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Oops, I wanted to post this to .announce.moc as well ...
-s
>
> Hi all,
>
> I uploaded pics of my 4-6-4 Hudson steam engine and tender this afternoon.
> They can be found at:
>
> http://www.brickshelf.com/cgi-bin/gallery.cgi?f=22292
>
> A couple of points about the engine:
>
> (1) For once, I can recount the exact date of conception for the project! I
> started working on the design for this on April 29th of this year.
> Interestingly, this *exactly* coincides with John Neal's post about his son
> Ross's amazing 4-6-2 Pacific engine:
> (http://www.brickshelf.com/cgi-bin/gallery.cgi?f=16328). I was inspired by • the
> amazing detail on that engine to try another design of my own.
>
> (2) This engine features two (2!) pairs of working pistons; both the drive
> pistons and the valve pistons reciprocate in the cylinders. Additionally, the
> two pistons have different accelerations, and slightly different phases, a
> feature which is accomplished using a levered linkage. The actual mechanism
> for regulating the valve pistons is much more complicated than what I • depicted,
> but I felt that the compromise still offerred a pleasingly aesthetic
> representation. I included a number of 15-second movie clips that demonstrate
> the working of the pistons as the engine is moving along the track.
>
> (3) The drive wheels actually ride on top of the rail, as is the case with
> Ross's design. This provides for the use of some interesting driver wheel
> choices. The driver wheels on each side are geared together with 24-tooth
> gears in order to maintain alignment, and prevent binding with the linkages.
> In order to pull this off, 5 24-tooth gears were needed for each side: one
> attached to each wheel, and then two idler gears. As a further challenge, the
> idler gears had to make use of 1/4 stud offsets to maintain the correct
> spacing. The three driver wheels on each side are furthermore on separate
> axles as the wheels on the other side, so that the two sides can rotate at
> different rates as the train rounds curves.
>
> (4) In addition to the shining headlight, the coal furnace actually works! I
> used four of the old style 1x2 bricks with a light on top to achieve this
> effect. With all of them oriented to blink mode, the varying frequencies
> produces a nice "flickering" effect. Mounted behind a wall of 1x1 trans-red
> plates, and a number of trans-orange flame pieces, the furnace appears to have
> a rich red flame. Both the head lamp and the furnace are powered from a 9V
> battery box hidden in the tender. The switch is hidden under the coal in the
> tender's bed. I included a few 15-second movie clips that show the effect;
> unfortunately, in movie mode, my camera insists on continual auto-focus, so • the
> overall clarity isn't great (What with the changing lighting conditions), but
> you should be able to get the effect.
>
> (5) The cowcatcher! After a thorough search that didn't uncover any designs
> which emulates the look I was going for, I came up with this design. I also
> produced a 6-wide version, which I'm hoping to see on a steam engine sometime
> soon: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=21720. In any case, • I'm
> pleased with this design.
>
> (6) Oh yeah ... under the heading "best laid plans of mice and men oft go
> awry" comes the fact that the engine comes is 10 wide. I intended it to be 8
> wide, but when the walkways were added on each side, and all of the linkage
> pieces, the predominant width is definitely 10 studs. However, at the • pistons,
> the width actually creeps up to about 12 studs.
>
> (7) Unlike my usual fanatacism for collecting entire tomes of source • material,
> I built this design from one image:
> http://www.brickshelf.com/cgi-bin/gallery.cgi?i=217960. I found several • others
> in looking around, but none that captured the details I really wanted to
> include. In the end, this is the only one I referred to.
>
> (8) It does go around curves, switches, and crossings. The only wheels that
> actually run in the tracks are the four leading wheels and the four trailing
> wheels, all of which are actual LEGO train wheels (the forward ones being the
> old style, the trailing ones being the contemporary design). The driver
> wheels, as mentioned above, actually wide on top of the rails, and therefore
> can pass over any layout. That being said, it's still a heavy steam engine.
> When it starts to get some distance from the power source, it tends to slow
> down and *gasp* stop. Ahh well.
>
> Hmm, I guess that's about it. Thanks for looking!
>
> -s
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