18"

[earthqu8kes]

can anyone make rough list of diesel locos that can turn a 18" radius. im running tight on space. can you list them if it would be protypical on 18" and if they could make it but would be atypical on 18"??? thanks

[pcarrell]

I'm assuming this is for HO?

[jeffers_mz]

Every diesel we have (about 30) with 2 axle trucks runs on our 18" curves, and they all run on 15" curves too. The Genesis F units are right at the edge of possible performance on 18" curves, until you grind a little material off the back of the grab iron stirrups that interfere with the brake arm on the trucks. Once done, they handle 15" curves with ease.

Per other modelers, many 6 axle diesels work well on 18" curves too, but we don't have any of those so you'll have to wait till people who own them come here and post, or else search "6 axle" and "18 inch", and variants there-of.

[spidge]

Go N-scale and there is no problem.
Just kidding. Stick mostly to 4 axle units as the six axle units wont look as good and even if they will make the turn they will have difficulty with any turnouts as they come out of that turn. I say this because without some simple standards and restictions your layout will not operate reliably, NO FUN!

[MisterBeasley]

I've got a P1K Alco RS-3 with 6-axles, and it takes all of my 18-inch curves just fine.

[spidge]

Its a matter of preference. If you have high benchwork then you will not notice the larger overhang on the longer locos.

[tomikawaTT]

The bad news is that NO model diesel currently available looks 'prototypical' on 18" radius curves, with the possible exception of an EMD SW unit.

The good news is that almost anything available can take an 18" radius curve, with the possible exception of an EMD P unit.

The best way to deal with the first xxxxxxx, er, opportunity, is to hide things so those tight curves can't be seen from the outside. Buildings, a microforest, even a large billboard can do wonders. From the inside, the overhang isn't that noticeable.

Do be aware, though, that overhang may force you to move some details like relay boxes, signal masts and crossing gates farther from the centerline of the track. This is a good spot to measure carefully before installing.

Chuck (who runs some 14" radius curves - with very short rolling stock)

[bogp40]

The 18" really limits your eventual roster. Even though the equipment may just make it , you are opening yourself up to all sorts of future troubles. The appearance of even shorter rolling stock pulled by 4 axle locos just doesn't look right. If you can, try to use at least 22-24" you won't regret it. If it means even adding a 4-6" section just at the widest portion to accomadate the increase try it. Your entire benchwork doesn't have to be increased only the area for the track. Creative scenicing can make it blend as well as curving the facia.
Bob K.

[jeffrey-wimberly]

All my locos run on 18" radius. My smallest is the Athearn F7 and the biggest are the Athearn PA-PB and the P2K PA.

[ezielinski]

All my motive power runs reliably on 18" curves, including Dash 8 and Dash 9 CWs, SD45s, and SD50s. I feel more comfortable with the appearance of my 4-axle diesels though.

[earthqu8kes]

could an SD40-2 or SD45T-2 take a section or two of 15" curves. i have a really small space so i have to use a section of 15". i may be able to modify but im not sure...

[ezielinski]

I have an SDP40 (Athearn). I am at work right now, but I will try it when I get home and let you know.

The potential problem would be how much of a difference there is in truck travel/swing between manufacturers.

[ezielinski]

I just got home from work and tried it. An Athearn SDP40 will take a 15" radius curve, but only up to a 1 percent grade. Any more of a grade and the leading truck will come off the rail. If you are running "the flat", it should take it without a problem.

[earthqu8kes]

thanks i am thinking of getting a athearn sd40 or sd45... the 15'' piece of track is level so it should be fine.[:D]

[Texas Zepher]

The only issue isn't just the locomotives ability to take a corner. It also has to be able to pull a train around that corner. Depending on how the couplers are mounted and pivoted will make a big difference.

Example - I have an Altas RS-3 (one of the originals with Kato drive) that I thought would work really great on a small demo switching layout. There was only one real "curve" in the thing. The Atlas RS-3 couplers are body mounted, the pivot point is right on the end of the frame, AND the trucks are mounted fairly far toward the center of the loco. This makes the coupler swing WAY out and it would "tip" the cars sideways off the track that it was pulling or pushing through the curve.

