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For pulling POWER diesel or steam?

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cape cod Todd

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Discussion starter · #1 ·
Howdy All
Question for sheer pulling power what is the best way to go diesel or steam? I really like the look of steam engines and all the bits and pieces of mechanical ingenuity that makes them go not to mention the character of a steam engine that the new diesels just don't seem to have. I have several steam engines, I should say electric that looks like steam, including a shay, heisler and climax. Love em but even they seem limited in their pulling power. I have had my eye on a USA trains GP30 for some time now in the Chessie colours but how good is it? How does USA trains stack up to Aristocraft? I have some 5' diameter curves on my layout so I need to stick with a 4 wheel engine versus a 6 wheel else I would go for a SD 45. I do have grades approaching 3% but say we put a 38 ton Shay and a GP30 next to each other on flat level track which will be able to pull more cars? Which is more likely to slip and possibly damage gears? Trying to get parts for a shay is very difficult but I would assume not so hard for a USA or Aristo. I'm looking for a workhorse engine that will haul around a track cleaning car etc... that I won't have to worry about destroying.
 
Discussion starter · #3 ·
Dual powered units sound good Livesteam53 but for over $700!! That's too rich for my poor RR. Plus I like the style of the GP series engines, and I like even better that they are not much more than $200. They do have 2 motors but weight and traction are also factors in the pulling power arena. Does a geared Bachmann loco have better power than a 2 motored diesel GP30?
 
#4 ·
My most impressive pullers are my e8's, although I don't have a SD45.

I remove traction tires, so my USAT diesels don't have much pulling power, I figure mostly because they weigh less... simple physics.

I'm not sure that my non-ball bearing USAT locos will stand a lot more weight, but with the ready availability of USAT wheelsets, I think I will give adding weight a try.

Regards, Greg
 
#5 ·
The formulae for working out the effective effort of a model locomotive have been around since 1904. Basically for each Kilogramme of weight that is taken by the driving wheels 230 Grammes of that is available for traction, So, in a C0-C0 loco that weighs 5 Kilogrammes, 1.150 Kilogrammes is the maximum tractive effort. While for an A1A-A1A loco, 766 Grammes would be the maximum. Electric traction motors develop their peak torque at far lower rotational speeds than a steam loco using pistons, thus pull better at lower speeds. The P.L.A.N. formula gives the peak power of your steam loco -but this does not really work too well at Gauge 1 and smaller scales... A more accurate formula (or rather less inaccurate!) is to use simple physics and ignore adiabatic and isothermal effects and treat the system as one under constant thrust with no lead and lap effects.

regards

ralph
 
#6 ·
You missed the coefficient of friction being different for traction tires I think.

With the suspensions on model trains, I don't think we get anywhere near theoretical.

By simple empirical evidence USAT locos pull more with traction tires than without, no other changes.

Regards, Greg
 
#7 ·
Whoa!

Steam pistons???? Steam outline electric drive.... wrong apples....
If you are comparing 2 motor dismals then perhaps an articulated w/ 2 motor blocks is the model to compare.... ignore the pilot and pony trucks, they don't carry a scale load, if you use Ralph's logic.

John
 
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#8 ·
In this instance, I would say anecdotal evidence is going to be more reliable as an indicator of which brand and type of Large Scale locomotive pulls the most cars.

Dave Goodson has first hand experience of a battery powered R/C controlled early Bachmann Shay hauling 30 + pieces of stock up a 4 % grade. Of course the plating was worn off the wheels which aided adhesion and thus hauling power.
 
#10 ·
I had an aristocraft Pacific which was an excellent puller. I cut it down to make an Atlantic out of it (4-4-2 instead of 4-6-2) and it pulls better as an Atlantic. The weight is the same, so I can only figure it's because the shorter wheelbase tracks better through curves. The Atlantic is a better puller than my Aristo Rs-3.

I believe in real life that the bigger steam engines,like the northerns, were far better individual pullers than the diesels that replaced them, but the diesels were far better in terms of maintenance costs and ease of consisting--three Rs-3s were cheaper and more effective than one northern
 
#11 ·
Yes Greg....

I did use the standard figures for steel to steel rather than steel to A.N.OTHER -this is because I cannot define what the coefficient of the frictive medium used for the tyres(!) The suspension does not really affect the tractive effort -but does play a part in how the power curve is delivered to the track. At a constant speed the suspension does not affect the tractive effort -but while the loco is applying power and braking with its motors then "tramping", "rearing" and "shimmy" of the drive wheels to the rails should be absorbed by the suspension and the stored energy returned to the direction of thrust.

