[MOC] Northern Pacific A4 4-8-4 #2678

[thesnoqualmieroute]

Hey all! I wanted to share a little project I have been working on for the past month, as I think it has reached the quality where I feel comfortable posting it. After lurking in the forums for several years, this is my first serious MOC. I first started doing research for this project more than a year ago, as I had always had an interest in the Northern Pacific and Lego trains, but I only started experimenting in Stud.io about 3 months ago and the majority of the work for this project was done in the past 2-3 weeks. (Due to a lack of proper ambition and motivation). I had only attempted one other project before this which was an NP Z8 challenger locomotive but that was entirely a physical build (which proved much more difficult) and I will most likely rework it in Stud.io after I feel satisfied with this build. Theres gonna be quite a bit of yapping in this post so feel free to just gloss over the pictures, and I plan to release a video/review once I physically build her.

This is my rendition of the Northern Pacific's class A4 "Northern" 4-8-4 locomotive, specifically #2678.

First, a little bit of history for those interested: The A4 class was the 4th class of 4-8-4 "northern" locomotives on the Northern Pacific Railway and is often regarded as the pinnacle of that locomotive type design on the railroad. The Northern Pacific was often known for their innovation in steam locomotive design, being the creators of the 4-8-4 "northern" type and 2-8-8-4 "yellowstone" type locomotives, of which the "northern" type became extremely widespread on both western and eastern railroads in the United States. Both these locomotives were expansions of existing locomotive types of their era, with the biggest addition being a larger 4-axle trailing truck to accommodate a larger firebox that was needed to burn the less energy-rich semi-bituminous Rosebud coal (much like the larger fireboxes of camelback locomotives, which was mined from a mine under Northern Pacific's possession and could be as much as 3x cheaper than fully-bituminous coal from the east coast. These initial locomotives were considered modern for their time and were certainly very big, however, they were certainly not as refined as later classes of "northern" locomotives, even those not on the Northern Pacific.

The 8 locomotives of the A4 class, numbers 2670-2677 (2678 does not actually exist) were built by Baldwin Locomotive Works in the months leading up to WW2 as traffic on the Northern Pacific increased as a result of wartime preparations. These locomotives were equipped with the most innovative steam technology of the entire steam era and weighed in at 945,800 lbs including tender, being delivered to the NP at St. Paul for a cost of $184,858.64 each. The characteristic all-weather cabs and large centipede-style tenders are what drew my eyes to this locomotive as they give them a very handsome and modern appearance. These locomotives could be seen in dual service, both passenger and fast freight, between St. Paul, Minnesota, and Livingston, Montana, a distance of 1,008 miles, on the eastern end of the railroad. At times, the locomotives could even be seen heading a streamlined 1947 North Coast Limited!

Equipped with a full set of roller bearings, a high-capacity boiler, integrally cast steel frame and cylinders, a complete mechanical and pressure lubrication system, and improved counter-balancing techniques, these "northern" were certainly comparable in performance to more famous "northern" type locomotives, including the Santa Fe's 2900 class, SP's GS4 fleet, Norfolk and Western 600-series, UP's FEF series and even the New York Central's Niagaras. A majority of those locomotives were tested under artificial conditions, but even then the A4 class was highly regarded as one of the nation's highest-performing locomotives and was a true "modern" steam locomotive at the end of the steam era. Keep in mind, this was with the locomotives burning semi-bituminous fuel which had a fraction of the power of what those other locomotives were getting! The Northern Pacific's modern "northern" locomotives usually don't receive nearly as much attention as other popular "northern"s for a variety of reasons, such as the fact that none were preserved and that they ran through a sparingly populated part of the country, as evidenced by the little amount of photos that exist of them (I found maybe a handful max through books as only  1-2 are available on the internet)

A majority of this knowledge comes from Golden West Books Northern Pacific Supersteam Era 1925-1945

I decided to model this class of locomotive because I live along the former route of the Northern Pacific in Washington State, and because of the locomotive's sleek clean appearance and relative lack of popularity.

