[MOC] [Instructions] GWR Small Prairie steam engine

[sebulba56]

Hi there !

I’m back again to present another train. I briefly mentioned it when I showcased my Flying Scotsman, and here it is now: the Small Prairie. This locomotive was operated by the GWR (Great Western Railway) (yes, another British one !) throughout the first half of the 20th century.

First of all, I produced building instructions for all of these if you’re interested.
Small Prairie instructions: https://rebrickable.com/mocs/MOC-251026/Sebulba56/gwr-small-prairie/#details

French‑style flatcar (Free): https://rebrickable.com/mocs/MOC-248565/Sebulba56/french-style-flatcar-wagon/#details

American‑style flatcar (Free): https://rebrickable.com/mocs/MOC-250918/Sebulba56/american-style-flatcar-wagon/#details

It’s a tank engine, particularly useful in situations where you need to run in both directions without turning the locomotive around. This one is among the larger tank engines, with a 2‑6‑2 wheel configuration. Below is a photo of the real engine, followed by my MOC.

 

 

For my LEGO reproduction, I decided to go with an 8‑stud-wide build (unlike my Flying Scotsman). The main reason is technical: I wanted to fit all the electronics required for propulsion inside the locomotive. Aesthetically, this scale also allows for a more accurate and detailed model.

 

 

 

It was a real challenge to cram the huge Powered Up hub and the L‑motor inside without ruining the overall look. I had to design the whole structure around these two components, which actually ended up playing structural roles:

• The motor supports the boiler and provides the half‑plate offset needed for a clean connection between the boiler and the side tanks.
• The hub is anchored inside the cab and helps keep it stable.

This design choice does, however, come with two major drawbacks:

• Accessing the electronics is particularly complicated. That is pretty annoying when you need to replace the hub batteries.
• It’s impossible to add any cab interior details, since the hub takes up all the space.

 

In the end, despite these inconveniences, I think this design approach is quite relevant. The loco runs very well and has plenty of power thanks to the significant weight on the driving wheels. Its compact and well‑balanced shape allows it to handle tight LEGO curves smoothly. It can therefore pull fairly long and heavy trains without much trouble. I posted some videos of it in action on my Instagram (@sebulba_creations) if you're interested.

 

 

 

I also took the opportunity to build two small wagons to go with it. One is in a rather French style (the two‑axle one), and the other more American (the one with bogies). Both can carry a variety of loads thanks to their configurations. The French one even has folding sides, making it suitable for transporting bulk materials.

 

 

 

As for what’s next, a BR Mk1 coach in white/dark blue livery to go with the Small Prairie is coming soon : I’m currently waiting for my Bricklink orders. The Shinkansen project is also still ongoing; I’m making steady progress. I’ve been experimenting a lot with the various slopes and wedges released in recent years, and I think I’m finally on the right track (a glimpse of the WIP down below).

That’s it for me, see you next time !

 

Edited February 11 by sebulba56

[Darkkostas25]

Nice "Set". Lovely engine and cars. Intriguing Shinkensan

[JopieK]

Very nice @sebulba56. Many nice details you put in. Thanks for sharing and looking forward to the updates on Shinkansen!

[zephyr1934]

The engine and cars came out looking good.

15 hours ago, sebulba56 said:

Out of context that looks like you've built 4 art deco space cars and a matching truck (Flash Gordon style). And then with context, I now realize that if you cut the nose off a Shinkansen you'll get a space car. You've done a good job with the shaping.

[TeddytheSpoon]

Nice model(s)! Is that Keighley and Worth Valley Railway red? Or was GWR dark green simply too expensive? (I've discovered this same problem during designs of my own...!)

The Shinkansen also look fascinating.

[Feuer Zug]

Great little tank engine. Using the motor and hub as major parts of the chassis is nifty. 

[L-Gauger]

Excellent work, @sebulba56! I like how much detail you were able to fit into this 8-wide model. Seeing the official Lego steam drive wheels reminded me of something I recently discovered: some brands of barbecue lighters have black rubber grip rigs around the handle that, when removed, fit perfectly on the Lego drive wheels. Lego did make the right size rubber bands in black, but they're really expensive. The BBQ lighter rings look just like the official part, and (for me at least) they were free.  I'll have to share photos at some point. 

