min. radius for steam 2-8-2, 4-8-4, etc

[NYSW F45]

what is the minimum radius for most steam engines? looking at a 2-8-2, 4-8-4 or something along those lines. Saw the IHC makes quiet a few in the wheel combo's im thinking off. How is the quality of the IHC steamers? Do any come with sound or have an option of putting sound in them?

 

[UP2CSX]

Minimum radius for reliable operation for a small to medium size non-articulated locomotive is 22". 26" or bigger would make them look better.

IHC has made everything from junk to some really nice steam locomotives. I'd have to know an exact model to tell you what class it falls in. I'm not aware of any IHC steamers that come with sound. It's possible to put sound in almost any locomotive. It's just a matter of money, skill, and available space. If I was in the market for a steam locomotive, I'd check the Bachmann Spectrum offerings before buying anything from IHC.

 

[NYSW F45]

UP, the IHC one i saw at the hobby shop on sunday was the 2-8-2 Mikado. Walthers lists it under "premium series steam loco's." The 2-10-2 is listed under that one too. Both of those are the only ones that come undecorated. Reason i was looking at the undecorated was I could put the new road name for my layout on it once I have decals printed for it.

 

[Cjcrescent]

If you're still looking at the IHCs, they build their mechs just like many of the less expensive steam models built in Europe. That is, enough "slop" is built into the mechanisms to allow even the articulateds to go around an 18" radius curve.

However, as we say here in the south, jes' cuz ya can, don't mean ya shud!

Locos that size just don't look "right" running on such tight radii.

 

[UP2CSX]

Both of those IHC locomotives are nice but make sure they say "DCC Ready". Some of the so-called "Premier" series are not and fitting DCC is a real pain. See if you can find a Bachmann Spectrum model and compare it to the IHC models. While IHC has improved considerably, the Bachmann Spectrum line of steam lcomotives still have better detail and are better runners. The 4-6-0 would be much better suited to 18" radius curves than the larger models. You can get most models in black undecorated and many come with DCC already installed. They are a little more money but, if you have the budget, I think they are worth it. In addition, Bachmann has lifetime warranty on all their locomotives. If anything ever goes wrong, you send it back along with $15 and they either fix it or give you a new model.

 

[HaggisKennedy]

The older Premiere series, in the purple boxes, don't have any kind of DCC plug or stuff like that, so if you convert, it's a hard wire. Though I've been told that it's rediculously easy to do so. Can't say, since I've not done one. But, once you get it apart, there's only a minimal number of wires. There's a couple of sites that talk about converting IHC locos, Allan Gartner's, for one.

The new 2-10-2 has a plug inside already, and should be easy to find a suitable decoder. I think it's the 8-pin plug (but I can't recall). I have one of these in the Marination Station.

I also note that IHC has come out with a couple other locos that have the DCC plug in the tender. These are also the 2-8-2 and 4-6-2.

Kennedy

 

[Tuna]

All Steam

I have an IHC 4-8-2 that handles 18" radii just fine but my Genesis 4-8-4 doesn't like them at all.

The minimum radius required is a function of how long the rigid part of the frame is and the number of wheels on that frame.

That depends on how big the drivers are. The bigger the drivers, the longer the frame has to be and the more length between the first pair of drivers and the last pair.

My IHC 4-8-2 is patterned after 70" drivers while my 4-8-4 is patterned after 80" drivers.

I also run articulated locomotives and have a Spectrum 2-6-6-2 Mallet Mogul, a Genesis 4-6-6-4 Challenger and a Genesis 4-8-8-4 Big Boy. The Mallet Mogul is based on 56" drivers and handles 18" radii just fine while neither of the Genesis locomotives dislikes 18" as they are based on 70" and 68" drivers.

Some of this depends on how much left-to-right slack is built into the frame to allow the drivers to 'follow' the curve.

 

[Tuna]

Steam Wheelbase controls

Howdy,

This post got me to thinking about the actual 'wheelbase' on my steam locomotives and how that effects the minimum track radius. So, I measured mine to see what they are. I measured first driver axle centerline to last driver axle centerline for each set of drivers on a single frame. The bigger the wheelbase, the bigger minimum radius required.