Surprisingly enough, I started this project from back to front, as I still needed a tender for my physical Z8 challenger build which has the exact same tender as the A4 class, and I could build it out I Stud.io first before physically building to pair with my Z8. This was actually my second attempt at this style of tender, as I had made a matching 100% physical version with my Z8, however, I was not satisfied with that build (or the Z8 for that matter) and decided to take my first major plunge into the depths of Stud.io. In this design, I wanted to save money by limiting the structural frame and using the tiled walls of the tender to support the whole frame, which was a big gamble in terms of structural stability. I have already built this tender irl, and the design proved solid, however, it does make disassembly a bit tough as taking some parts off can critically weaken the model and a little caution is necessary in handling the model. For the tender trucks, all 7 axles and wheels are there, using BrickTracks wheelsets for roller bearings, and the axles can swing from side to side to take smaller curves. Without the truck side frames, the axles can easily take r40 geometry, but for look's sake and to keep the tender relatively thin, (both the locomotive and tender are 9 wide) I opted to run the tender and locomotive on larger radius curves. Besides that, the tender is relatively simple in construction, with grab irons and other details modeled in as appropriate.

 

For the locomotive itself, going with the philosophy of starting from back to front to design parts that could match a future Z8 challenger build, I started with the all-weather vestibule cab. (of which the Z8 challenger shares) I used the same rail technique for designing the grab irons for the cab as I did for the tender as I felt the better replicated the look of the prototype. Getting the windows to look right while being close to the angled slope of the front of the cab was tough, and I didn't want to use transparent regular bricks for the windows as I felt that they looked unrealistic, but I found no better alternative. Getting the smooth transition between the cab and boiler also proved tough and weakened my motivation to continue with the project as it took a couple of days, however, I am satisfied with the result now. I really liked how all the proportions for the cab worked out, and testing it with the running gear turned out the be a big motivator for me.

The running gear for the locomotive was probably the quickest task for me besides detailing the body with piping work, as I already had a ton of experience working with running gear and even had a physical version of the running gear built for testing purposes. (provided not with all the extra detail that might get in the way) The locomotive is powered by a single PF/PU train motor (YES A TRAIN MOTOR) which is situated inside the boiler on its side. It spins an axle going straight down over the 3rd pair of drivers and is basically a carbon copy of a drive I used in one of my very early locomotives. I chose this drivetrain as it is simple, easy, and reliable, which I really emphasized when I designed this locomotive as I didn't just want this thing to look good but run well too. This drive has plenty of power and speed, especially with Breckland Bricks XXL Boxpox drive wheels, which is prototypical as the A4 class was often praised for running in excess of 100 mph on the good roadbed of the NP and in the prairies of Montana. This configuration, however, can easily be swapped for a more common M or L PF/PU motor. (The red block in the image simulates a train motor)

The boiler of the locomotive is 7 wide, and with the running boards, the locomotive turns out to be 9 wide. A lot of the piping work across the boiler turned out to be surprisingly easy, and the only major issue I ran into was having to extend the firebox by 2 studs as I had messed up the proportions when first building out the boiler. Looking at a few reference images, especially of model versions of this locomotive, turned out to be the most helpful in designing the piping work and making sure it is prototypical. The pilot for the model is just some sloped tiles on a hinge which proved surprisingly clean and one of the best parts of my physical Z8 build, so I copied it over to my A4.

I am very satisfied with the way this locomotive turned out, I love the proportions and I do believe it replicates the original locomotive faithfully. The only things left to do are to complete the valve gear, which I do have experience in, but I am having trouble sourcing Stud.io files for (the ones on Trained Bricks don't seem to be working for me), and a little bit of clean up before I order the parts. I certainly hope this locomotive runs as well as she looks. I am hoping to do a review video once I do order the parts, and I hope to run it wherever I can, however, as of right now I don't know of any potential shows I could go. (Seattle region) I do post a lot more frequently on my Instagram, @thesnoqualmieroute. I hope to finish in time to submit for the BrickTrainAwards under the TFOL category. For now, I'll just treat you to a simple scene I built using some of my 1947 North Coast Limited coaches and a little too much North Dakota wheat that certainly fried my computer. Thanks for ur attention! -The Snoqualmie Route.

Edited October 8, 2024 by thesnoqualmieroute
Typo

[zephyr1934]

That's a great build with lots of subtle detailing, very well done. Technically one NP northern (A3) did survive in a way, in the form of SP&S 700.

[thesnoqualmieroute]

10 hours ago, zephyr1934 said:

That's a great build with lots of subtle detailing, very well done. Technically one NP northern (A3) did survive in a way, in the form of SP&S 700.

Yes! I’ve actually been down to Portland a couple times to see SP&S 700 at the oregon rail heritage center, they have a great facility there!

[Ropefish]

Oh wow this looks lovely! so you're using a train motor sideways to drive the whole thing?

[Feuer Zug]

Exquisite design. Thank you for the history behind the locomotive and features as well as your work in designing and building it.

