Re: [HOn3] dcc and older engines
- 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
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.
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- 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.
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
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!
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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.
Durango in HOn3, ca. 1948
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> 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
> 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.
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
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
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.
- 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 %
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
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
# 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.