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Superelevated Curves, Wheel Drag Track and electrical/DCC
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Prolific poster 1,723 posts musgrovejb Prolific poster 1,723 posts
musgrovejb

On my HO switching layout I have 24-Inch radius "super elevated" curves using plastic shims underneath the ties.  All curves have proper easements.  

The super elevation height change is very gradual, (at least slightly longer than my longest 60-foot car), and set at the following levels throughout the turn:

.010 - before the start of the curve and into the begging of the curve

.020 - next level up 

.030 - maximum elevation

The super elevation of the curve than decreases from .030 to .020 to .010  

Noticed a "slight drag" when cars move through the curves.  The drag on some cars may be slightly worse than others depending on the length and type of flange. 

Used a 24 inch radius track gauge when aligning the curves and cannot spot any problems such as kinks or sharp bends.

Is this drag normal with model railroad super-elevated curves, similar to the actual prototype, or am I looking at another issue here?

 

Modeling Missouri Pacific Railroad's Central Division, Fort Smith, Arkansas

https://youtube.com/playlist?list=PLENIMVXBDQCrKbhMvsed6kBC8p40GwtxQ

 
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ctxmf74 Super User 15,952 posts
ctxmf74

"a "slight drag" when cars move through the curves"

  24 inch curves are pretty sharp for 60 foot cars. Did you do a test on non-superelevated track to see if there is any difference?  I wouldn't super elevate a switching layout as it is not needed at low speeds ...DaveB

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duckdogger Super User 808 posts
duckdogger

Broad curves

I installed 59-inch super elevated curves on the store's railroad and do not notice any increased drag. We are running 25 foot long freight trains and 11 car passenger trains. The only difference I note is the Walthers passenger cars roll more easily than those from BLI but that is not a function of the elevated curves.
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robertw144 Regular poster 232 posts
robertw144

Where do you start the superelevation?

Do you start the superelevation right where the curve starts then gradually raise the height of the outer rail, or do you begin the superelevation in the tangent of the curve?

Robert Gross
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IrishRover Prolific poster 1,660 posts
IrishRover

Superelevation on switching layout?

Is super elevation even used on low speed track?  It seems to me that there would be very little lateral force at switching speeds.
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Selector Regular poster 427 posts
Selector

Super-elevation is used

Super-elevation is used whenever the engineers think it will be necessary, but that virtually never takes place in yards where only low-speed travel is authorized.  Recall, though, that often yards extend well beyond what their apparent physical limits would suggest...with the governing speeds assigned commensurately.

There is video available showing lumbering Y Class Mallets slowly shoving long heavy strings of 70 ton hoppers along the curved twin main lines crossing the Blue Ridge back in the late 40's.  The rails are heavily canted with super-elevation, making the slow Mallets look dangerously tilted at such slow speeds.  Yet, on the tracks beside them, a fast moving A Class roars past at 60 mph taking a string of empties back to the loading facility, also heavily canted.

You will see super-elevation anywhere a train is expected to maintain a schedule at speeds other than yard limit speeds.  That means on spurs as well as on a main line where truly high speeds are likely to be required, particularly by time-sensitive freights and passengers.  I don't know what the speed will be at any one point, but it depends on the other factor of degree of curvature and what in the cars riding on those rails can withstand in the way of lateral forces safely.
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duckdogger Super User 808 posts
duckdogger

Elevation transition

Regarding where do the spacers begin, I start at the transition from tangent to curve. I personally only use them on mainline curves where there would logically be faster speed limits.
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David Husman dave1905 MRH Author 9,846 posts
David Husman dave1905

3" (scale) superelevation? 

3" (scale) superelevation?  Your trains must be operating at 45-50 mph around those curves.

The drag probably doesn't have anything to do with the superelevation and more to do with a sharper curve.  The sharper the curve the more the flanges rub on the head of the rail and the more one wheel or the other has to skid on the curve.

Just as a comparison on my 45 mph tops, 27" curve I use 3 layers of masking tape as the max superelevation.

Dave Husman

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