Looking for feedback from owners of Rivarossi Allegheny steam locos.
What are the minimum radius curves you have been able to operate on without derailments?
Brian,
I can’t offer any specific answers to your question, I have an Allegheny, but as you know my curves are big…
But, I will share another basic principal of railroad physics often missed about steam locos and curves.
The most important factor for steam locos and curves is the rigid wheel base of the drivers. This controls minimum radius more than any other factor.
So, for example, the Allegheny has a very short rigid driver wheel base for such a large loco, only 11.83’ for each three axle set. This makes the loco very nimble for its size. Especially considering the double swivel design of the model.
The Allegheny will work better and look better on any given curve than, for example, the C&O 4-8-2. Why?, because the Mountain has a rigid driver wheel base of 18.25’.
Here on the ATLANTIC CENTRAL, even with 36" radius curves, I limit steam loco rigid wheel bases to 21’, with a few USRA 2-10-2 lights being the longest rigid wheel base.
Examples of locos prohibited due to length:
SP GS4 4-8-4 - 21.5’ rigid wheel base
B&O S1 2-10-2 - 22.30’ rigid wheel base
Here is an example of how driver diameter effects rigid driver wheel base:
USRA 2-8-8-2, 57" drivers, 15.5’ rigid wheel base
Compared to that GS4 above, 80" drivers, 21.5’ rigid wgheel base
Eastern prototypes tended to have smaller drivers and were more suited to sharper curves.
A story from the prototype: The B&O has two main routes west, one directly west from Baltimore to Cincinnati, it is very curvy, and has many up and down grades. The primary large steam on this line were the 2-8-8-0’s and the EM-1 2-8-8-4’s, rigid wheelbase, 16.50’. Longest locos commonly used on that run, T-3 Mountains, 18.25’ driver wheel base.
The other goes north thru Pittsburg to Chicago, it has longer, straighter, fewer (but just as steep) grades, and much broader curves. The pr
Hi there. There is a MR review dated 2002 that says that the manufacturer recommends 24". The reviewer states that it can handle 22". I have a Rivarossi Big Boy and a Mallet and they can handle these no problem. Of course, this assumes that all other factors are in check, such as good track, no s curves, etc…
Simon
You also need to consider boiler swing (and cab swing if the pivots are both in the center). Keep an eye out for obstructions the loco can strike in these areas, run back and forth before placing buildings, bridges near curves, curves near walls, etc.
Wouldn’t that be covered by some of these clearances needed for steam locos,
http://cs.trains.com/mrr/f/88/t/267707.aspx?page=4
You can see that the rear cab of this Allegheny loco sticks out fully to the mid point between these two tracks. That track spacing is 2+1/2" between CL’s. Thus this loco requires a minimum of 1+1/4" clearance at its outer side on this 28.5" curve.
Note that another Allegheny, or one of the longer freight cars, could be traveling on that outer track and still NOT interfere with this inner Allegheny.
I was listing some things that would cause issues, I have not been following the other thread.