4-8-4 that can take small radius curves? (HO scale)

Model Railroader General Discussion (Model Railroader)
1

I’d like to get a 4-8-4 (ATSF) steam locomotive for the HO scale layout.

There are two that I’m looking into. The BLI Santa Fe 4-8-4 and the Bachmann Santa Fe 4-8-4. I’m not sure which of the two can take tighter curves. Possibly the BLI since it is a shorter prototype, but that is just a guess.

Factory installed DCC/Sound (BLI) is not a major priority since I would likely change to Soundtraxx Tsunami anyway.

Unfortunately I’m not sure what the tightest curve is on the layout. My dad installed the flex track back in 1973 and made the curves to fit the layout. So I don’t really have a number to give on the curve radius. But I know that I cannot run an Alco PA without it derailing.

Any ideas which 4-8-4 might work better for me? Or of a way to measure curve radius on already installed track?

2

Matt,

If you can’t run an Alco PA w/o derailing, I think you’re going to be frustrated if you purchase a 4-8-4…or - at the very least - flirting with disaster.

Tom

3

Sounds like there’s some 18" or even less on that layout. I would check those tight turns and see if they can be relaid. It is possible that you have only a few turns that may be trouble. I don’t have either of these engines so can’t be of help as to which one would negociate the tighter radius.

4

I can run a couple of Bowser 4-8-4s on my layout with 18" curves. The center drivers are flange less.

P2k SD 60s, Kato SD 40-2s will run all day with no problems. Either you have less than 18" curves or the PA has wheel gauge or some other issues.

Get a piece of 18" sectional track and compare.

5

Hmmm, yeah it makes sense if the PA has trouble that a 4-8-4 would be worse. And it is likely that some curves may be tighter then 18", especially on the inner track. So I might just stick with my Bachmann 2-8-0 as my only steam loco for now.

It would not be easy to relay the track to ease curves as the terrain and town and everything else are pretty much set and in the way. This photo will give you an idea of the HO layout and the tight curves:

At least I can run steam on my outdoor G scale layout. I laid the tracks for it and the curves are wide [:D]

6

Matt

You did not say what your minimum radius is. The Bachmann should take tight radius better than the BLI.

You can use a string and using a pivot point about 18" out from the middle of the curve, swing the other end around adjusting the length of the distance from the center until the arc from the curve traces the curve. Try starting the pivot point about 18" out for the first swing and adjust as needed to find the basic curve. There may be other ways better, but this will get you into the ball park so to speak.

After looking at the layout, it would seem the radius is very tight and most steam would have trouble.

CZ

7

I have both of those Northerns, and I much prefer the BLI version over the Bachmann version which is not up to the quality of the Spectrum line. The Bachmann is too light, especially in the tender.

I run mine on 30" and 32" radius curves. My old layout was 22" and 24" radius curves, and that was a challenge for the 4-8-4’s, but you can do it with bullet proof track work and slower speeds.

Can you estimate the minimum radius of your curves? Pick up a few 10" Ribbon Rail Track Alignment gauges and use them to determine the approximate radius. Or, trace the rails on parchment paper by running a pencil over the rails and mail it to me and I can tell you the radius, anywhere between 22" and 40" radius.

Rich

8

Do the passenger cars shown have any problems?

9

Not those (Train Station Products) in particular but the new replacement Hi-Levels I got from Walthers would not make it around the layout without derailing in the curves.

I had to change the trucks on the Walthers cars to Train Station Products so the couplers could be truck mounted. I think this is called Talgo? They work fine now with truck mounted couplers.

10

That makes sense. I would check the radius with whatever method you like and if less than 18", forget it.

If 18" or better give BLI and B man a shout and see what they say.

Better to be sure before you buy an expensive static model.

11

Most any x-8-x will demand the two center drivers to be blind drivers to handle any tight radius curves. Then there is a realistic tender clearance that won’t force a binding event derail as the tender hits the cab. Often such setups have to have ugly tender clearances with 8 foot scale separations to make tight curves. The whole effect hails back to the toy tinplate trains under x-mas tree layout and absurd looking operation.

Mate the motive power, to the curves for realism, if the road is already built.

Richard

12

I’m pretty sure the Bachmann 4-8-4’s all require 22"R curves. The Walthers’ passenger cars are recommended to have 24"R or more.

You could re-do your layout in the space to have larger curves, but you’d have to re-do a lot of your scenery.

13

My bet is that the Bachmann is engineered to take tighter curves than the BLI, and that the BLI will maybe go around 18" curves slowly and if they are perfect. Any imperfections, say being level across the rails at any one point on the curve, or just a tad tighter in part of the arc than the claimed 18", and you can make friends with misery.

