I’m wandering is it a common practice to have an increased grade and then ease
it off a bit once the bench work cross members have been cleared this is for
decending to below bench top elevation to a below table staging area. I have my
staging area descending track going down to a -18.5" level ( its 18.5" below
bench level) decaneding at 2.5 %.
I’m wandering is it practical to start with say a 2.8 - 3.0 % grade so to clear
the bench sooner? Or is a better practice to keep a steady grade all the way
down? I realize that I have to cut away a certain ammount of cross member ends
as it is.
You can see in the pic where I begin in the lower right. If I were to increase
my grade to 3% upto the point where I show the -5".
Will there be any dire effects going from 3% then to a 2.5% ?
The blue outline denotes part of the base for the yrd by the way.
Lynn
Thanks Chip
Staging was very important to me and I still have a long way to go figuring a way to support this staging yard and the supports for going down to it but… one thing at a time [:)]
Lynn
Even the prototypes used steeper grades over a short run, say 300 meters, if it would quickly revert to a much more managable grade, often at overpasses. The key is some momentum at the onset of the steeper part so that the train wouldn’t stall. If the ramp is short, the loco only has to lift what is actually on it, while the rest is on the approach grade and not so burdensome.
If it will do the trick, try it in a carefully measured mock-up first and see how your locos do.
Just be careful not to change the grade too quickly without proper up easings and over easings. Too abrupt could cause uncoupling on longer equipment. Remember that the maximum grade coming out of staging will determine the power needed and train length. A helper district can always be incorporated for this purpose.
Bob K.
Is it better to keep the curves in the decending track at virtually a lesser grade decline\incline and do most of the grade adjustments in the straights ?
Lynn
First … What scale are you modelling ? Knowing that would be helpful for providing more appropriate advice.
Second … Why do you need to descend 18½" ? Do you plan to scenick the staging area ? If not, then you don’t need quite so much head-room. You could probably get away with 6-8" clearance, depending on the scale you’re using (plus the structure of your benchwork).
Third … If I were you, I would descend only a total of about 10" and keep your grade at a constant 2%.
Fourth … The “drag” effect of a grade is enhanced (increased) by adding curves, so you would be wise to keep your grade as shallow as possible.
second -my benchwrok is made from 1x4" framing covered with plywood which is actually of course 3.5"x 3/4" . Yes I suppose I don’t need to go down so far maybe 10" would be fine and I’d still be able to get my hand past the 3.5" perimeter bench framing.
If you look at my staging yard plan the way I have the descendeing track going all the way around beginning from the lower right corner and ending at the staging yard I figured I might as well take advantage of the depth of the staging yard that could be had .
Now I’m not real good with this grade stuff but I figured the farther down I went with staging leveled the quicker I could get the beginning of the descent cleared of the bench
which brings me back to the original question as whether its common practice to start the grade steeper to clear the bench work then decrease to a more gradual grade ?
As mentioned, you need to have a transition (easement) into the grade. A reasonable rule of thumb is to change the grade no more than ¼% per foot of travel. If possible, use a single piece of ¾" plywood for your roadbed from a couple feet before the grade starts to the a couple feet after the grade has reach a constant. This will take care of the transition almost automatically.
You can vary the grade as much as you desire, it is not common practice to do what you describe.
You may want to replace some of your 1 x 4 supports with ones made from ¾" plywood so that you can shape them more effectively - even putting a large hole through rather than just notching them. This will retain the structural integrity of your framework.
