One small complaint that I have about MODEL RAILROADER's engine reviews is
that they will talk about an engine like it has a lot of power but when you
look at the drawbar pull vs. the "average" locomotive, it is often much
weaker. While I like nice looking engines, I also want to know how they
pull. What is an "average" locomotive anyway? : )
Yeah, the "average" thing is kind of lame. If you look at the small
print describing the graph, it explains that the average is just a real
average of several previously reviewed locos (of the same type as the
And they don't really say if the "same type" is just diesel or steam or
do they break it down further into number of axles, etc.
So, if they reviewed few really heavy locos lately, the average would
be quite high. I think it is really pointless fluff.
Didn't the recent review of the Bachmann 2-10-2 say something about it be
ing a real drag engine? The first line in the review reads, "This powerful
HO 2-10-2 may be called a "light" 2-10-2, but it's still a big steam
locomotive by most model railroad standards." Yet, it is about 1.5oz. less
than the "average" in terms of draw bar pull.
Shows how believable the MR advertisements, sorry "reviews" are when on
Bachmann's own board people are complaining about how this loco can't pull a
decent train and has a tendency to derail. No mention in the MR review of
any of that, nor that fact that the loco though advertised with Walchearts
gear comes with Southern except one road name that comes with Baker.
Home of the Great Eastern Railway
Model locomotive pull is proportional to weight. Heavier locomotives
pull more. The motors always have enough torque to spin the wheels, so
tractive effort is limited by the onset of wheel spin. For metal wheels
on nickel silver rail, the coefficient of friction is about 0.25. The
means the wheels start to slip when the tractive effort is 0.25 *
locomotive weight. So a 16 oz locomotive can create 4 oz of draw bar
pull. Double the weight and you double the draw bar pull.
The only way to improve on this is to improve the coefficient of
friction by the use of rubber traction tires. Rubber on nickel silver
has a coefficient of friction of 0.5 or better, so you get double the
pull for the same locomotive weight.
HO diesels pull better than HO steamers, especially plastic HO
steamers. All my diesels pull enough cars up my grades. None of my
steamers pulls as many cars as I would like. I have packed as much lead
as will fit into all of them, and they still don't pull as much as I
If you like steamers, consider keeping the grades gentle to give your
locomotives a break.
If they would start using lead again for the weights it would help a
lot. However it would then take the model out of the TOY class and I
suspect affect a lot of things from sales points to EPA problems.
Steel tires would also help some. I remember the brass comments always
used to be when the nickel wore off and the brass showed the pull would
Prototype diesels pulled more than prototype steamers, too. Not that it
matters much, since other factors determined the locos' actual tonnage
rating. For both, grades severely reduced ratings. 1% generally cuts the
rating in half - that's why real railroads tried to keep grades well
below 1%, and mountain lines bought huge locomotives. Recall that the
biggest engines of all, the Big Boys and the Yellowstones, were built to
haul 5,000-10,000 ton trains on grades of about 1%!
A locomotive's tonnage rating was what it could pull _safely_ over the
route it was assigned to. The same loco could have very different
ratings over different divisions, even with the same ruling grades.
Example: the Huron Central operates between Sudbury and Sault Ste Marie.
It's a very hilly line. Trains are generally around 50 cars, hauled by
four rebuilt GP-40s. That's 10,000hp for a 4,000-5,000 ton train**. (The
Big Boy rated about 6,000hp.) 50 cars stretch about half a mile. The
line has many short but relatively steep hills, with little or no level
stretches between crests and troughs. That makes train handling tricky;
it's easy to pull train apart on such a line. Those four GP-40s are
needed as much to provide good braking as pure haulage.
IOW, modellers tend to overestimate tonnage ratings, and so often think
a perfectly prototypical train is too short. Especially on grades.
**I'm assuming the rebuilds have been downgraded from 3,000 to 2,500hp.
Well, this is said a lot, and it probably should be qualified somewhat.
A one-pound model diesel with all axles powered and a one-pound
model steamer with all drivers powered (such as an 0-6-0), equal
motor powers, and equal drive efficiency and gear ratios, both with
nickel silver tires, will pull the same number of cars on straight
Increase the grade, and both will lose the same amount of pulling
On curves, the diesel will likely pull slightly better, because it has
shorter rigid wheelbase (the truck wheelbase) than the steam engine.
