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| Sunset Models, ex-Arizona Eastern Mk-4 as SP 3237. |
In December 2022, I bought the Sunset Arizona Eastern Mk-4 that I did the paint work on by 2017 as SP 3237. At this point the engine isn't weathered at all, it will need weight in the boiler, a decoder installed at some point, and some other basics like lighting, and a crew, etc.
History & Photos of SP 3237
The engine was built as Arizona Eastern 901 in July 1913 and put into service two months later. I should point out again here that the AE's Mk-4s were not the same in overall mechanical specifications as the "Pacific Lines" Mk-4s, such as my SP 3203 model. The AE engines were about 12" shorter in the frame, with different domes, air pump positions, square cabs until the end. They did share the 57" drivers, as the Pacific Lines engines had. They also were within about Why they weren't slotted into another open class, like Mk-3 or above as Mk-7, which wasn't used at the time, is an open question. Mk-3 might have been a temporary experimental class, which SP assigned, but never used or never built.
The Arizona Eastern was absorbed into the SP system and repainted in November 1924 to SP standards as SP 3237. The boiler was upgraded to 210PSI December 7, 1926 at Phoenix, AZ. Another rebuild completed March 24, 1939 reduced the cylinders diameter to 23-1/2". The SP 3237's end came on June 7, 1953 at Tracy, being pulled out of service. She was sold to scrap at West Oakland on July 9, 1953. As I plan to model pretty much flexible dates from circa 1946-1954 with various engines, so the 3237 will be mostly for the excursion passenger train to Owenyo and the freight service circa 1950 when the ETT authorized certain Mk-2/4s and specifically by engine number until 1953 when it was retired.
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| Steam-cleaned SP 3237 and 3266 pulling the fan trip to Owenyo at Searles, 5-30-52 - Carl Blaubach photo - Brian Black Collection |
The special doubleheader out of Mojave shows off for the cameras at Searles Station, the interchange point with the Trona Railway. If I decide to run an excursion to Owenyo on my Jawbone Branch, the 3237 will probably be assigned along with the 3266. At the time of this photo, SP 3237 only has about 13 months left before retirement.
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| SP 3237 Bartlett on the Jawbone branch, circa-1950-1954. - Leo Barusch photo - Dani Collection |
There are also several photos of SP 3237 in Tom Dill's SP San Joaquin Valley Line book, which I don't have permission to post here. One shows SP 3237 switching at Lone Pine on a frosty morning, the other shot shows the SP 3237 pulling the Owenyo Local south of Little Lake. Both photos are mis-captioned as SP 3227, but digitally zooming in on the photos clearly shows the engine with a small sand dome (distinctive of the AE Mk-4s) and in one shot the train indicator and number board under the headlight with a "3" as the third number.
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| A very dirty SP 3237, unsure of the date, as the 3237 didn't make it past mid-1953. - Eddie Sims collection |
These prototype photos clearly show the engine was fitted in later life with a smoke deflector/splitter. The excursion photo and the Eddie Sims collection shot show the engine with pilot-beam mounted fire-hose box and equipment. This was probably a very good idea to have when the engine was the only steam engine within 25-100 miles, so any fire that was started, the engine would have to help put out.
The Sunset Models Mk-4 Engine (AE Version)
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| Left side of unpainted (stock brass paint finish) Sunset Model. |
The stock model has fairly good details, including the bell rope. The left side isn't exactly correct, as the prototype SP 3237 only has one air compressor on the left side with the running board stepping up over it. I'm not sure I'll get into brass-bashing the engine that far right now, as that will require a large amount of work on the boiler and even the etched modeling of the jacketing on the left side of the boiler, which is above my pay-grade on a brass model at this stage.
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| Right side of unpainted (stock brass paint finish) Sunset Model. |
The right side valve piston-valve hanger ended up coming un-soldered (probably a cold-joint during construction). So I had to re-solder that part of the engine.
The AE engines had the early standard steel cab design, not the later "Sport" type cab. The "Spot cabs" were distinctive of many SP Pacific Lines standard engines starting in the 1920s, with the Mt-3-class engines. Some engines of the Mk-2/4/5/6 classes were also rebuilt with new cabs, which allowed the replacing of stay-bolts without removing the cab. The early square cabs however required the cab's removal to fully do regular shopping and servicing of the stay-bolts around the rear of the firebox.
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| Model painted, decalled, tender swapped but no other modifications yet. |
The slightly earlier tender was swapped out with a spare Sunset 120-C-1/2 class tender from Sunsets' 1990s production run of F-3/4/5 class 2-10-2s. I've worked with these tenders before with my F-class engines and I like them, as they are very solid construction and good in operations.
Physical Changes to Model
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| Brass stack deflector from rebuild of SP 3266. |
The basic Sunset Models AE Mk-4 has boiler-tube pilot and a straight stack. I may decide at some point to deal with the pilot. However, for the foreseeable future, I probably will rebuild the deflector stack before finishing the engine for service on the Jawbone Branch, like I did on the SP 3266.
I don't know that I'll go to all the trouble of removing one of the left side air pumps, adding a box over with end sheets around the remaining air pump, adding rear air tank under the left running board, and rebuilding the radiator piping to match photo. This would require major rebuilding of the engine's left side. I also don't have any handy right side photos of the engine during this time, so there's a limit to how far I'm willing to push a brass-bashing project like this.
In Closing
I plan to use older ESU Lok 3.5 decoders in the bottom of the boiler with 100Ohm Bass-Reflex speakers from Railmaster Hobbies mounted in the smokebox, which should allow the engine to be mechanically balanced over the drivers when weighted. Note that ESU LokSound decoders now use the 8 Ohm speakers, so I'm specifically using the older 100-Ohm speakers for the old ESU 3.5 decoders. If you want to use 'modern' decoders, then probably be looking for the 8-ohm speaker version.
Ideally, this Mk-4 will be able to pull prototypical length trains of 12-15 cars around my layout up 1.25% grade into Owenyo from the Mojave staging yard below.
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| Track plan for Jawbone Branch in March 2024. |
Jason Hill
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