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Mass Against Speed?


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#1 Hrw-Amen

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Posted 05 August 2012 - 10:08 PM

I have now built a few engines both steam and diesel. I wanted to ask people (Especially those who build steam.) about their experiences of doing this. So far i have three MOC steam engines, (I will post my latest when Brickshelf is up.) and have used three different motor types.

First of all I built a 4-6-2 tank loco using the same wheel and motor set-up as the EN and obviously it therefore has similar performance which would be expected.

My second steam MOC is the red 4-4-0 steam engine I posted here a while ago. This seems to actually run quite well and is using a 4.5V motor and battery box (Although adapted with the PF IR unit.)it is slow, but sure, it pulls a few goods trucks (Or I guess a couple of coaches but not yet tried.) and goes at a steady rate around straights and curves through switches and the like. Slow but steady. It doe eat the batteries though, good job I am using rechargeable ones.

Now looking at photographs of steam trains I actually felt that the wheels needed to be a little more spaced out than on the standard EN set up. I decided on my latest build to try and normal train motor but with the large drivers. This is a 4-6-0 engine. I tried using the blind drivers as the middle pair but found it would not go through the switches and did not like the curves, so I have settled for using the blind drivers as the third (Rear set.) of wheels. This runs a lot better (Although still is  not too keen on switches.) but even so the motor is not that quick compared to when it is using the smaller wheels on standard LEGO trains.

So I am wondering what motor set-up do other builders of steam trains use most commonly for MOCs? I have thought about trying to get two medium PF motors into an engine but am not sure about gearing? I have built a small shunting diesel using the medium motor but it is very slow, OK for a shunter but not for a main line engine. The other solution I thought about was to construct a passenger coach (Like a baggage version.) and hide an extra motor in that to give the engine a bit of a push, but that seamed like cheating really.

I would be interested to hear what others use and what solutions you have come up with please?

#2 Duq

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Posted 05 August 2012 - 11:37 PM

For my BR65 I've used a single PF M-motor with 1:1 gearing to the Lego large drivers. The engine isn't fast but I don't mind; it's fast enough to go around with a few carriages and you can still see the drive gear working.
The typical solution for steam engine with a tender is to put the motor there but sofar I've only built tank engines. My next project will probably be another tank engine...
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#3 Icosahedron

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Posted 06 August 2012 - 12:42 AM

Well there are only two things that you can aim for with train gearing, speed or torque; not both.

If the driving gear were an 8T and the driven gear were a 24T, then the torque would tend to be about 3x more than that generated by the motor but wouldn't go fast.

If the driving gear were a 24T and the driven gear were an 8T, then the speed would tend to be about 3x more than that generated by the motor but you would have difficulties acquiring momentum.

#4 LEGO Train 12 Volts

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Posted 06 August 2012 - 05:34 AM

View PostDuq, on 05 August 2012 - 11:37 PM, said:

For my BR65 I've used a single PF M-motor with 1:1 gearing to the Lego large drivers. The engine isn't fast but I don't mind; it's fast enough to go around with a few carriages and you can still see the drive gear working.
The typical solution for steam engine with a tender is to put the motor there but sofar I've only built tank engines. My next project will probably be another tank engine...

I suggest the same solution of Duq, but if your tender is motorized you can try to regear your steam locomotive (read this two topic: BR84-009 - Post 1 and BR01-1075 - Post 52
All the best
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#5 SavaTheAggie

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Posted 06 August 2012 - 07:18 AM

With the exception of my yet to be built next project, ALL of my steam engines are tender driven.  Unless you're specifically out to get the steam engine to do the work, there's no reason to have a steam engine with powered drivers.  Personally I think, as far as LEGO is concerned, it's a novelty.  Yeah it isn't realistic, but performance is so much better otherwise.

As has been said, you can have torque or speed but not both.  My Allegheny runs on two XL motors with a 1:1 gearing to its wheels, meaning the tender wheels turn at about 200 RPM:



My PRR T1, however, is running on two 9v motors in the tender, which provides a lot of speed, but with all that locomotive in front it has to make up pulling power by serious power input (though through lubrication I've improved on that)



For my money, the best combination of power and speed comes from two standard PF motors in the tender.  My TSRR #500 is a true workhorse for me and TexLUG.  She can handle long trains and reasonable high speed.

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And if you're having problems with your ten wheeler (4-6-0), may I humbly submit my ten wheeler.  She can take all switches, curves, s curves, etc. at high speed.

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--Tony

Edited by SavaTheAggie, 06 August 2012 - 07:24 AM.

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#6 Hrw-Amen

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Posted 06 August 2012 - 11:31 AM

Thanks for the replies, maybe I will try the powered tender route, I could probably rebuild the green train to do that quite easy, apart from the tender is a three axle one, not quite sure how I'd manage that as at the moment it is the middle set of wheels that are set up to slide (So as to speak.) to enable it to go round corners. Do the old 12V 'middle' wheels fit into the middle hole in the current PF train motors as that would be an easy solution, if not I'd have to figure out how to get it round bends, maybe just give it a four axle tender?