Add leading & trailing trucks, and the steam engine will not pull as
well, as some weight has been lifted off its drivers. The more weight
the trucks carry, the less tractive effort the model can develop.
I suspect a lot of the 'model steam engines pull less' belief comes
the usual equivalence of two or three model diesels to one model
steamer at the head of a train. Very often these several diesels
together carry a much greater weight on drivers than the single steam
loco they substitute for. I think we do this because steam models cost
more than diesels, and diesels look much better in groups than alone,
especially cab units.
Plus, the plastic steamers lack the internal volume to carry enough
ballast to make them as heavy as the typical road switcher. Especially
the small ones. I have a pair of plastic IHC Moguls, tiny engines,
small diameter boilers, which are completely filled with factory weight.
I couldn't find anywhere to stuff in more weight. My Bachmann Spectrum
Consolidation is bigger, and hence heavier than the Moguls, and it pulls
The older all metal Bowser and Mantua steamers are heavier than the
new highly detailed plastic ones.
You might try carving out the factory zinc weights and replacing with
home-cast lead weights, as lead is about 1.7 times as dense as ZAMAC
alloys. Wasn't there a thread about tungsten weights a while back...?
alloys. Wasn't there a thread about tungsten weights a while back...?<
True if we got rid of Zamax as weight and used lead it would be better
but then there's EPA. I checked on Tungsten and if you can find it the cost
is extremely high. I tried various stores that deal in reloading but all
they had was boxes of ammo and the cost was very high but then it was big
game ammo. It's probably as easy to get depleted uranium* as tungsten!
* This was used in some N scale engines and it really works <VBG>.
Now we don't want to reactivate THAT old argument, do we now?
Anyway, model trains are nominally toys, which probably is why the mfrs
don't use lead...but it's still quite usable at home, unless you're in
under heinous EU overregulation.
They say you can get tungsten welding rod rather easily.
I don't know if this is so.
What is tungsten welding rod made of? Also what do rather easily mean,
any welding supply store!
Not sure what you meant by "old argument" but if in reguards to depleted
uranium it's available but I found out it's not like lead (soft) but a very
hard metal so shaping for weight is not very practical.
Well, I did some research. Tungsten *electrodes* (not welding rod, my
mistake) are available in 10-packs for about $30 at welding supply
in several diameters, about 7" long. Found here:
Gosh, this is darn pricey...lemme give some info I found then look for
They are for TIG welding (tungsten inert gas) also
known officially but not really to anybody as GTAW (gas tungsten arc
(GTAW and GMAW are 'more neater' acronyms for TIG and MIG welding,
but the problem is you just can't pronounce 'em as nice.) TIG welding
uses a 'nonconsumable' tungsten electrode torch, a shielding gas like
MIG welding, and separate filler rods made of the weld metal. It's
common in industry.
Pure tungsten electrodes are available, as well as rods mixed with
(radioactive) or nonradioactive rare-earth metals to retard evaporation
increase conductivity, neither of which is important to us, so the pure
is better. It can be cut with normal HSS tools. Solid tungsten has
times the density of lead; I did some quick calculatin' and a close
of 1/8" diameter electrodes will have 1.5 times the density of solid
or 2.2 times the density of solid steel or zamac (which are similar in
Incidentally, a similar close pile of 1/8" diameter solder has 1.3
density of a solid chunk of steel that fits in the same place.
Hmmm....Osram Sylvania, the lightbulb people, makes W rod...
Anybody care to call for a quote and/or split a multi-ton minimum
Now this might be a better supplier:
Gotta love a metal dealer that has 'Tungsten Fun Facts' on their site.
Or better yet, how about finding a foundry that will cast the stuff into
shapes more useful for weighting locos, like bars or chunks? Hell, the
molds would be super-simple.
Probably a ton or two ought to be enough ...
I think someone should unplug the entire Internet and let us start
all over again. This time, make sure that Sergey Brin, Larry Page,
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