Subject:
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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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Mon, 4 Sep 2006 18:33:51 GMT
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Viewed:
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2169 times
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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.
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.
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Message has 10 Replies:
 | | Re: Articulation with "working" connecting rods
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| (...) Not sure I can help you much here - I designed my cylinders to be quite flat so they could slide 'twixt motor and soleplate. With small BBB wheels on the front your front truck is lower than a standard motor, but if you say Rosco's are too (...) (18 years ago, 4-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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| (...) Hello Sebastian, The best I've manage to work out on this is with my 4-8-4 Northern engine as shown at: (URL) In this case, I put the leading wheels forward of the steam cylinders. The cylinders stay attached to the same bogie/truck that drive (...) (18 years ago, 4-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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| (...) snip (...) Actually I wouldn't call that cheating at all, I'd call it compromise. And as far as I'm concerned, compromise is fine (even necessary!) in building LEGO models. I would probably do something like Teunis did in his S-class, but (...) (18 years ago, 5-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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| Ok I think I have something. Each cylinder is free to slide longitudinally on the frame. This movement is constrained by a vertical pin (or 1x1 round brick) on each side of the pilot truck. These pins engage a transverse groove (currently a pair of (...) (18 years ago, 5-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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| (...) 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, (...) (18 years ago, 5-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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| (...) Sebastian, Here's my 2-10-4 using BBB wheels. I used Technic Flex-System Hose (URL) to go from the cylinders to the drivers. Pictures can be found here: (URL) It does navigate points and curves most of the time :). Its still a work in (...) (18 years ago, 9-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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| (...) As a train novice I don't know how much help I can be, but since I don't remember reading this idea thus far in the thread, I'm just going to throw it out there: shrink the wheels. I ran into this problem once before, and while designing a (...) (18 years ago, 11-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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| (...) An alternative solution, more complex than what I wrote earlier, uses a method similar to Mike's, in that flex tubes allow the set of drivers to be split into blocks, but different in the way the blocks are linked and kept synchronised. The (...) (18 years ago, 15-Sep-06, to lugnet.trains)
| | | Re: Articulation with "working" connecting rods
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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 (URL) 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" (...) (16 years ago, 20-Feb-08, to lugnet.trains, FTX)
| | | Re: Articulation with "working" connecting rods
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| (...) Indeed, it is good to get all the right parts in all the right places. It is also great to see the compilation of so many solutions that people came up with. I'm surprised that Neither Ben nor Anthony pointed out the idea of splitting the (...) (16 years ago, 21-Feb-08, to lugnet.trains)
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