Minimum curve (in degrees) for an E6 when coupled.

[learmoia]

Curious if anyone has documentation for the minimum curve (degrees) for an E-6 when coupled..

What we have says 24 degrees, but does not specify coupled or uncoupled.

Just curious.. ~Ian

[C855B]

Has to be while uncoupled. 24° is very sharp, not unlike most sax players I know (bad music joke - a few here will understand).

[learmoia]

That's what I was thinking, but curves in and out of passenger terminals seemed pretty sharp.. so maybe 24 is correct.

~Ian

[nkalanaga]

Not what you're looking for, but the minimum for a GP-38, coupled to a 50 ft boxcar, is 19 degrees (302 feet), according to the EMD operator's manual.

[Maletrain]

In the book Baltimore and Ohio E-Unit Passenger Locomotives, it gives minimum curve as 21° for all of the E units, starting with the EAs and going through the E9s.  (The box cab AA shows "na".)  It does not state whether that is coupled or uncoupled, but the Es were run as multiple units.

In another place, it gives 274' as the minimum curve radius, which is about 21°.  Since that equates to 20.55" in N scale, that should be doable on model layouts designed for long passenger equipment.

[learmoia]

In the book Baltimore and Ohio E-Unit Passenger Locomotives, it gives minimum curve as 21° for all of the E units, starting with the EAs and going through the E9s.  (The box cab AA shows "na".)  It does not state whether that is coupled or uncoupled, but the Es were run as multiple units.

In another place, it gives 274' as the minimum curve radius, which is about 21°.  Since that equates to 20.55" in N scale, that should be doable on model layouts designed for long passenger equipment.

Cool.. 21 coupled seems reasonable..

There are some tight curves at passenger terminals so it should work..

[Mark5]

In another place, it gives 274' as the minimum curve radius, which is about 21°.  Since that equates to 20.55" in N scale, that should be doable on model layouts designed for long passenger equipment.

This agrees with the E7 manual:

http://www.rr-fallenflags.org/manual/e7-om-2.pdf

[RBrodzinsky]

This agrees with the E7 manual:

http://www.rr-fallenflags.org/manual/e7-om-2.pdf

Interesting, that reference says “maximum curve radius,” although we know it is minimum.

[nkalanaga]

I'll agree that it should be "minimum", but maybe they thought the railroaders would just look at the number, and think "24 is larger than the maximum, so it won't work."?

In astronomy, the brightness of stars is given in "magnitude", which is the same way - the higher the number, the fainter the star.

[RBrodzinsky]

I guess I am not really getting the "minimum curve (in degrees)..." figures.   The restriction is defined by its radius, and not the angle of arc it transcribes.  A loco or car can negotiate a 0.1 degree curve or a 360 degree curve if the radius is greater than its minimum turning radius (ignoring other practical matters).  All the degrees of arc specify is how much the direction of the track changes.

[Maletrain]

I'll agree that it should be "minimum", but maybe they thought the railroaders would just look at the number, and think "24 is larger than the maximum, so it won't work."?

But the manual actually says "Maximum Negotiable Curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 274' radius". 

So, that radius is actually the minimum, and that is what they are talking about.  The 21° curvature (in 100' of track) is equivalent to the 274' radius, but a larger number for the angle of curvature would be a smaller radius. 

So, it looks like somebody with a mind-set for angle of curvature wrote something about radius of the curve.

[Maletrain]

Rick,

When railroads talk about curvature in degrees, they mean the change in direction of the track over 100' of travel.  Maybe sometimes they actually lay it out as change in angle to a point that is 100' away in a straight line, rather than following the path of the rails.  For realistic curves, the difference is small.  There are formulas for both to convert them to radius of a curve. 

[RBrodzinsky]

Rick,

When railroads talk about curvature in degrees, they mean the change in direction of the track over 100' of travel.  Maybe sometimes they actually lay it out as change in angle to a point that is 100' away in a straight line, rather than following the path of the rails.  For realistic curves, the difference is small.  There are formulas for both to convert them to radius of a curve.

Thanks!  I never understood that detail, makes sense, now.

[nkalanaga]

Maletrain:  yes, maximum radius in feet makes no sense whatsoever.  Maybe the trucks are stuck and it won't run on straight track?

And, yes, they do lay out curves by angle, using a chain, and offsetting from a straight "tangent" line by a certain amount.  Surveyors always do it that way, at least for any reasonable curve, simply because it's usually not possible to measure the radius.  Try swinging a 500 ft tape measure when there's a mountain, or a lake, or a building, in the center of the curve.

Also, it makes easements much easier.  Start with a very small offset, and offset a little more with each "chain", until you get to the radius you want, then offset the same angle for each chain.  At the end of the curve, do the opposite.  Railroad curves, at least in the US, are very seldom simple circular curves.  A good track diagram shows the degree of curvature for each "chain", but such detailed maps are seldom published.