firefabric Posted December 4, 2022 Hello, I finished my latest MOC, the Sierra Railway No. 3 Locomotive a.k.a. the Central Pacific Railroad Locomotive 131 (known from Back to the Future Part III). This is my first train MOC, I've mainly stuck to making cars so far as they have been a bit easier subjects but as a long time Lego Trains fan (7740 being my all-time favorite Lego set and my prized possession) a train MOC has been high on my wanted list. I chose the Sierra Railway No. 3 Locomotive as my subject as I like steam locomotives, and in my mind the looks of the No. 3 is more or less the exact definition of a classic steam locomotive. It's also a bit smaller in size compared to later steam locomotives, so after some initial sketches and trials I felt it would be well suited to build in 8-wide scale. It was a fairly long process to complete, I had the basic knowledge of Lego trains but had to study quite a bit and learn about the pitfalls of Lego steam locomotives especially. I wanted to use the Powered Up components to motorize it, and initially I settled on the idea to take the "easy route" and have a regular train motor and battery box in the tender, as it would be the reasonable thing to do. However, after some trials I quickly realized it's not going to work, the axle spacing and the general look of the tender was not compatible with the train motor. Then I considered using the train motor as the front bogey of the locomotive, but it didn't really match that either and moreover, the battery box would not have fitted into the boiler above the front bogey to give the traction needed. All these things you more experienced train builders would have probably been able to tell me straight ahead... So I was left with the solution of installing a PU Technic L-motor and the battery box directly into the chassis of the locomotive and make the big main wheels driven. With that, I also chose to make the cab and boiler detachable from the chassis to be able to change the battery. That setup also needed quite a lot of testing with different options to figure out what kind of wheel base and configuration I can use so that the train will still be able to go through the curved Lego tracks. Turns out as you increase the wheel base, the friction starts increasing surprisingly quickly. So I settled with the configuration as seen in the pictures, which I think is the maximum to have the train still run reasonably well. It already slows down a little in the curves like this, but it's not too bad yet so I felt it was a decent compromise between looks and function. One challenge was also creating the gearbox and the connecting rods for the wheels, I experimented with many different ways with having the motor drive connected to one set of driving wheels and the liftarm connection rods driving the rest of the wheels. I suppose you already know that it didn't work at all in Lego form, seemed to be mainly caused by the fair amount of play in the liftarm pin connections. So the solution that finally worked well was to couple all three axles with gears so they rotate synchronized, and have the connection rod as a "display piece". That also enabled me to use the tehcnic axles instead of liftarms (the connections won't come off), which I felt looked better. The piston rod is still a liftarm, and it's connected to the front driving wheel instead of the middle like in the real locomotive, but that I accepted as a compromise I can make due "Lego limitations"... I wanted to use regular Lego parts at least for now for my first train build, so I wanted to keep it relatively simple. At some point of the build I realized that if I have it motorized, why not lighted as well, and there is another port in the battery hub to add the PU light. However, it had 2 lights and I only needed one above the boiler in the front, so had to figure out where to hide the other light. So out of necessity became an idea to attach the other light to the other end of the boiler to mimic the glow from the fire burning in the furnace of the boiler. That worked out quite nicely, but mostly by accident... The only problem with the light is that there doesn't seem to be a way to control it perfectly; when using the regular remote it can be switched on/off but the motor is also only on/off, which works but it's not very convenient. When using the Lego app (for the Crocodile Locomotive) the motor can be run with different speeds but there is no button for a light. So might need to look into creating some simple control app myself at some point. I experimented with different gear ratios for the Technic L-motor, but in the end I found using 1:1 ratio seemed to be optimal. It's the same ratio as used in the Crocodile Locomotive, so this one is also not very fast. But on the other hand it gives a fair amount of torque which also helps in keeping the locomotive going around the curves with minimal speed loss, and it can pull at least a few cars without major issues. I created a small video to show how it goes around the corners: https://www.youtube.com/watch?v=QSolg3vHgTQ And finally, I of course had to make a small diorama after changing the decals to the Central Pacific Railroad 131 version, it's very simple for now but maybe I'll try to make some enhancements at some point later on: It was quite a challenging project overall but I enjoyed building it quite a bit and finding out many new things about Lego trains in general. I will probably look into making some train cars for it as well at some point but no concrete plans yet. I also enjoy creating instructions for some builds I make, for this I initially thought I probably won't make them as it would be quite a lot of work due to the size and piece count (948). But in the end I decided to try it out anyway, and yes It was a fair amount of work but I had quite a lot of fun, it's a bit like pretending making a set (with much much less restrictions than real sets I presume...). You can check out the end result here. Thanks for checking out my train build! Share this post Link to post Share on other sites
Murdoch17 Posted December 4, 2022 "Is this a stickup?" "It's a science experiment!" Fantastic MOC of a very well loved loco! If this is your first steamer, I can't wait to see what you tackle next! Share this post Link to post Share on other sites
