MR engine reviews

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? : )
dlm --------------------------- Dan Merkel
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Dan Merkel wrote:

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 current one).
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.
Peteski
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Which nicely sums up ALL MR reviews.
-- Cheers
Roger T.
Home of the Great Eastern Railway http://www.highspeedplus.com/~rogertra /
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An interesting comment.. can you (or anyone) give specific example(s) of a review like that? It sure sounds like they are misleading us.
____ Mark
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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.
dlm

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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.
-- Cheers
Roger T.
Home of the Great Eastern Railway http://www.highspeedplus.com/~rogertra /
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Dan Merkel wrote:

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 would like. If you like steamers, consider keeping the grades gentle to give your locomotives a break.
David Starr
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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 increase.
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David Starr wrote: [...]

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.
HTH
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David Starr wrote:

Dave:
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 track. Increase the grade, and both will lose the same amount of pulling capacity.
On curves, the diesel will likely pull slightly better, because it has a 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 from 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.
Cordially yours: Gerard P.
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snipped-for-privacy@gannon.edu wrote:

All true. 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 better too. The older all metal Bowser and Mantua steamers are heavier than the new highly detailed plastic ones.
David Starr
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David Starr wrote:

Dave:
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...?
Cordially yours: Gerard P.
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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>.
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Jon Miller wrote:

Jon:
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 Europe and under heinous EU overregulation.
They say you can get tungsten welding rod rather easily. I don't know if this is so.
Cordially yours: Gerard P.
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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.
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Jon Miller wrote:

Jon:
Well, I did some research. Tungsten *electrodes* (not welding rod, my mistake) are available in 10-packs for about $30 at welding supply stores, in several diameters, about 7" long. Found here: http://www.weldingsuppliesfromioc.com/servlet/the-1239/TUNGSTEN-ELECTRODE--/Detail
Gosh, this is darn pricey...lemme give some info I found then look for a cheaper alternative...
They are for TIG welding (tungsten inert gas) also known officially but not really to anybody as GTAW (gas tungsten arc welding). (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 very common in industry.
Pure tungsten electrodes are available, as well as rods mixed with thorium (radioactive) or nonradioactive rare-earth metals to retard evaporation and increase conductivity, neither of which is important to us, so the pure W is better. It can be cut with normal HSS tools. Solid tungsten has ~1.7 times the density of lead; I did some quick calculatin' and a close pile of 1/8" diameter electrodes will have 1.5 times the density of solid lead or 2.2 times the density of solid steel or zamac (which are similar in density).
Incidentally, a similar close pile of 1/8" diameter solder has 1.3 times the density of a solid chunk of steel that fits in the same place.
Hmmm....Osram Sylvania, the lightbulb people, makes W rod... http://www.sylvania.com/BusinessProducts/MaterialsandComponents/MolyTungstenPowderParts/TungstenRodandWire/TungstenRod /
Anybody care to call for a quote and/or split a multi-ton minimum order? ;-)
Now this might be a better supplier:
http://www.eaglealloys.com/tungstenalloys.html
Gotta love a metal dealer that has 'Tungsten Fun Facts' on their site.
Cordially yours: Gerard P.
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snipped-for-privacy@gannon.edu spake thus:

http://www.sylvania.com/BusinessProducts/MaterialsandComponents/MolyTungstenPowderParts/TungstenRodandWire/TungstenRod /
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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David Nebenzahl spake thus:

Or better yet, seriously: just get bar stock instead (the Eagle Alloys website says they have that in various sizes) and cut and stack it.
--
I think someone should unplug the entire Internet and let us start
all over again. This time, make sure that Sergey Brin, Larry Page,
  Click to see the full signature.
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1. What are HSS tools?
2. If it is rod shaped, wouldn't be pretty easy to drill holes in the original seight then simply insert a short piece of rod?
dlm

http://www.weldingsuppliesfromioc.com/servlet/the-1239/TUNGSTEN-ELECTRODE--/Detail
http://www.sylvania.com/BusinessProducts/MaterialsandComponents/MolyTungstenPowderParts/TungstenRodandWire/TungstenRod /
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Dan Merkel wrote:

High Speed Steel. Dremel cutters are made from HSS. It stays sharp when hot longer than plain carbon steel.
David Starr
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