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Subject: 
Re: Articulation with "working" connecting rods
Newsgroups: 
lugnet.trains
Date: 
Tue, 5 Sep 2006 20:50:27 GMT
Viewed: 
2176 times
  
In lugnet.trains, Sebastian Dyson wrote:
I'm trying to design an 8-wide 4-8-4 using Big Ben's wheels (CAD only, I'm but a
poor student), and want the loco to be able to negotiate standard Lego curves.
As the leading truck has an axle each side of the cylinders, I'm finding it hard
to keep the cylinders fixed relative to the driving wheels without the cylinders
and/or rods fouling the wheels of the pilot truck.

I could raise the cylinders, as in Rosco's X class
(http://www.br-eng.info/about/lego/mocs/x-class.htm), but I'd really prefer not
to, as the prototype's cylinders are quite low (the bottom edge of the cylinder
is about level with the leading truck's axles), and I can only move them so far
outboard before they look ridiculous.

Another option is to have no connection between the rods on the wheels and the
cylinders and have the cylinders turn with the leading truck, which seems a
little like cheating.

So if anyone's got any tips or experience in this, I'd love to hear it.

Since you have 8 coupled wheels, some of the sets need to use blind drivers.
The easiest solution therefore is to make all 4 sets use blind drivers, suspend
them all off the rails by having the leading and trailing 4-wheel sets as the
bogies, drive the 8-coupled wheels with a 71427 or 43362 technic gearmotor, with
an electrical connection to the train motor, which is either the rear engine
bogie, part of the tender or both for a 2-motor engine.

That's how I've done most of my steam trains, 0-6-0s, 2-6-0+0-6-2, 4-6-0 and
2-10-0.  The last two have used 40-tooth cogs and the others 24mm pulleys with
tyres to make them 30mm - a similar size to BBB wheels.  I have also
experimented with model team wheels with tyres for a 4-8-4 configuration.  The
40-tooth cog engines have 2 gearmotors to drive the wheels.

4-6-0: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1953724

2-10-0 (with an extra pair of cheat wheels!):
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=116051

The 2-6-0+0-6-2, with swivelling motor behind the driving wheels, did get a bit
wide: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1093563

Mark



Message is in Reply To:
  Articulation with "working" connecting rods
 
I'm trying to design an 8-wide 4-8-4 using Big Ben's wheels (CAD only, I'm but a poor student), and want the loco to be able to negotiate standard Lego curves. As the leading truck has an axle each side of the cylinders, I'm finding it hard to keep (...) (18 years ago, 4-Sep-06, to lugnet.trains)

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