[thesnoqualmieroute]

9 hours ago, Ropefish said:

Oh wow this looks lovely! so you're using a train motor sideways to drive the whole thing?

Thanks so much! Yes! It has proved very effective in my opinion based on previous experience, with plenty of power and speed. A single motor powers the two axles of the train motor, so the setup makes full use of the motor's power output despite only drawing power from one axle. In addition, the high rpm of the train motor compared to other Lego motors makes it pretty powerful, however, the simplicity of the design and ease of use is what sold me in using this motor setup.

Edited September 11, 2024 by thesnoqualmieroute

[AbleChristopher]

@thesnoqualmieroute this is astonishingly well done! I thoroughly enjoyed the read, in my opinion a project is so much more satisfying when it is accompanied by history and a story. As a fellow PNW native, I too am partial to the fallen flags of the north (Northern Pacific, Great Northern, etc.). There is an industrial beauty to NP's A-series Northerns or Z-series Challengers, Great Northern's Q-series 2-10-2's, etc. I notice many details in your model that give the locomotive that specific Northern Pacific look. I am a part time volunteer on SP&S 700, so I would know. Fantastic work.

[Shiva]

Nice work :)

And cheers for the history too.

Ops, you have done the same error with numbers as I did on friday. 2978 instead of 2678.

Edited September 14, 2024 by Shiva

[thesnoqualmieroute]

19 hours ago, AbleChristopher said:

@thesnoqualmieroute this is astonishingly well done! I thoroughly enjoyed the read, in my opinion a project is so much more satisfying when it is accompanied by history and a story. As a fellow PNW native, I too am partial to the fallen flags of the north (Northern Pacific, Great Northern, etc.). There is an industrial beauty to NP's A-series Northerns or Z-series Challengers, Great Northern's Q-series 2-10-2's, etc. I notice many details in your model that give the locomotive that specific Northern Pacific look. I am a part time volunteer on SP&S 700, so I would know. Fantastic work.

Thank you so much! I was always drawn to the NP and the GN because of their distinctive style of modern locomotives, they just have perfect proportions in my opinion. I tried really hard to match that style with the A4, and I was surprisingly really satisfied, especially after the Z8 didn't turn out very well! I remember @Glenn Holland saying that his version of Nickle Plate #765 was unmistakenly a Nickle Plate Berkshire, and that no one could possible mistake it as any other locomotive in his video, and I think I achieved the same effect. I am especially satisfied considering the various versions of NP Northern's and other similar western 4-8-4's such as the Burlington Route's O-5 class and Milwaukee's S-2, which had the same solid pilot, high boxpox drivers and all-weather cab making them look very similar, however, in my opinion, my model is unmistakenly Northern Pacific, so I consider it a job well done.

17 hours ago, Shiva said:

Ops, you have done the same error with numbers as I did on friday. 2978 instead of 2678.

Oops! Can't believe I missed that

[Shiva]

Easy to miss. I tried to find and get help to find Set 76289, from closest toy store in friday + they checked on their PC's. Set was not on the shelves "76286". I'll try next week again, this time with correct number and see when they get the set in again.

I found the number mistake when trying to google for more pics of this nice locomotive. After switching the 9 to a 6, I could atleast find photos of the nice H0 models :)

Question, where did you get the rods from?

[thesnoqualmieroute]

23 hours ago, Shiva said:

Question, where did you get the rods from?

I downloaded the .dat files from Breckland bricks and I had to use Bricklink's part editor to get them to the correct length, because the ones on Breckland's website don't actually go that big to accommodate 4 XXL driving wheels. I'm probably going to have to 3D print rods when I build 2678 because I don't think anyone sells rods that big.

[Shiva]

Ahh, cheers.

zephyr1934, does custom rods and is in the states.

[zephyr1934]

On 9/16/2024 at 1:53 PM, thesnoqualmieroute said:

I'm probably going to have to 3D print rods when I build 2678 because I don't think anyone sells rods that big.

 

On 9/16/2024 at 8:59 PM, Shiva said:

zephyr1934, does custom rods and is in the states.

Indeed, I've done out to 31.5 studs long rods. I don't think I got a picture of that one, but here's a 27 stud long rod

If you want to talk custom rods just drop me a comment on trainedbricks.com, just keep in mind that it could take several weeks to do a custom rod.

[thesnoqualmieroute]

9 minutes ago, zephyr1934 said:

 

Indeed, I've done out to 31.5 studs long rods. I don't think I got a picture of that one, but here's a 27 stud long rod

If you want to talk custom rods just drop me a comment on trainedbricks.com, just keep in mind that it could take several weeks to do a custom rod.