[Sven J]

A beautiful model with some ingenious design features!
I'm currently building a small 2-6-2T myself (in 1/32 scale for 45 mm track, but nevertheless not much longer than yours), so it's even more interesting to see your approach.

[LL1982]

It looks awesome. Like how you all fit it in and make it work. It does mean no cab interior, but you got the minifig hanging on the side 😉. 

Wagons also very nice. Love these 'simple' but very useful design.

Love the section view also gives an idea on the building.

[LEGO Train 12 Volts]

I don't know which is more fascinating, the locomotive or the beautifully crafted carriages ...excellent quality of MOCs!

The lantern on the back of the steam locomotive is stunning...it's the first time I've seen this original design.

[sebulba56]

On 2/12/2026 at 7:40 AM, zephyr1934 said:

The engine and cars came out looking good.

Out of context that looks like you've built 4 art deco space cars and a matching truck (Flash Gordon style). And then with context, I now realize that if you cut the nose off a Shinkansen you'll get a space car. You've done a good job with the shaping.

Thx ! Haha yes the Shinkansen is indeed a strange looking one. The one I am modelling is the N700S version, the most recent one thats runs Tokyo to Fukuoka trough Kyoto and Osaka. Since my post I made some progress on the shaping and finally built the front with real bricks. Would anyone be interested in a WIP topic ?

On 2/12/2026 at 2:15 PM, TeddytheSpoon said:

Nice model(s)! Is that Keighley and Worth Valley Railway red? Or was GWR dark green simply too expensive? (I've discovered this same problem during designs of my own...!)

The Shinkansen also look fascinating.

 Thanks ! You saw it clear. I first wanted to do it in classic green but it would have been too similar to my Flying Scotsman. Then i was thinking about dark green indeed but like you said, it is pretty expensive and the 1x2 inverted arch do not exist in this color (those are pretty important for the shaping of the cab). During my research I saw that a dark red/maroon livery existed so I went for it ! Altough that particular one do have slopped tanks so mine is not precisely accurate to a real life locomotive. Maybe when Lego will do the arch in dark green I will consider a rebuild in this color.

On 2/13/2026 at 11:03 PM, L-Gauger said:

Excellent work, @sebulba56! I like how much detail you were able to fit into this 8-wide model. Seeing the official Lego steam drive wheels reminded me of something I recently discovered: some brands of barbecue lighters have black rubber grip rigs around the handle that, when removed, fit perfectly on the Lego drive wheels. Lego did make the right size rubber bands in black, but they're really expensive. The BBQ lighter rings look just like the official part, and (for me at least) they were free.  I'll have to share photos at some point. 

Thanks for your feedback ! Do you have a link or an image of what you are talking about ? I am pretty curious if I could find a alternative here in France.

17 hours ago, LL1982 said:

It looks awesome. Like how you all fit it in and make it work. It does mean no cab interior, but you got the minifig hanging on the side 😉. 

Wagons also very nice. Love these 'simple' but very useful design.

Love the section view also gives an idea on the building.

Thx ! Putting minifigs on it gives it more life i like it. You can also put ones on the plating right next to the boiler it looks good. You perfectly understood what I was going for with the wagons : simple and efficient. Both of them are around 120 pcs (10$ not counting the wheels and couplings) so they are pretty cheap to mass-produce.

[zephyr1934]

21 hours ago, sebulba56 said:

Since my post I made some progress on the shaping and finally built the front with real bricks. Would anyone be interested in a WIP topic ?

That would be interesting, and that would also keep the threads on single topics

[L-Gauger]

On 2/16/2026 at 3:12 AM, sebulba56 said:

Haha yes the Shinkansen is indeed a strange looking one. The one I am modelling is the N700S version, the most recent one thats runs Tokyo to Fukuoka trough Kyoto and Osaka. Since my post I made some progress on the shaping and finally built the front with real bricks. Would anyone be interested in a WIP topic ?

On 2/12/2026 at 7:15 AM, TeddytheSpoon said:

Yes, definitely! 

 

On 2/16/2026 at 3:12 AM, sebulba56 said:

Thanks for your feedback ! Do you have a link or an image of what you are talking about ? I am pretty curious if I could find a alternative here in France.

Here's the exact brand I used: https://elitebrandsusa.com/products/windproof-multipurpose-utility-lighter

However, any lighter with grip bands of similar dimensions ought to work. Does that help you? 

[Shiva]

Nice tank locomotive :)