UK Railway Terms Glossary:

Axle Tramping = the action of the driven axle gear wheel to force one side of the axle into the rail lowering the load on the wheel at the other end of the axle -sometimes to the point where the wheel will lift off the rail.
Bogie Rearing = the action due to "weight transfer" during load and braking in which the transfer can lower the effective weight on a bogie causing the flanges on the wheel to climb the rail.
Wheel Shimmy = the action of a wheel when changing speed to act as a gyroscope and present a precessional force to the bogie -causing the wheel to lift especially while cornering.

regards

ralph
 
#12 ·
Weight on drivers times .23, eh? An interesting bit of information to have handy. Perhaps it may vary a bit for brass wheels or plating.
 
#13 ·
Thanks Ralph.

Actually the coefficient of friction should only be related to kinetic friction, not static friction.

My point, which may not have been obvious (but I knew Ralph already knows) is that with the suspension and bumping around, our locos may be in a state of kinetic friction even when starting out (occasional wheelslip) because of the suspension causing intermittent contact with the rails.

Kinetic friction is lower than static friction.

But just us physics-heads worry about stuff like this.

I'm in the general frame of mind that - as Tony says - the empirical (he said anecdotal, same meaning here) evidence is probably the best to go by.

Regards, Greg
 
Discussion starter · #14 ·
Wow alot of great answers here from some very intelligent people that have actually gone way beyond my original question and my understanding.
I'm not a rocket scientist after all! LOL
But really to rephrase my question removing the real world friction ratios etc... What pulls better right out of the box with no modifiications, is more reliable with less maintenance and less worry about blowing out a gear, a bachmann shay or any of their geared loco offerings, a USAT GP 30 or GP38 2 motor diesel, or an equivalent 4 axle aristocraft diesel style engine?
And if i could add in one other question... which is easier to convert to battery power, a steam or a diesel? I would suspect the diesel.
Thanks for your answers.
Todd
 
#15 ·
I don't have a 4 axle Aristo with the new prime mover (only the GP-40 is in this class).

I've had poor luck with the other Aristo 4 axle trucks, I think the older (bearings in sideframes, sprung) style were more rugged than the newer style. But I think they pull better than a USAT 4 axle that has no traction tires.

With traction tires, the USAT will pull better, but you might get a split axle. Notwithstanding that, I think the USAT 4 axle trucks are lower maintenance.

The bachmann products all have split gear or other problems, even though the shay is quite a puller.

If I wanted the lowest maintenance best 4 axle puller I would get a GP-40.

Next choice would be an RS-3

If the criteria was only pulling power, a USAT 4 axle with traction tires (but my experience is more maintenance)

It's not as simple as a go no go here. Also, you have mentioned 1:20.3 and 1:29 locos.

On the easiest to convert... Aristo locos with a socket.... take your pick, they are all dead easy.

Regards, Greg
 
#16 ·
The new Shay trucks are reportedly quite good. I don't have one myself, so I'm left to go on the experiences of others, but from what I'm led to believe, the "new" truck design fixed the issues that plagued the original model. Those who run them have demonstrated them to be very good pullers. (While chasing down a rampant spammer this morning, I came across a post from someone using his Shay to plow snow. If anything's gonna stress your gears, it's that.) I've got a B'mann Heisler, and it's been beautifully reliable for coming on 7 years now. I've never physically tested its pulling power, but it's certainly demonstrated no lack of strength that I've seen. The Climax is a lighter locomotive than either the Shay or Heisler, so I'd be led to believe it's not quite as strong a puller, but not having one to compare, that's just speculation.

In terms of converting to battery power, given the options you're looking at, I'd say the diesels would probably be a bit easier for no other reason than you've got the benefit of the entire hood to play with for room. The Shay's bunker is a bit smaller, and your Tetris skills will come into greater play.

Later,

K
 
#17 ·
I'm testing my new "Big John" Dunkirk Geared Locomotive by Hartland Locomotive Works, (HLW), made in the USA, warranteed for one year or 800 hours commercial use. It was pulling a heavy sound box car plus 11 tank cars with steel wheels and a caboose up a 2 percent grade all day and evening last Thursday. Iit's kinda ugly but powerful with a motor in each truck and sells for around $300 depending on the deal. It's not a diesel but so far so good.
 
#18 ·
I would have to second Ron's recommedation, the Hartland "Big John" has got to the most unheralded LS work-horse
ever built, have one here that has about 4,000 hours on it, an it'll still pull the house down...
Paul R...
 
#19 ·
For converting to battery power the diesel would be easier due to having a bit more room to work on and maybe hold the battery. You could also build a battery car and put it behind the steam loco and then not worry where the battery goes.

Far as the 4 axle diesels I'd go with the AC GP 40 due to not having to deal with USAT traction tires and then worry about gear problem coming loose from the axle if you over tax the unit. Later RJD
 
#20 ·
While dismals have hoods, Steamers have tenders and empty boilers. In my small 2-8-0 the batteries went in the boiler and the electronics in the tender. To make up the weight I added lead shot where ever I could. She pulls the same as before....
 
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