Genesis 4-8-4 UP 844, recommended min = 22, wheelbase is 3 1/8 inches
Genesis 4-8-8-4 UP 4024, rec = 22, wheelbase is 2 1/2 inches
Genesis 4-6-6-4 UP 3958, rec = 22 but say 18 is doable, wheelbase is 1 3/4
Rivarossi 4-8-4 UP 844, none, wheelbase = 3 1/8 inches
Spectrum 2-6-6-2 W&LE, rec 18, wheelbase is 1 1/2
IHC 4-8-2, rec 18, wheelbase is 2 5/8 inches

So, it appears that around 2.5 inches of wheelbase would be the magic number for switching to 22" radius turns but it is not always true as my IHC 4-8-2 is more than that but works okay on 18". The IHC has more side to side movement in the axles while the Genesis locomotives do not have very much.

I can't imagine how big the minimum radius would be for an HO scale version of UP 4-12-2! One of the reasons why UP bought 4-6-6-4's since articulated locomotives can handle smaller radius turns compared to the same number of drive wheels on a single frame loco.

 

[HaggisKennedy]

There's always been an interesting discussion regarding articulateds and what min radius they will go through. Overhang aside, most articulateds pivot on both engines, so you get the ability to go throught smaller radiuses than would be prototypical.

Though if you think about it, even if the rear engine was fixed, you're still talking about a X-8-2/4. Anything in front of the '8' could be considered a pilot (it does pivot), and thus if the rear can go through an 18" curve, then the front should also (presuming both are equally in scale). I say that because the 2/4-8-x is a mirror of the back half.

Of course, the boiler is one huge-o rigid item, and it'll look weird, but that's a different issue.

My P2K 2-8-8-2 will go through the min radiuses OK, and it looks a bit odd, but is acceptable to me. But, my Rivo cab-forward really looks out of place; just doesn't look right, but it will take that min radius without derailing.

Kennedy

 

[Boilerbuster]

I am running all mine on 15 inch radius at the moment without any problems. Up to a Southern pacific GS4 4-8-4.

 

[TWhite]

Most of the modern HO articulateds are double-articulated and will take much smaller curves than, say, a brass articulated, in which only the first set of drivers swivel, and the second set, under the firebox is rigid, which is how the prototype loco's were built.

Be that as it may, even rigid-frame articulateds seem to be able to take smaller radii than, say, a 4-8-4 or a 2-10-4. Although I know that some of the newer plastic locos are rated at 18" or above, I'd be leery of using a 4-8-4 or a 2-10-2 or 2-10-4 on anything under a 22", and would feel much safer with at least a 24" radius.

Most of my HO steam is brass, which means that they are largely built to tighter tolerances, and so my curves are much more generous--34" to 36" radius. Even at that, I have several brass 2-10-2's that squeal through the 34" radius, whereas my brass articulateds (2-8-8-2, 2-8-8-4, 4-6-6-4) glide through them with absolutely no problem. In fact, my older brass Yellowstones cut their teeth on a 24" radius when I was starting out, some years ago.

But I've heard of current plastic rigid-based steamers such as 4-8-4's and 2-10-2's negotiating 18 to 22" radius with absolutely no problems.

Seems to depend pretty much on what you're looking at as far as 'big' steam motive power.

Tom

Tom

 

[Boilerbuster]

My 4-8-2 PRR M1A which is the new blue line Broadway limitied engine is build for tighter turns. The middle two drivers are flat and have no flange on them. only the front and rear drivers have that flange alowing the locomotive the abilitie to make turns of less then 22 inch. Of course for some time i and still do have a few problems with derailments of a few of my enignes. They require a break in time and when I get a new one I run it for a day on a small loop to make sure they will run without problems. I cant however run my passenger cars which are to long. When I start my layout I am going to fix this with a larger radius turn and may stick to turns of above 30 inches I plan to only use my Larger engines for mainline service anyway. I do have smaller engines for switching and other tight work.