question regarding curve requirements for engines

[ondrek]

The aristo mikado says it needs a 8' Dia curve....

would the engine navigate 1 section of aristo 5' Dia curve track with out any issues?

how many sections do you suppose it would take to cause the engine to bind or de-rail due to the curve Dia being too tight?

 what about other engines?  I used the mikado as an example.  If any, that would be the largest engine on my layout, which uses 10' Dia curves and a few 8' Dia curves, but I was thinking of a spot where I might want to have the line do a little wiggle, and I only have 5' Dia curves left.

thanks

Kevin 

[cabbage]

well...

Speaking as a builder of articulated engines the problems of cornering relate to the distance between the flanged wheels. There is a simple mathematical formula that gives you the diameter of curve required for your wheels...

viz:

Radius equals 0.25 multiplied by (wheel base in inches) squared, then divided by the sum of (clearence between rail and wheel, extra gauge allowed on curve, lateral play of central axles)

regards

ralph

[two tone]

Hi Ondrek, The bigger the radius the better the loco runs, if you tried 5ft dia it would derail so go for a big radius and enjoy seeing your loco run well

[ttrigg]

I might want to have the line do a little wiggle, and I only have 5' Dia curves left.

Kevin
When doing a "wiggle" or "S-curve" you will want to make sure you have a straight section at least as long as your longest engine between the two curves.  Some of the smaller engines (0-4-0, 2-4-0 etc.) Will handle the quick change of direction with no problem.  Mid-sized and larger engines will jump track in half a hart beat on s-curves without the straight section.  I learned that one he hard way.  

I have a Bachmann "Annie" (4-6-0) that will negotiate a six ft dia curve, it complains but will do it at normal speed.  It flat refuses to do the s-curve without a straight section.

[ondrek]

there would be a straight section.

 

i'm not considering an "S" turn without a 3' section in it.  

 

I guess another way to phrase the question is....

will an engine that requires an 8' Dia curve navigate 1 section of 5' Dia curve if it has 3' straignt entering and exiting the 1 curve section?

Kevin 

[ttrigg]

If you are talking about the engine I think you are, it should do fine.  Well maybe not fine but at least ok.  The Mike is long enough so that the apparent curvature will be longer than the actual 5 ft curve.  The Mike being longer than the curve track section will have wheels on both straight sections as well as on the curve section, this will make the curve "appear" a greater diameter.  However, when the lead wheels hit the curve there will be an unrealistic some what violent jerk (depending on speed) into the curve.

[Greg Elmassian]

I'd say don't. I have one. These are long wheelbase locos. If you have curves that tight, you will probably have at least the pilot walk out of the rails. Once the loco is completely on the 5 foot curve, you will most likely have trouble. Also, if you have vertical curves you will also have trouble. Get down near the ground and sight along the boiler top. If you see it rocking back and forth, time for track work.

See if you can rearrange things to eliminate this potential trouble spot.

Regards, Greg

[ondrek]

Ok so I will stay away from a whole section of 5' Dia curve.

Most of the curves, 12 of them, on the layout are 10' Dia, but I have 5  8' dia curve sections.  I do have 1   1/3rd section of a 5' Dia curve just as a correction piece along a run of straights.   I cant imagine that its too much to cause a issue.  I will have to take a pic to illistrate what I have.

 

Kevin     

[ondrek]

OK, I got pics of my correction piece.

as mentioned its roughly a 1/3rd section of 5' DIA curve section.

having this shouldnt cause problems for engines that are requiring 8' DIA curves right?

 

 

Thanks

Kevin     

[cabbage]

Errrmmmm....

I don't know of any of my locomotives that would pass through that "curve", and most of them have 4 wheel bogies. I would suggest that you gently bend the two pieces of straight track along their length to fit your requirements at that position.

regards

ralph

[ondrek]

Serious?  its not that much, I guess what I could do is take that last extra 8'Dia curve section that I just got my hands on last night, and cut it to fit there.  Or I could try my hands at bending one of the straight sections I have.

I will work on it before I have it all down permanently.

 

Kevin 

[kstrong]

Ralph hit it square on the head. In this instance, there's no reason for such a tight section of curve. You've got all the real estate in the world for a nice smooth curve in there. By all means, just bend the two lengths of straight track to compensate, or buy a section of flex track and bend it to fit. As gentle as that curve will ultimately be, there should be no reason to even need a railbender. I think you'll be quite pleased with the results, as it will look and run soooo much better.