Having used several issues of the Walthers longer passenger cars, their 24" minimum radius is for the truly skilled and patient track layer who can lay curves close to perfectly. And even then, the odd car will require some fine tuning of the trucks, scraping or filing the frame or car body details, and the installation of a longer shank coupler. I tell people new to track laying in general, and to the longer Walthers passenger cars, that they are inviting heartache if they use curves much less than 27" radius.

Crandell

14

According to the Bachmann Trains “big book of trains” their 4-8-4’s {as well as 2-8-4’s} should “run on 22" or larger curves”.

That is Bachmann’s own recommendation.

They MAY actually navigate the smaller R curves, BUT…

So I would suggest going with a smaller steamer for those tight curves.

[8-|]

15

Matt, first, good looking layout.

Second, you really need to figure out the radius. Is the tighter turn a smooth radius? What I mean by that is the angle of the turn the same all the way around? In the picture it looks like it gets tighter in the center. If it is the same radius all the way around the turn, the essayist way to find out the radius is, is to measure across the U part of the turn. You need to measure from the center of the track.

Take the distances it takes to turn around and dived by half. If it takes 36 inches to turn 180 digress, it is a 18 inch radius. 30 inches it is a 15 inch radius and so forth.

Now for a rant on my favorite subject! [soapbox] You Don’t Have To Have 22 Inch or Bigger Radius Turns To Run Steam Or Big Diesel Power! My layout, as case in point. I still have 3 18 inch radius turns that are hidden. Yet I can still run steam and 6 axle diesels.

BLI Steam. M 1 A , Heavy Mike and Class J. All so have a Hudson but it only has 6 drive wheels.

Bachmann 2 GS 4.

Mehano Santa Fe Type 2-10-2.

6 Axle Diesels

Erie Built, GE AC 6000’s, RSD 15, E-6’s, E-8, FP 45, SD 50’s, SD 40-2, SD 7 and a few more than I am forgetting about.

Then the BIG Engines, Y6 b and the Big Boy.

2 Main Keys.

1 If the Manufacturer recommends a 22 inch turn, don’t buy it if you have 18 inch turns. Reason I never bought a Bachmann Yellow Stone. [sigh]

2 Have to have smooth and well laid track your!

With the age of your track, check for dips and high spots and if the rails ends are even!

One last thought, on the PA that wont make the turn. Is it by chances a Athearn Blue Box? Reason I asked is I had a Blue Box FP 45 that would not take a turn? Seems the front truck was hitting the ladder and caused it to derail. While the FP 45 is not a PA, I have a few PA

16

Thanks for all the replies.

Alco PA

The PA is an older Life Like Proto 2000. Beautiful lash up (ABA) but it doesn’t like some of my curves. I was able to widen one curve out in the desert portion and the PA lash up works through there after the track mods. So it’s not a truck issue but a tight radius issue. The wheels are all in gauge too.

While a large steamer would be nice, I have to be realistic with what I have. With the track as is I just don’t think a 4-8-4 would work all that well.

Thankfully F units work well on the layout. Otherwise I’m not sure what we could run.

17

Have you tried running them 1 at a time? If so, with out the shell?

Reason I ask, my PK 2000 SD 7 would not take the turns with the shell on. I tried it with out the shell and it was no problem. Steps in the front needed a little sanding so the truck would not hit them

Reason I asked about running them one at a time. On my Dash 9’s (I knew I for got some) and GE AC 6000’s the normal Kadee couples where to short and caused derailments. Went to longer shanks and no longer a problem.

Just trying to help.

Cuda Ken

18

Just guestimating but it looks like the outer curve on the left side is maybe 18", the inside one is much tighter. However, what is the outer, wider curve on the left becomes the tighter curve in the center where it curves right to go into the right hand section. It looks liek there is enough table space to widen things somewhat, but that will require reworkign the scenery. For the curve at the base of the L, just above the control panel, you can add a triangular section of benchwork and move the ends of those curves further left and right to make it a much more gentle curve, the center of the curve then gets stretched across the triangular add-on.

Just for comparison, the full-length Walthers passenger cars will run on a 26" radius but be very tight. On 30" they run great, no issues with the diaphragms or anything. However, two sets cannot pass each other if one curve is 30" and the other 32" = they need at least 2 1/2" center spacing even on curves of over 30" radius.

Upside of the bigger space requirement is that all those locos you mentioned will work perfectly. With 30" radius curves, a 4-8-4 will run even at ludicrous speed without derailing.

–Randy

19

Your Dad did a good job on the layout. I have removed flanges on engines to allow for tight curves by placing them upside down in a home made cradle. Attaching feeder wires to the pilot trucks & running the engine at about 1/2 power…NEVER at full power without a load. Used a 1/2" diameter drum sander in a dremel type tool & carefully trimmed the flange off. finished with a fine file. Be sure to cover all gears, bearings etc with masking tape to keep the grinding dust out. i know you should remove the wheelsets & do this in a lathe, but this will work if you are CAREFUL…jerry