firefabric Posted December 4, 2022 9 hours ago, Shiva said: Thumbs up :) Thanks! 8 hours ago, Murdoch17 said: "Is this a stickup?" "It's a science experiment!" Fantastic MOC of a very well loved loco! If this is your first steamer, I can't wait to see what you tackle next! Thank you! I actually wanted to print the "It's a science experiment!" line on the side of the diorama the same way they do nowadays in the official Lego diorama sets! Yes this was my first train MOC, I've been wanting to make one ever since I started building more MOCs so I've been trying to gather the knowledge and guts to try it out... Share this post Link to post Share on other sites
Murdoch17 Posted December 4, 2022 (edited) 3 minutes ago, firefabric said: Thanks! Thank you! I actually wanted to print the "It's a science experiment!" line on the side of the diorama the same way they do nowadays in the official Lego diorama sets! Yes this was my first train MOC, I've been wanting to make one ever since I started building more MOCs so I've been trying to gather the knowledge and guts to try it out... It's REALLY good for a first train MOC. Seriously, you should be pretty proud it turned out that well. (Most people start off small, copying a BNSF loco or Emerald Night and going from there, but you didn't do that, so kudos to you!) Also, congrats! You've been front-paged by a mod! Edited December 4, 2022 by Murdoch17 Share this post Link to post Share on other sites
firefabric Posted December 5, 2022 20 minutes ago, Murdoch17 said: It's REALLY good for a first train MOC. Seriously, you should be pretty proud it turned out that well. (Most people start off small, copying a BNSF loco or Emerald Night and going from there, but you didn't do that, so kudos to you!) Also, congrats! You've been front-paged by a mod! Thanks again for the kind words! I have to say I'm quite surprised I actually got it working at all, I had some ideas but wasn't sure if they would be any good in reality. Needless to say there was also quite a few different versions of the mechanisms and test setups to figure out why things that seemed obvious didn't actually work... And wow I didn't notice it's on the front page now, thanks for the heads up! And of course thank you to the Eurobricks moderators for the acknowledgement! Share this post Link to post Share on other sites
Feuer Zug Posted December 5, 2022 Great MOC and first foray into trains. The details on your 4-6-0 are well done and recreate the locomotive perfectly. I like your lighting solution as well. Share this post Link to post Share on other sites
LEGO Train 12 Volts Posted December 5, 2022 Top notch work! Share this post Link to post Share on other sites
Legosim Posted December 5, 2022 This is really, really awesome. I can't believe this is your first time building a train, as well! Looks like you've already got in on lock. Share this post Link to post Share on other sites
firefabric Posted December 5, 2022 12 hours ago, cava said: Very nice MOC!!! Thank you! 8 hours ago, Feuer Zug said: Great MOC and first foray into trains. The details on your 4-6-0 are well done and recreate the locomotive perfectly. I like your lighting solution as well. Thanks, much appreciated! I tried to include all the details which kind of stand out on the real locomotive to give it a similar overall look, but also left out many smaller details to keep it simpler. The lights were more or less the only solution I could think of, but in the end it actually turned out looking quite nice. 1 hour ago, LEGO Train 12 Volts said: Top notch work! Thanks! Looking at your signature image, I need to mention the Sierra Locomotive is actually currently sitting on the shelf next to the 7740 with its extra sleeper and postal wagons! Share this post Link to post Share on other sites
firefabric Posted December 5, 2022 14 minutes ago, Legosim said: This is really, really awesome. I can't believe this is your first time building a train, as well! Looks like you've already got in on lock. Thank you for the compliment! This is indeed my first train, but I have to say I've been following the train builds here (and elsewhere) with interest for quite some time and the ideas have been brewing up in the meantime. I also seem to enjoy doing things in an incremental way, there was quite a lot of testing and trying different setups until I even got to a level where the locomotive would actually be kind enough to move properly... Share this post Link to post Share on other sites
Darkkostas25 Posted December 7, 2022 Great MOC, very nice and neat little details for boiler cab and bogies Share this post Link to post Share on other sites
firefabric Posted December 7, 2022 On 12/6/2022 at 3:26 PM, GoHabsGo said: Simply amazing ! Thank you! 19 hours ago, Asper said: Wonderful! Thank you! 14 hours ago, Darkkostas25 said: Great MOC, very nice and neat little details for boiler cab and bogies Thanks, happy to hear you like it! Share this post Link to post Share on other sites
LEGO Train 12 Volts Posted December 8, 2022 On 12/6/2022 at 12:07 AM, firefabric said: Thanks! Looking at your signature image, I need to mention the Sierra Locomotive is actually currently sitting on the shelf next to the 7740 with its extra sleeper and postal wagons! Wow, this is definitely a very good companionship! Share this post Link to post Share on other sites
Paperinik77pk Posted December 8, 2022 Very nice subject and realization! You must be proud of it because it's really, really well done... 😍😍😍 ...and front page is fully deserved!!! Ciao! Davide Share this post Link to post Share on other sites
firefabric Posted December 9, 2022 On 12/8/2022 at 11:17 AM, Paperinik77pk said: Very nice subject and realization! You must be proud of it because it's really, really well done... 😍😍😍 ...and front page is fully deserved!!! Ciao! Davide Thank you, I'm happy to hear that! Yes I also like how it turned out, because initially when I started I had no idea if I would be able to realize what I had in mind (especially in real bricks so that it would actually function properly). And I have to say I'm also surprised how well it has been received, thank you again for all the support, it's much appreciated! Share this post Link to post Share on other sites
