[MOC] 7-wide 2-6-4 Fairburn tank

[Dutchiedoughnut]

Its a concern... So I took my Lego trains and tried the wheelbase in my real life models and while there was some additional friction, it was nothing major.

[Dutchiedoughnut]

Next to the party is a 3-axle Milk Van. It'll get white lettering (EXPRESS DAIRY - MILK FOR LONDON) and I'm sure you can work out I've based it on the milk van preserved at Didcot Railway Centre ;).

It's a 3-axle carriage, so it is articulated to take those tight corners:

[jtlan]

It's a 3-axle carriage, so it is articulated to take those tight corners:

Is that just two pivots? With articulation like that the car will just spin and fall off the tracks, unless there's some sort of spring force trying to force the wheels straight. Better to articulate it 2-and-1 (2-axle truck + 1-axle truck), or use a sliding center axle (might be a lot of friction with something this long though).

[Dutchiedoughnut]

Indeed. I guess making it a 1 pivot carriage is easiest, just remove the one pivot. I'd like to make a sliding center axle but that's a bit trickier due to space constraints. I've only realised this after I posted the screenshots.

[jamesed_1971]

Nice looking Steam Locomotive and rolling stock.

[BrickKnock]

Any updates on your steam loco? :)

[Dutchiedoughnut]

Well yup. I had half-built it but I was missing some parts and some elements didn't quite work.

Soon I will take an inventory of the parts I have and which I have to order. And there will be pictures of the current design and the changes in LDD :).

[Dutchiedoughnut]

Actually a lot has happened since the last picture of the 2-6-4 earlier this thread. The train motor is out of the design now, and a single M motor took its place. It had a huge impact on the design. Nearly as significant is the choice to make the engine dark green. You don't have as much parts available in dark green, so I had to rethink various parts of the design.

Here is the updated drive train:

And the new exterior:

To the left is the tank engine I tried to build. The light green parts weren't available in dark green. The headlight bricks in particular posed quite a problem to get right for a dark green tank. As you can see - in the tank engine to the right - I had to rethink the side panels completely. I think the old side panels look a little better, so I would go with them for a black engine. But the dark green looks great!

I love the size of the engine. It appears to be rather short and stubby on the computer screen, in real life it looks a lot longer. It is 32 studs long and 7 studs wide which should give you some idea about its size. I love the cab and boiler design. The boiler is a little bit smaller than the Emerald Night boiler. Combined with the 7 studs width, it is a good size for this engine. The articulated chassis seems to work really well. I couldn't get the gears I needed so it doesn't run right now. Pushing it through a series of S curves worked really well. I'm also pleased with the drive train. All six drive wheels are driven because I had binding issues when I tried to drive only one axle and connect the others with the cylinder rods.

Some other things didn't work so well.

The front boiler design turned out to be really fragile. In fact, I drove myself nuts trying to put it together. It used a whole lot of 1x1 bricks and a single 2x4 piece which required too much force to fix it to the 1x1 pieces. Each time I tried I would destroy my attempt. I decided to change the 1x1 bricks to 1x2x2 bricks. It also allows the smokebox door to sit flush to the smokebox.

My biggest issue is that while the cab as a whole is pretty sturdy, the cab assembly pops right off from the chassis. There is no strong connection between the firebox and the cab which causes the fragility. The boiler is 4 wide while the cab is 7 wide, it's not easy to connect the two unless you use some technic bricks:

There were no other structural issues, just cosmetic. I am experimenting with a chain coupling rather than Lego's magnets. I can't recall huge magnets hanging off real trains ;), and I can't buy the separate magnets from my local stores. Here is a quick view of the coupling. The main coupling would be a 3 studs long half-width Technic brick. I'd love to use Lego chains as secondary coupling. Real examples would have those just in case the main coupler fails.

[bricks n bolts]

Loving your work DutchieDoghnut

For the drive version how did you gear up the drive wheels from the M motor?

[Dutchiedoughnut]

It's geared down 8/20. So its not going to be a speed demon, but it will pull a few carriages im sure.

[Man with a hat]

I love the chain coupling solution.

I wonder why not more people have come up with it.

[Dutchiedoughnut]

It might be very unreliable ;).In any case it's not as easy to couple or uncouple cars. Then again, there is no danger of pulling more cars than a magnet can handle.

[xboxtravis7992]

Yeah that chain coupler looks good for European trains. Remove the buffers and chains and leave the link and it looks like it could be early American Link and Pin couplers.