[rayw46]

Many of the 6 axel diesels will take an 18'' radius curve, maybe even a 15" radius, but will they stay coupled, especially to a 60' or longer car? Chances are, no. On my small layout I have a mimimum radius of 22", but I do use Atlas #4 Code 83 turnouts. My 6 axel locomotives have no problem negoiating these turnouts.

[chateauricher]

earthqu8kes,

It would really help if you mentioned what scale you're working with. It makes a huge difference. 18" radius curves are great for N-scale; but tight for HO.

[earthqu8kes]

QUOTE: Originally posted by earthqu8kes

could an SD40-2 or SD45T-2 take a section or two of 15" curves?

if you read some of the other posts carefully, you could tell im talking about HO... sd40's can easily take 15'' curves in Nscale...[;)]

[Metro Red Line]

If you only have room for 18" radius, I would make two recommendations for you:

 

1. Limit your locos to 4-axles and your rolling stock to 50'

2. Switch to N scale.

18" radius is a horribly outdated holdover from the 1950s era and HO train sets (Tyco, Bachmann, AHM, Life-Like all sold their train sets with 18" radius curves). But all train sets had truck-mounted couplers.

If you're a little more serious about your modeling, 18" radius - unless you're modeling a narrow gauge line or a 1950s era short line - is a horrible curse. Even serious HO modelers think 22" radius is too tight! Look at all the HO layouts that get featured on MR....their minimum radius is 30" and higher! 

If you like to run 6-axle locos, Superliners, Auto Carriers and 89' piggyback flats, 18" will not cut it.

I made the mistake of building my last HO layout with 18" curve snap-track. Eventually some equipment would just not run. I had to return a set of Walthers intermodal well cars that were connected by drawbars because they only run on 24" radius and higher. And even if they could navigate the curve,  sometimes cars would take a tumble on the grades. I learned the hard way that it is IMPOSSIBLE to have a good modern-era HO scale layout with 18" radius curves. 

I finally dismantled my HO layout a couple months ago.

I have since converted to N scale and pared my 4x12' HO layout into a similar trackplan in a 4x8' space. This time, 18" radius curves look just graceful.

With everything RTR in HO scale these days, there's barely any price difference between HO and N.

 If you really want to stick with HO, then junk the home layout and build a nice display case. Join a club if you want to run your trains - they all have nice broad 30" and higher radius curves.

[Leon Silverman]

Many of the 6 axel diesels will take an 18'' radius curve, maybe even a 15" radius, but will they stay coupled, especially to a 60' or longer car? Chances are, no. On my small layout I have a mimimum radius of 22", but I do use Atlas #4 Code 83 turnouts. My 6 axel locomotives have no problem negoiating these turnouts.

 Six-axle locomotives can probably remain coupled to thier train if they have truck mounted couplers.  A six-axle locomotive with body mounted couplers probably will not remain coupled to the train unless you have a transition curve (gradual change of radius.  Rather than requiring adding a foot or so to the width of your platform that would be required to accomodate a 22 or 24 inch radius curve, a transition curve would require only an additional one or two inch spacing between parallel straight tracks (The centerlines would be 37 or 38 inches apart instead of 36 inches.).  

 

[Anonymous]

I have a couple of 2 axle indutrial switchers and they look good going anywhere. I have a few peices of track that are labeled with 12 3/4" radius (made by Jouef in France) and my switchers take the curve just fine.

[Metro Red Line]

I have a couple of 2 axle indutrial switchers and they look good going anywhere. I have a few peices of track that are labeled with 12 3/4" radius (made by Jouef in France) and my switchers take the curve just fine.

 

If that's all you'll be running on your layout, then those tight curves will do just fine.  

[bigbnfan]

OK, a few things

 

a) Pick an early modeling era. I do 1970s, and occasionally run a SD40-2. it just handles the curves

b) try and forgoe passenger services. if you MUST, do passenger, pick shorter than scale length cars, and 4 axle F Units, and, with one exception, no F45's.

Also, do short cars to. even with body mounted couplers, they run fine.. no longer than 50 foot boxcars

 

follow these tips and you should (read: should) be fine