15 inch curves

[wally]

Will a 4-4-0 handle a 15 inch radius curve? Is there any steam engine that will handle that small a radius?

[ABC]

I searched several sites for the American and Richmond (Spectrum) versions of the 4-4-0, and the minimum radius for both is 18 inches. (Source modeltrainstuff.com).
The 2-8-0 consolidation also has a minimum radius of 18 inches.
The 3 truck shay has a minimum radius of 18 inches.
The 0-6-0, 2-6-0, 2-6-2 & 4-6-0 all have an 18 inch minimum radius.
Of these listed above the 0-6-0 and the shay would probably do the best on the 15" radius, just make sure to have really good trackwork and keep all rolling stock below 40 feet in length.
A locomotive that would not have any trouble with 15" radius would be either an 0-4-0 shifter or tank engine, but unfortunately Bachmann does not make an 0-4-0. But Model power does among others.

[OldTimer]

It would depend on the size of the 4-4-0.  The old Mantua General would negotiate a 15" radius curve and I expect that the Rivarossi/Pocher 4-4-0's would also get around a 15" radius curve without any trouble.  The new Bachmann 4-4-0 is a much larger engine and I'd be leery of extremely sharp curves.  I know that virtually any 0-4-0 will do fine and most 0-6-0's should be okay--just watch for sufficient space between the loco and tender.  You didn't ask, but 40' cars should be okay, although coupler gather might be a problem.  

[wally]

Thanks for the information. Wally

[Johnson Bar Jeff]

It would depend on the size of the 4-4-0.  The old Mantua General would negotiate a 15" radius curve and I expect that the Rivarossi/Pocher 4-4-0's would also get around a 15" radius curve without any trouble.  The new Bachmann 4-4-0 is a much larger engine and I'd be leery of extremely sharp curves.  I know that virtually any 0-4-0 will do fine and most 0-6-0's should be okay--just watch for sufficient space between the loco and tender.  You didn't ask, but 40' cars should be okay, although coupler gather might be a problem.  

The Rivarossi/Pocher/IHC 4-4-0s will indeed negotiate a 15"-radius curve, though with a good amount of "pilot overhang." I know this from experience. the Mantua/Tyco "General" also has no problem with a 15" curve.

I can't speak about the Bachmann "Jupiter" or "U.P. #119," but being small engines, I presume they would also do OK on a 15"-radius curve.

[ABC]

I can't speak about the Bachmann "Jupiter" or "U.P. #119," but being small engines, I presume they would also do OK on a 15"-radius curve.

There was a Bachmann 4-4-0 down at my local club, I borrowed it to see how it ran, the lead trucks will give you a lot of trouble on 15" radius.

[Jim Banner]

To answer the second half of your question, 0-4-0's will handle curves down to about 9", depending on brand.  The prototype 0-4-0 were originally meant for switching in tight quarters such as streets, alleys and docks.  That is why many 0-4-0's are referred to as "docksiders."

Because they have only 4 pickup wheels, 0-4-0's demand clean rails, clean wheels and turnouts with powered frogs.  If one of these little fellows does not provide enough power, you can always couple two or more together.

If you want to talk diesels, a great number of 4 axle diesels work just fine on 15" radius curves.  The road units may look at bit odd on curves that tight, but switchers look okay.  I hear Bachmann 44 and 45 tonner center cab diesels will run well down to at least 12" radius.

Jim

[ABC]

I hear Bachmann 44 and 45 tonner center cab diesels will run well down to at least 12" radius.

Yeah, they can both make 9" radius according to someone at my club. I have not run my 45 tonner on anything smaller than 15".

[Johnson Bar Jeff]

I can't speak about the Bachmann "Jupiter" or "U.P. #119," but being small engines, I presume they would also do OK on a 15"-radius curve.

There was a Bachmann 4-4-0 down at my local club, I borrowed it to see how it ran, the lead trucks will give you a lot of trouble on 15" radius.

That really surprises me. Not enough room for the pilot truck to swing?

[Jim Banner]

I believe the problem with 4-4-0's is that the rear wheels do not swivel like the front ones do.  The front ones are much like a diesel truck and can swivel as a set.  The rear wheels are rigidly attached to the frame, at least as far as swiveling is concerned.  If the rear wheels are in a curve, they try to swing the front of the locomotive the same way - if the curve is to the left, the front of the locomotive swings to the left.  If this puts the king pin of the front truck over the center line of the track, there is no problem.  But if it puts the king pin to one side of center, the swing will put lots of side pressure on the wheels and off the track they come.  The problem is exacerbated by the distance between the rear wheels and the front wheels and is particularly bad in S-curves.

If you compare a 4-4-0 to something like a Pacific (4-6-2) which also has a 4 wheel pony truck, you will notice two things - the king pin on the Pacific is closer to the front drive axle than on the 4-4-0 and the front truck of the Pacific has some method of allowing side swing in addition to the rotation of the truck whereas the 4-4-0 does not.  While 4-4-0's in the real world can rock and roll down some really rough track, they cannot handle the extremely tight curve that a 15" radius represents.  Because of the side to side motion built into its leading truck, a model Pacific is more likely to handle 15" curves than a 4-4-0.

If you want something other than a docksider (0-4-0,) consider a Porter (2-4-0,) a Columbia (2-4-2, which you can make from a 2-4-0 or an 0-4-0,) or possibly a Jubilee (4-4-4.)

Jim

 

[ABC]

That really surprises me. Not enough room for the pilot truck to swing?

It may be of interest that Bachmann lists the minimum radius for the standard and Spectrum 4-4-0s at 18 inches in the online PDF catalog.

[mf5117]

I know I posted about this before . will a gp-35 with 40ft pulp wood cars handle the 15" rad. ...I haven't bought any 15" rad track yet was looking at it for the starting curve of my incline . 2 gp-35' 4 or 5 40ft pulp wood cars      HO

[Doneldon]

The Geep and 40 footers will probably handle the radius but just barely.  I'm concerned that you may be adding to your operational woes by including a grade with the very tight curves, especially if the grade and curves start at the same point.  At least start one before the other.  Moreover, I strongliy urge you to reconsider this plan.  In fact, I urge you to everything you can to get away from the 15" curves altogether unless you are modeling an early mining or timber road.

[ABC]

Bachmann says to use at least 18" radius for a GP-35. But the 40 foot wood pulp cars will make it, but the GP-35 will derail due to the extreme curves and the elevation changes like Doneldon said.

[mf5117]

Im using 2 gp-40's now with 18 radius curves , at the start of my grade incline.  And they pull the load up and down just fine .I have 2 gp-35's I was hoping maybe I could use due to the smaller engine , And 15" rad curves due to space but I think I will leave what I have . More and more space is an issue , and my trains are just sitting .