Re: A question about grades

In article <1173972410.448635.54400@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
pawlowsk002@xxxxxxxxxx wrote:

grades of maximum 4.5%. This makes me wonder if this is some sort
of 'magic number' for model trains - the highest, perhaps, that you
can
get without starting to have major traction problems, or maybe the
steepest that looks realistic?


Real railroads would only use the maximum grade necessary. Granted, at
times that means grades up to 14% (the steepest grade I know of in the USA
where normal locomotives were used), but on that type of grade you will
only see a locomotive and two empty cars or so (the particular 14% grade I
know of was on a logging line - where empties went uphill and loads went
down).

For model railroads, the "magic number" depends a bit on the locomotive
and track. The material used in the wheels of Athearn diesel locomotives
during the 1980s gave very good grip, and many other locomotives from
other manufacturers would not perform as well. The more slippery material
used on some other models could be overcome by adding weight to the
locomotive.

Adding weight must be done with some care. You want the locomotive to be
able to spin the wheels if the load is too heavy for it, as locking the
motor in place will cause it to burn out. So, the common philosophy I
have heard is that any weight added to the locomotive that still allows
the wheels to spin when the locomotive is trying to move an immovable
object (such as a wall) is an improvement.

Another issue is going to be how free rolling your freight cars are.
Slippery plastic does wonders for free-rolling cars, but a bit of gunk in
the bearing area can cause a significant decrease in how well they roll.

Unfortunately, your best bet to find the answer to your real question is
to do some experimentation with your models and the grades on which you
want them to operate. You may find it necessary to assign only special
power to your steepest grades, but then again that is what the real
railroads did.

--
-Glennl
The despammed service works OK, but unfortunately
now the spammers grab addresses for use as "from" address too!
e-mail hint: add 1 to quantity after gl to get 4317.
.

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