truck carried
                  no weight, and for pulling purposes, it might have well
                  been a docksider. I built a spring to transfer weight
                  from the front of the boiler to the front truck, packed
                  the nose of the locomotive full of lead, and it went from
                  pulling 5 cars on the flat to pulling 21 cars up a 3 %
                  grade.


                  It soon started getting out of quarter. it had these
                  weird tapered axels, the likes of which I have not seen
                  before or since (thanks be to God!). It had very
                  primitives springing, steel piano wire run through holes in
                  the brass frame, and soldered in place. Have you ever
                  tried to solder steel? Well them springs would bust loose,
                  the axels would get caddywompus and get in a bind, and it
                  would twist a wheel out of quarter in a Georgia heartbeat.


                  The axels had these Humongus bearing blocks on them
                  , and it was a blue #@!% to get the axels in a
                  quartering jig, especially on the geared axels, which tended
                  to twist out of quarter more often than the others. If
                  I had a nickel for every time I have re quartered this
                  beast I could retire. I eventually wadded up some tin
                  foil, smashed it into the frame slots above the axels,
                  eliminated the sprung axels, and it has not gone out of
                  quarter since.


                  It also had another problem, the electric motor drove
                  a spur gear, which drove a spur gear on a gear tower
                  hung on an axel on the rear frame section. the gear
                  tower hung on the axel could rock back and fourth, and when
                  it did that, the allignment of the spur gears changed,
                  drastically affecting the starting voltage, so you could
                  start it once @ 30% of throttle, and the next time it
                  would need 50% of throttle. I eventually soldered a tab
                  onto the gear tower, shimmed it until the spur gears meshed
                  well, and fastened it to the frame. It took 27 years
                  to make #21 a reliable locomotive, but it gave me my firm
                  belief that no springing is much better than less than
                  perfect springing.


                  # 21 with a new motor, and all of the above work
                  still sounds horrible, like it ought to be leaving a trail
                  of brass shavings in its wake, but it is now reliable, and
                  is tied for first place in pulling power on my Valley
                  division. It doesn't like My mountain division, where the
                  combination of 18 in radius curves, and 8.5% grades causes
                  it to throw itself violently off the rails.


                  I hate sprung axels I have a NWSL Sierra RR # 18,
                  which has sprung axels which has never given me the first
                  problem, but that doesn't average out well with the 25 years
                  of problems with # 21 before I netralized it's springs.


                  Bill Nelson
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