train lenght vs. curves

With our around the cellar layout, we run 90 car freights easily within 4 scale miles.

Wow!

Good for you. Welcome.

What Scale? How many locomotives does it take to pull that many cars? Any grades? What kind of couplers do you use and are the cars weighted to NMRAspecs?

Please refer to this thread http://www.trains.com/community/forum/topic.asp?TOPIC_ID=58584
To answer a few questions. My Dad (Cnvan) and I are currently running 3 trains. 1 Train is a Conrail train, mixed frieght with Intermodal on the end (A caboose too, respectively). We have a Maine Central Freight running, 2 GP-38s and 2 GP7’s with approx. 70 cares. Anymore and we would add mid train. Last train is UP, 2 units approx 50 cars. Regarding grades there are none yet, however we have very wide curves and a reverse curve laid down. All the units mentioned are Atlas and Kato with the exception of one P2k Conrail SD60.

The thing to keep in mind is that there are several factors present. The weight of the cars must all be relatively the same. Lighter cars (flats and gons) should be at the rear. The longer the train, the higher is the safe curve radius. A uniform speed must be held else you will jerk the middle across the curve. NEVER stop the train. Starting up can pull the train across the curve. If I do have to stop, I do as the real railroads, back up and take all the slack out of the couplers so you are starting one car a time, slowly. On my previous layout I successfully pulled 75 40 foot box cars with an ABBA lashup of Varney F units around 30 inch radius curves, on the level. If you keep it moving, all goes well. In my new New Haven layout, I will be pulling 100 car trains from the Hudson River car floats so I am going with a 36 inch minimum radius to be on the safe side. The outermost of the four track mainline will be 42 inch radius, all on the level. Hopefully one EF-4 will be able to handle it.

I occasionally have had a problem with this. Don’t put lighter cars up front, it doesn’t work.