Minimum curve radius on US branch lines & at customers

T

.Taurus.

New member
Hi
Title says everything!

What's the minimum curve radius, through which US 2-axle-truck engines fit?
In my fictional but prototypical layout i went down to 100 m / 300 ft

The (fixed! not swinging!) couplers of the railcars have more or less contact to theirs counterparts, but can the cars itself go through these tight curve in real ?
And how fast? 10mph ?

Bye
 
minimum US curve radius

Hello Taurus,

The best contemporary practice is a curve no sharper than 12 degrees, about 146 meters, but a contemporary railroad would use such a curve only if there is no alternative. The sharper the curve, the greater the wear and stress on the roadbed and equipment, which translates into money spent on maintenance.

You can find the minimum turning radius of various types of diesel locos on line at The Diesel Shop, http://www.thedieselshop.us/INDEXBLDR.html. This site has specifications, including minimum curvature, on models from the middle of the last century to date. Typically, these minimum curves run about 60 to 90 meters, if memory serves me. Some locomotives were designed to go around extremely sharp curves. I just looked up the EMD SW9, a locomotive designed especially for switching (shunting, I guess, in European parlance), and it was designed to negotiate 39 degree curves, about 45 meters in radius. But this is just the sharpest curve the locomotive alone could negotiate without suffering damage or throwing a tantrum and jumping onto the ties.

The real limiter is the couplings. In close built up areas there might be curves quite a bit sharper than 12 degrees, but special precautions would be taken when negotiating them. In some cases, cars would be uncoupled and pulled around such curves with chains. Special motive power might also be employed, such as the Pennsylvania RR's fleet of rubber tired tractors that rode on city streets while pushing and shoving boxcars to their cramped destinations. Obviously, the speed limits would be very low, probably lower than 10 mph.

Basically, if there is a profit in it, railroads will find to a way to get their equipment in position to earn it, so just about anything that does not defy the laws of physics is permissible. In fact, there is a school of thought that every model railroad should have one bizarre thing, but no more than one, for interest.

Happy hunting for info. The whole subject of railroad ingenuity is fascinating.

Bernie

PS: Several US railroads have sites that set out their specifications for curvature and track construction and geometry designed for customers constructing privately owned trackage for use by the railroad in serving them. You might try Reading Northern and the Union Pacific sites to start.
 
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The B&O had some 100ft (30m) radius track on there docks witch is why there famous 0-4-0 docksider was made.
 
.Taurus. said:
What's the minimum curve radius, through which US 2-axle-truck engines fit?

The (fixed! not swinging!) couplers of the railcars have more or less contact to theirs counterparts, but can the cars itself go through these tight curve in real ?

And how fast? 10mph ?
Click to expand...

The minimum radius is going to depend upon the distance between the trucks / bogeys, and the distance between the wheelsets in the bogeys. ANd typically there will be two different figures, as the locomotive can go through a tighter curve uncoupled than it can coupled to a car.

If you're not already aware, the manufacturers of real rail cars have websites, and in many cases have specifications on the sites of their current offerings, said specifications usually including information on the radius the car (and locomotive) can traverse alone, and coupled.

As to speed, on minimum radius curvature it's not going to be as fast as 10 miles per hour; more like 3 or 4. At ten mile an hour, the wheels are going to tend to climb the rail, and derail the truck, even on good track, and industrial trackage is not often going to be considered "good".

ns
 
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