I get asked this question from various bases from time to time, and while I can make an educated guess based on problems we've had in the past, I've not found an authoritative source I can refer people too.

I have a relatively recent Car & Locomotive Cyclopedia and while it lists lots of data for most cars out there, nowhere does it list minimum curve data.

Can anyone refer me to a better reference?

Greg

Hello Greg,

I don't know exactly what type of car you are referring to, but I will assume it might be an 89' flatcar.

The minimum curvature can vary depending on whether the car is coupled, or uncoupled as it negotiates a curve.

I've provided this link below to Greenbrier International's website. As you may be aware, they manufacture 89' flatcars.

https://www.gbrx.com/manufacturing/nort ... 9-flatcar/

According to the specifications listed on above webpage, the minimum radius curvature appears to be 350' (when coupled to either a base car, or a "like" car). The needed radius is considerably less if the car negotiates the curve "uncoupled".

Hope that answers your question.

That would be about a 16 1/2 degree curve.

Steve

The minimum curve would vary with the distance of the truck centers from the ends, no? Does that ever vary?

It sure does. It depends on the type of car and the type of draft gear.

Which begs the question of how it gets around any curve without being coupled to something, whether a locomotive or another car. Or do you just kick it and cut it loose and ride the handbrake?

[quote="Lincoln Penn

Which begs the question of how it gets around any curve without being coupled to something, whether a locomotive or another car. Or do you just kick it and cut it loose and ride the handbrake?[/quote]

In the Naval Shipyards where we have a LOT of really tight curves, we move some cars around tight curves individually with locomotives equipped with couplers that can slide laterally across the locomotive to accommodate the offset. Alternatively, you can use a rubber tired tractor equipped with a coupler.

Greg

Puget Sound Naval Shipyard has that problem as well. They also have what is most likely the newest 40 foot flatcar on the planet. Brand new, very heavy duty, but really short to go around the tight radius. They could possibly be 50', but they sure look like 40's!

Minimu radius may also be limited by the maximum truck swing (rotation) before something starts to bind.

Passenger car disk brake disks have been damaged beyond repair by chafing (chewing into is a better description) against carbody center sills on way-too-tight shipyard access track curves designed to barely accommodate 40' boxcars coupled together.

- Doug Debs