Later,

K

[ondrek]

Ok, I will work on that. I will see what I can do.  those are 2' sections on each side of that little curve piece, I will take one of my 5' sections and take the screws out and see if I can just curve that long section into place.

 

thanks for the inputs.

kevin 

[kstrong]

You'll probably have to cut some of the plastic webbing between the ties on one side or the other, but it should bend quite nicely.

Later,

K

[Camaro1967]

I needed a kind of abrupt curve coming out of a four ft trestle, so that it would go between some very large trees. I took a piece of Aristo stainless track, removed the tie strips, and bent the two sections around one of the trees until it did exactly what Kevin said: produced a very nice smooth curve with no sharp break.  The key is start the bend way back from where you want it to curve, make it gentle and go way beyond where it finishes. Then cut it to fit.

Paul 

[Tim&Joash&Trains]

Hi

Im new to trains, I purchased this (as in link) for my son only a few days ago and I want to put it on a track with a 36 inch diamter, the seller tells me this particular one will run OK even on a little 24 inch diameter track but Im getting a little concerned as some of these posts speak of 5 ft diameters not being enough. Will mine be ok on a 36 inch diameter?

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=110092066244&sspagename=ADME:X:RTQ:AU:11 

 

[ondrek]

Tim&Joash&Trains-

That what is in the link is a N scale engine.  what we are discussing are G scale engines.

if you are reffering to an engine that is like the one in the link but is a Gscale engine, then I am not sure what its requirements are.

you mention that you were told it would run on a 36 inch dia curve.  the smallest G scale curve is a 4 foot dia curve.  I would confirm with the store that what he meant was a 36 inch Radius curve, which would be a 6 foot Dia curve.  

that section of track that i was working on had a 1/2 section of 5 foot Dia curve.  I have since removed it and replaced it with a 5 foot section of straight track that has all the screws taken out under it, and most of the webbing of the ties cut to allow it to flex.  the section now has no indication of a curve in it at all.   Thus the removal of my pics.

What I suggest is that you  determine exactly what kind of track you have, the Dia curve pieces you have and keep to engines that will operate within those constraints.  I have, I have determinied that the mikado is out and I will be looking into the pacific, which is a 4-6-2 engine that has a curve Dia requirement of 6.5 feet.  the sharpest curve on my layout is 8 foot dia curve and most of the curves are 10 foot dia curves.  the mikado has a requirement of 8 foot and I meet that, but I am going to step down with the pacific in order to stay well within the limits of the curve requirement.

 good luck with your progress. 

 

Kevin 

[Tim&Joash&Trains]

Thanks Kevin

G scale OK, thats a big one I gather, one of the N scale i saw listed was not recommended for under 19 radius turn, anyway Ive asked the seller again just to make sure. 

Im new to this, Im trying to make a track 36 by 76 inches long and and am trying to work out where to put it so that its not too congested in our home?  I have asked the seller again to make sure he knows that I meant diameter and not radius.    Thankyou again. Any tips are valued.

Regards Tim 

[vsmith]

Tim

If your question is regarding N gauge trains, your question should really be reposted over on the Model Railroader forum, those guys know more about N and will give you better advice and more replies than here, we do da big'uns and dont know too much about da small'uns. 

[ttrigg]

Vic;
Remember, some of us used to play with the little'uns before graduating to the big'uns.

Tim;
Your 4-8-4 will work for a while on the 19 inch radius, but will wear out rather quickly.  One of my neighbors is in the process of ripping out all his n-scale curves for just that reason.  22 inch radius just looked wrong for a very similar engine.  He is moving to 30 inch radius, which we both agree looks so much better.  I would suggest that you consider "dog boning" your layout to incorporate wider sections at the ends for a wider curvature.

[Tim&Joash&Trains]

Thanks for that I appreciate your understanding even though i posted in the wrong section, I am surprised that such a tiny train needs such a huge amount of room to turn around, I think Id better make a 60 inch diameter circle for my track to do it properly. Thanks Ill go & post in the correct section next time.

Good luck with your G scale it really does sound fascinating. 

Regards Tim

[dwbeckett]

Your question is about minamum radious for engin's But if you use a critter or a lady bug you can run at 4' radious with short car's. If you intend to run any of the newer passenger car's then you will need to use as large a diamiter track as possable.