Oh wow! That would be amazing! Btw, I'm having some trouble downloading the digital resources from the trainedbricks website, is there another way you could provide them to me? Thanks so much!

[zephyr1934]

12 hours ago, thesnoqualmieroute said:

Oh wow! That would be amazing! Btw, I'm having some trouble downloading the digital resources from the trainedbricks website, is there another way you could provide them to me? Thanks so much!

The LDraw parts themselves are actually on brickshelf and can be found here. You will need to download the entire s-folder and the individual rods you want. All of the files are actually text files even though the extension is .dat. When you click on one of the .dat files in your browser it might display the text file rather than download it. That's fine, once open just save "the page" from your browser or copy/paste the text into a new text file. Just make sure you keep the original name including the .dat extension.

Then if you use Stud.io, see the installation instructions here.

[thesnoqualmieroute]

Hey all! I've been working on various things this past month, including acquiring the parts for #2678, finishing up valve gear, and designing a Northern Pacific class G-2 0-8-0 switcher, so I thought I might share an update with everyone.

Having finished the valve gear for #2678 and feeling satisfied with the build and its proportions enough to consider it complete, I ordered the parts for the physical build, and I hope to purchase the rods and boxpok drivers from Breckland Bricks soon. After surveying multiple power options and talking with a friend, I decided to try powering the build with Soundtraxx's Blunami system and switch over to 2 PF L motors, due to its reliability and ability to add sound and provide fine speed control. I will order the components after the parts for the boiler arrive so I can test fit the L motors in the drivetrain.

In addition, after a few weeks of procrastination, I finally finished up the plans for the valve gear, which surprisingly only took me around 15 minutes. Northern Pacific's A-4 class had Walschaert valve gear, and I did my best to model that to my best abilities in Lego form while keeping it completely functional. I built a mock up of the design, so it should work in theory on the real build. I plan to order to parts from Breckland Bricks as I really appreciate their selection in the coming days.

In addition to work on the A-4, I did some additional work designing a second locomotive, a Northern Pacific class G-2  0-8-0 switcher based off the USRA 0-8-0 switcher design and built in 1920 by the American Locomotive Company's Brooks Locomotive Works in Dunkirk, NY. I don't have as much research background with the G-2 class and it's not in a finished state so I don't feel comfortable posting it on it's own thread, but I'll still provide an update here. I started this design about a week ago and worked on it for a mere day, so it lacks the boiler hosing and other details, but I would still call it 75% complete. I plan to talk about the design process and history of the prototype in a separate post, but I'll still add a bit of information here. The boiler is a similar design to the A-4 and is 6 studs wide. It was a little hard in the beginning without the side air reservoir and compressor details to judge the correct height of the boiler, which I always find the hardest part of the modeling process. The tender is of similar construction to the G-2 class tenders used on #2678, and it features the same tiled walls of the tender to support the whole frame construction as the centepede tender. The trucks are of a simple bar and clip construction utilizing a minifigure handlebar for a majority of the detail, however, I may revise it as it might not match the level of detail as other comparable models. The overall width of the model is 9 wide, which I was surprised looks quite handsome with the smaller 6 wide boiler. One of my favorite details is the screw of the mechanical stroker which sticks out the back of the coal reservoir, as well as the switching style steps and coupler cut lever which give the model a very industrial feel.

To finish up the design, I am planning to finish up the valve gear and begin adding major piping details all over the model, however, I don't plan to put as much of a priority on this model as work builds up on the physical A-4 locomotive, and I finally start on my Z-8 challenger.

Lastly, I updated my North Coast Limited coaches from the original post to fit in better with the A-4, including switching them from 8-wide to 9-wide to match with the 9-wide A-4. In addition, I modernized the trucks with more detail and managed to make them thinner, as I didn't like how they stuck out from under the carbodies of the streamlined cars in the previous variation. Most importantly, I finally sat down and put away my procrastination to finish up a proper rounded-end observation car which certainly took a couple attempts, but I am really happy with the end result, and I think will be structurally stable in addition to looking good.

Once again, you can find more updates and photos on my Instagram @thesnoqualmieroute as well as more WIP's. Thanks again for your time and attention!

[Jeffinslaw]

Looking forward to seeing the Z8! I went through and redid my version a few months ago. I have the parts sitting in a bag... haven't had a chance to build it yet.

Edited October 8, 2024 by Jeffinslaw

[Feuer Zug]

Both locomotives appear to be gorgeous builds. The level of detail on both appear to be quite good. I can't wait to see the real versions.