Thanks for the reply . . . nothing special in terms of power, just an
average Hornby or similar and 4 - 5 passenger cars or 10 - 15 goods
wagons
thanks
8 feet length on a 4 inch rise will give you about a 2 percent grade,
which would be my recommendation. The formula you use to determine the
percent of grade is: one quarter inch rise for every 1 foot of length
equals about 1 percent grade.
Fred Ellis
At a grade of 1%, that would be 100*100mm or 10,000mm [1,000cm, 10m]
(or 100*4in or 400 inches [33-1/3 feet]). 1% is fairly slight. At 2%,
it would be 50*100mm or 5,000mm [500cm, 5m] (or 50*4in or 200 inches
[16-2/3 feet]). 2% is beginning to get 'steep' for many locos pulling
trains of non-trivial size. Note: grades are effectively *worse* on
curves: a grade on a curve 'behaves' (in terms on traction / power
needed) as if it was steeper than the same grade on a straight section,
so the grade on a spiral would have to be more gentle. A 36" radius
circle has a circumfrence of 226.19448", so once around at 1% is a rise
of 2.2619". This is *barely* enough to 'stack' trackage (unless you are
running double stacks or Superliners (double deck passenger cars)).
Separating 1/2 circles by 4' inproves things:
1st 1/2 circle (36" radius) @ 1%: 1.1309" rise
1st 4' straight @ 2%: 0.9600" rise (2.0909" cumulative)
2nd 1/2 circle (36" radius) @ 1%: 1.1309" rise (3.2218" cumulative)
2nd 4' straight @ 2%: 0.9600" rise (4.1818" cumulative)
4% Grade (way to steep) takes 8ft to get 4in height.
3% Grade (most commercial pier sets in HO) take 12ft to get 4.5in
height.
2% Grade (max generally recommended) takes 16ft for 4in height.
Len
: Can anyone suggest the minimum length required to meet a rise of 100mm
: or 4 inches in HO scale.
:
: Any help is greatly appreciated.
Don't forget to allow for the vertical transition curves at the beginning
and end of the grade. Take a look at:
formatting link
Unless you're doing mountain, logging, or old time railroading, a 2%
grade is aout as high as you should go to stay realistic. That would
take 200 inches or a little over 16 feet, plus a little extra for
transition curves.
Wolf, thanks for the correction. I thought I had made a miscalculation.
I should of wrote "16 feet of length on a 4 inch rise will give you
about a 2 percent grade."
Fred Ellis
Depends on the sort of railroad you want to model and how much space
you have to model it.
Major prototype roads try very hard to hold their grades to less than
2% (that would be a two-foot rise for every hundered feet the rails
cover horizontally) as it starts getting very expensive in terms of
the number of locomotives required to pull a given load -and the fuel
they must burn to do so as the grades get steeper and steeper. But in
a modelling situation we rarely have enough space to climb to the
heights we need unless we use 2% or more. (We are fortunate in the
fact that most model railroads are quite short in terms of scale
milage, and as a result they do not generally allow us to run
prototype length trains anyway.) And the requirement that we *must*
pull shorter trains also means that we can run them up grades that
would be steeper than those that generally occur in real life. (If,
OTOH, you are modeling a mining or logging line, it wasn't unusual to
see them use 4% grades or higher, and even 7% or steeper wasn't
unheard of.)
While the currently accepted ideal for model railroad grades hovers
around 2%, you should know that many classic model railroads have been
built using 4%+ grades, and that they were built that way on purpose.
John Allen's famed Gorre & Daphetid railroad used 4% ruling grades
simply because the heavy grades allowed him to pack a lot of mountain
railroading into a relatively small basement with track running from
29" above the floor all the way up to 60" at the highest point: a
climb of over 2 1/2 feet!
John favored short (six to fifteen car) trains on steep grades anyway,
because they allowed him to do some interesting prototype moves such
as double-heading steam locomotives or doubling -or even tripling- a
hill (One locomotive breaking the train into sections and taking them
up the grade one chunk at a time; then re-assembling the train at the
top.) rather than just run his trains around in circles.
In short; you need to first define what sort of railroad you want to
build and what you want to do with it. The answers to those questions
will dictate what sort of grades you can use for your particular
purposes.
~Pete
It would be of great help if you accepted the metric system.
Then that 2%, which is what I also use as a maximum, translates into 2 cm
rise per meter. Or 2 m per 100 m. It can be so simple..
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