Also, does anyone know, if I used a powered coach behind the engine rather than powering the tender, would it make a huge difference as in pushing faster/slower leading to derailment/decoupling and so on, as this would be running on standard sized train wheels whilst the main engine was running on the large drivers? Or is it such a small difference that it is likely to not matter that much?

#7 Icosahedron

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Posted 06 August 2012 - 01:10 PM

It shouldn't make a difference in speed since it's already powered, but if you pull long trains you'll need a powered coach somewhere along the line. LEGO's magnetic couplers only hold so much.  :wacko:

#8 Duq

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Posted 06 August 2012 - 09:16 PM

SavaTheAggie said:

Unless you're specifically out to get the steam engine to do the work, there's no reason to have a steam engine with powered drivers.  Personally I think, as far as LEGO is concerned, it's a novelty.
No offence Tony, but it's more than just a novelty. Here in Yurp we have these things called tank engines. They don't have a tender. If you want to model one of those you've no choice but power the drivers...
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#9 SavaTheAggie

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Posted 06 August 2012 - 09:40 PM

View PostDuq, on 06 August 2012 - 09:16 PM, said:

No offence Tony, but it's more than just a novelty. Here in Yurp we have these things called tank engines. They don't have a tender. If you want to model one of those you've no choice but power the drivers...

In spite of me being just another American, I am very familiar with tank engines.  I'd still make a powered boxcar or passenger wagon if I built tank engines.  I might build one tank engine with internal power just to prove I could do it, but that's it.  Novelty.

As to the question posed regarding powered cars pushing unpowered engines, if it were a tank engine, I.e. tenderness, it wouldn't be much of an issue.  But to push an unpowered tender engine you're better off running slow.  Trains pull better than they push, and the faster you go while pushing the greater the risk of derailment.  Unpowered tender engines would be best pushed at slow to medium speeds.

Its not really a matter of the wheels in question, but the amount of play between units.  There's always slack/available space to move built in between couplers given their nature.  Pulling removes this slack entirely (except perhaps downhill). More units ahead of the locomotive = higher risk if derailment.  

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#10 1974

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Posted 06 August 2012 - 10:26 PM

View PostSavaTheAggie, on 06 August 2012 - 09:40 PM, said:

I might build one tank engine with internal power just to prove I could do it, but that's it. Novelty.

I see what you did there ..
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#11 jmathew

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Posted 10 August 2012 - 06:09 AM

these are really nice ideas....
Thanks for sharing that...
:)

#12 monai

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Posted 10 August 2012 - 10:39 AM

everyone can do what he wants but saying that's a novelty is not very fair, for me is unusual powering a tender or, worst, a passenger car just because it's difficult to power an engine. In the wider world of train modelling the normality is a powered engine not the contrary.
You are saying that for LEGO trains is better to pull rather than push so I don't understand well your position?

The topic mass vs speed is very interesting, perhaps the philohome.com reviews can help in chosing the right motors.

regards
Sergio Monai

#13 Hrw-Amen

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Posted 11 August 2012 - 10:34 AM

View Postmonai, on 10 August 2012 - 10:39 AM, said:

everyone can do what he wants but saying that's a novelty is not very fair, for me is unusual powering a tender or, worst, a passenger car just because it's difficult to power an engine. In the wider world of train modelling the normality is a powered engine not the contrary.
You are saying that for LEGO trains is better to pull rather than push so I don't understand well your position?

The topic mass vs speed is very interesting, perhaps the philohome.com reviews can help in chosing the right motors.

regards
Sergio Monai

During my childhood days we had a layout that was 'N' Gauge in the attic at my parents house. We had quite a few steam tender locos and there were just as many that were powered by the tender as by the engine itself. So it is not that uncommon in the model train world to power tenders for these trains, or at least it was not 25-30 years ago.

I will check out the review page you mentioned to see if it will help me with my choice. At the moment I seem to have a wide variety of powered trains though, so it may come down to lining them up against one another and seeing which actually performs best.

#14 monai

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Posted 13 August 2012 - 10:47 AM

View PostHrw-Amen, on 11 August 2012 - 10:34 AM, said:

During my childhood days we had a layout that was 'N' Gauge in the attic at my parents house. We had quite a few steam tender locos and there were just as many that were powered by the tender as by the engine itself. So it is not that uncommon in the model train world to power tenders for these trains, or at least it was not 25-30 years ago.

I will check out the review page you mentioned to see if it will help me with my choice. At the moment I seem to have a wide variety of powered trains though, so it may come down to lining them up against one another and seeing which actually performs best.


I said the normality, not the rule, in small scale like the N - gauge, it is perhaps easier put the motor in the square shape of the tender, but in the gauges like 1 or G (similar to L-gauge) the engines are normally powered also with live steam...

regards
Sergio Monai



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