Subject:
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Re: Articulation with "working" connecting rods
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Newsgroups:
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lugnet.trains
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Date:
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Wed, 20 Feb 2008 09:49:48 GMT
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Viewed:
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17588 times
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A long time ago, in lugnet.trains, Sebastian Dyson wrote:
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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.
(snip)
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Bit of a blast from the past, but I kinda didn’t get around to doing any of this
and forgot all about it until Cale’s
Y6b put it back in my mind. I’d not thought of building a 9-wide before, but it
certainly gives the loco a “muscular” look.
This got me back to thinking about leading bogies and cylinders, and after some
tinkering I’ve come up with a solution that has cylinders between axles of the
leading bogie and should still be able to navigate Lego track.
The square in the middle is the top of a Plate 2 x 2 with Pin, connected to a
Technic Liftarm 1 x 3 Straight, and the two “floating” black 2x2 squares are
the cylinders, in the same style as Cale’s Y6b. These are rigidly connected to
the same frame as the driving wheels.
The liftarm acts to pull the bogie forwards when deflected sideways, providing
enough clearance for the flanges to avoid fouling the cylinders. This gives
full-height clearance for 2x2 cylinders set 7 studs apart (for a total of 9
width).
I’ve made MLCad mock-ups on constant-radius turns, from straight to curved, and
on wavy track, and it appears to clear just fine.
Comments? Criticism?
As for the loco type, it’s a secret ;)
Let’s just say it’s big.
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Message is in Reply To:
 | | Articulation with "working" connecting rods
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| 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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