[GlacierBill]

This may be a questions that was already answered but I can not find it, I have a Bachmann set and was wondering what is the max grade one can get up, I have seen several photos of trains climbing 8" (or enough for a train to clear the bridge) in what looks like about 8', is this reasonable. What are the deciding factors? I am planning on pubbing from 4 to 6 cars? Any ideas?


 

 

[East Broad Top]

Grade is measured in terms of rise over run, expressed as a percentage. A rise of 8" over a run of 8' (96") is roughly an 8% grade--8" rise over (almost) 100" run. That's about twice as steep as what is considered the maximum advisable grade for model railroads. If you can stretch that to 16' of track to rise up 8", then you'll be at a 4% grade. I recommend trying not to exceed 3% if at all possible. A train of only 4 to 6 cars with the average loco will not have any trouble on a 3 or 4% grade. But that's not necessarily an invite to pull steeper grades. There are internal forces in the gearing of our locos that tend to cause issues on steep grades regardless of how many cars the loco's pulling.

Later,

K

 

[altterrain]

Yeah, what Kevin said. Actually this is just a test post!


-Brian

 

[Guest]

Very Sound advice from the Kev...I have some grades and it does affect the running more than one would expect.  I am planning on reworking my steepest part this winter.  i model NG Steam-in the mountains, so some grades work for me, it is pretty cool to have the loco running along the flat, the hitting the grade and the sound change...it can sound like it is really "Working"...just like a 1:1.


 


cale


 

 

[imrnjr]

I have a 5.5% grade on my railway that the Bachmann BH's can get up with tender and 3 cars, but they struggle just like a real engine would.   in another area there is a 2.5% run that they have no proble with pulling up to 8 cars and the tender, I have not had a stripped or split gear yet, but expect it will happen sometime./DesktopModules/NTForums/themes/mls/emoticons/blush.gif  If you can manage it keep the grades under 3%.


 


Mark

 

[slimgauge]

Also remember that the percent grade is generally for a straight grade (no curves). If the grade includes a curve, the effective grade is greater due to flange resistance. When you hear the term "compensated grade", it means the grade has been adjusted to compensate for this added resistance. According to one source, in the prototype, the compensation is 0.04 percent grade per degree of curvature. I have no idea how that works out in model terms.

 

[up9018]

On the railroad I'm planning I also have a very large climb to make in a short distance....so I'm designing in the old Colorado trick.....The Georgetown Loop.....this gets me the length i need to make the climb in the area i have available to do it....plus it will be just cool looking!

 

[weaverc]

Grade is critical if you plan to run live steam. Some live steamers climb and descend better than others, like the Shay and other geared locos for example. One way to help a live steam loco with grades is to install radio control on the steam valve (throttle). Just a note for you if a live steamer is in your future.

 

[stanman]

On the Swiss RhB, the Bernina line has a maximum grade of 7%, and you can really feel that the powerful electric locos are struggling. The maximum grade of the other RhB lines is 4.5%.


I've been on the MGB (Matterhorn Gotthard Bahn) between Brig and Zermatt. The grade on this line is as high as 11%, which requires a cogwheel drive loco. (The MGB was formed by the merger of the BVZ and FO.)

 

[Great Western]

On one side of my railroad I have a large, but very beautiful when in flower, magnolia tree.   As the ROW passes near to its trunk I have, of necessity, had to have small grades either side of the tree. The initial construction meant that the approach from the south was the lesser of the two grades and I always ran the longer consists (up to 10 wagons plus caboose) in that direction. Late last summer I managed a re-alignment of the northern approach which now means that the smaller grade is now on that side of the tree allowing running longer consists in either direction.
In the spring I plan to lessen the southerly grade by lengthening the distance from its base to the top of the grade. This can be easily achieved by raising the ballast Hopefully this will mean less effort on the locos part. This MOW work should be quickly achieved as this section is single track and the curves are 8ft. and 10ft. dia.trackwork.

The Georgetown Loop sounds a great option but sadly I don't have the space for that.

 

[aceinspp]

If feasable keep the grade to a minimum and you will be a lot happier.  Later RJD

 

[work4fil]

If you went to an after market drive, like Barry's Big Trains, would the impact of an adverse grade (5% or greater) be softened?  I have watched Mark's railroad with interest for some time.  In reading his post, it sounds like he may have an issue down the road.  If a gear failure is inevitable, is spending money on an after makrket drive worth it?

 

[Al McEvoy]

Slimgauge, you bring up an interesting topic, and despite my following explanation I'm sure that in our world of model trains, it isn't quite as critical as the prototype.  But here goes since you baited me.


To be able to calculate degree of curvature and then translate to radius (or actually vicve versa), you first have to decide what scale you are using.  If we're talking Bachmann Big Haulers, aren't they about 1:22.5 scale?   One degree of curvature in standard American gauge (4'-8.5") is achieved by using a radius of 5,729.65 feet. I have provided a reference URL for those interested in where that number came from.  In 1:22.5 scale, the radius needed for 1 degree of curvature would be 5729.65 divided by 22.5 or 254.65 feet.  More practically, if you are using 10 foot diameter curves (5 ft radius), in this scale you are representing 5 x 22.5 or 112.5 foot radius curves which equates to approximately 51 degrees of curvature (really really sharp curves).


That would mean that if you use 10 foot diameter curves on a grade, you would want to reduce the grade 51 x .04 or approviamtely 2% on the curved portions.  So if you had a 3% grade, you would need to drop back to a 1% grade in the curved portion. Not always easy to do.  By the same calculations, those engineers using 20 ft diameter track (Aristo's widest sectional track) are representing a 25 degree curve, so they would need to reduce grade by .04 x 25 or about 1.0 %  in the curves.


You can see that this can easily become quite impractical in the space we have for our pikes so we compromise. In the end, we need to keep grades minimal in curved sections, but I don't think all this "compensated grade" calculation is required for 98% of our layouts. In the real world it's all done for proper engine loading and to try and minimize forces that would overcome dynamics and traction.  But it's helpful to understand what would be ideal from an engineering perspective.


PLUS, the transition from one grade % to another % needs to be gradual. There is even more complex math to calculate the "vertical curve" required for the transition gradient, whether peaked (convex) or valleyed (concave).  I would just make sure it's gradual enough to clear all cowcatchers, keep all engine wheels on the track, and not cause couplers to unhook. /DesktopModules/NTForums/themes/mls/emoticons/satisfied.gif  I thkk most folks just try to maintain a steady gradient an not have an undulating track on any grade.


Reference: http://mysite.du.edu/~jcalvert/railway/degcurv.htm


AL