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Subject: 
Re: Track slope...
Newsgroups: 
lugnet.trains
Date: 
Wed, 21 Apr 1999 02:32:17 GMT
Reply-To: 
lpien@iwantnospam.ctp.comNOMORESPAM
Viewed: 
1297 times
  
Good topic!

Stephen F Roberts wrote:

...So anyway, what's a good height for an overpass? Mine was 13 high and was
kind of close.

13 is a bit low for anything oversize, IMHO, but I model 'merican. It's
probably OK for eurotrash stuff.

And what's a good slope? Should I start the slope at 1, then go
to 2 plates per segment (a number I had heard)? And should I keep the slope on
curves at 1?

Good question. Just as with real railroads, the answer is "it depends".

Your slope in general is limited by the horsepower to weight ratio
you're willing to spend. As you increase the slope, adhesion also comes
into play. At 3 plates per track segment you are going to have a hard
time pulling even 1 or 2 cars up a grade with a single motor, as you
observed. A motor by itself will have a hard time at 4 plates per slope
unless you add extra weight to improve adhesion (this is counter
intuitive until you think about it! :-) ).

As with real railroads, you can, from an energy budget perspective,
exceed the sustainable slope for a short period if you're willing to use
momentum to get you over the hump. You can also use racks, if you can
figure out how. I recall that Brian Lanning was working on this but
don't know what the ultimate outcome was.

I tend to use 1 plate per slope, but I like long trains and usually
budget 2 motors per locomotive anyway.

Now, that's theoretical grade work. As in real life, you also have to
allow for transitions, you should not change the rate of change in
elevation by more than 1 plate per section, so to get to that monster 4
plates grade, you should be using 3 transition segments of 1, 2, and 3
plates of increase.

Another tip. Never change the rate of change on a curve, or on the
section next to it. You can get away with two plates per section, even
curved, without derailments, if you come into and exit the curve at the
same grade.

For some fascinating reading on this topic, go to a used book store and
find a civil engineering text that predates WWII. Matt Bates's site has
info on this as well.

--
Larry Pieniazek    http://my.voyager.net/lar
FDIC Know your Customer is wounded, thanks to you, but not dead...
See http://www.defendyourprivacy.com for details
For me: No voyager e-mail please. All snail-mail to Ada, please.
- Posting Binaries to RTL causes flamage... Don't do it, please.
- Stick to the facts when posting about others, please.
- This is a family newsgroup, thanks.



Message has 2 Replies:
  Re: Track slope...
 
(...) Not having access to a used book store, why a civil eng text from before WWII? Did that data become classified after WWII? (25 years ago, 21-Apr-99, to lugnet.trains)
  Re: Track slope...
 
(...) Eurotrash!! That's the name of a TV Program. You're just jealous that European Passenger trains can run at 186mph. (...) Are the metal rails magnetic? If so you could use Superhedsion(TM) basically using magnets to improve traction. (...) How (...) (25 years ago, 21-Apr-99, to lugnet.trains)

Message is in Reply To:
  Track slope...
 
...I massively underestimated the minimum clearance for my first attempt at an overpass and so had to increase the slope of the track to get it up high enough. I ended up with 1 brick per segment, but had a lot of trouble getting the train to (...) (25 years ago, 21-Apr-99, to lugnet.trains)

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