California's Railroad to the U.S. 1861 - 1996

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Model Train Help EBook

Baldwin S-12 Summary

Additions welcome. Other List Subjects also solicited.

This information was offered, in response to Athearn about to release their HO Scale Baldwin S-12 in SP Tiger Stripe paint. I have also assimilated information from previous posts to the List regarding the S-12.


  • Arved Grass
  • Don Jewel
  • Ernie Fisch
  • Nelson Kennedy
  • Tony Johnson
  • Tony Thompson
  • Richard Percy

see also Baldwin Summary for details of other Baldwin switchers.


There were four classes of S-12's on the SP, classes DS-110, (T&NO DS-112), DS-114, and DS-118. In 1965 SP changed its class system, and these became classified BS412-1 through BS412-4. Since the units are basically the same within the individual classes, we will use the original classification of these locomotives for reference. Note that some details, such as moving the numberboards around, adding radios, and blanking off the small number indicator on the hood were done on a 'random' basis.

There were some earlier questions about these units we'd like to clear up. Except for the comments about the Athearn model, This is going to be 'old hat' for those of you with the '83-85 SP Review. The front of the cab has only two windows facing forward on either side of the hood. There are no windows above the hood. While in later in life, the number boards were moved close to the cab to obstruct this, DS-110 was delivered with the numberboards well forward on the hood (about 1/3 back from the front radiators).

#1456 was the first to be shipped with B-L-H builders plates, all previous in this class (DS-110) had the older Baldwin builders plate.

Class DS-110, and T&NO class DS-112 did not have the 'washer/dryer' headlights. Louvered door arrangement varied from class to class, and maybe even during the life of the individual unit. This warrants further research, and until more can be learned, the modeler is advised to seek photos (preferably of both sides taken at or near the same timeframe) of specific locomotives he's modeling. The 1970 SP Annual states the louvered doors were on S-12's until mid '52, but caution is still advised. DS-112 also lacks the numberboards, has an extended stack, and has the thicker welded frame with the notch for the fuel filler.

Looking at photo's in the relevant SP Annuals, the lefthand side of the unit could have one or two hood doors with full length louvers, and the righthand side could have none or one hood door with louvers. The Athearn model has one louvered door each side.

Class DS-110 is unique in that it has a thinner frame edge that doesn't require the notch for the fuel filler. Earlier (S-10) and later orders had thicker frames requiring the notch. DS-110 also has 'full length' radiators on both sides (viewed from the front, similar to the S-10), while the DS-112 and later have a grate (or door) at the bottom of the left hand side (right hand when viewing model from front) of the radiator, as on the Athearn model.

DS-114 was the first class with the 'washer/dryer' headlight. Otherwise, they were similar to the three DS-112 units. They don't appear to have been delivered with numberboards, but they might have received them fairly early. The pictures of 1499 show that it doesn't have the numberboard in it's photo dated 4/57, but 1506 does in it's photo dated 5/54.

DS-118 was the last class of S-12's. These units had MU, oval stacks, outside handrails, and a cast equipment trust plate. The MU looks identical to the layout on other Baldwins on the SP, with the MU connectors arranged vertically along the center, with two drop steps on either side, just as on the cover of the '83-85 Annual. There's a LOT of detail there. The stack is similar to the Athearn model, except that I think it's supposed to be taller. There is one picture of the cab end (1540 on page 24 of the '83-85 review), and it looks identical to the Athearn model, so it's likely safe to say that the Athearn model is accurate for this class with the exception of lacking the 'washer/dryer' headlight. The step arrangement behind the cab is probably unique to this order, due to the platform needed for the MU and drop step arrangement, but will need confirming with photos of other classes of S-12s taken from the rear (cab) end. DS-118's don't look to have numberboards when delivered. The builder's photo of 1540 doesn't show numberboards. It's hard to see, but they don't appear evident on 1541, either.

DS-110 were delivered between 1/23/51 and 4/24/51 and assigned numbers 1442-1463. During the 1965 renumbering, they became class BS412-1, and numbered 2100-2120. 1447 didn't survive long enough to be renumbered, as it was sold for scrap to Purdy Metals in Oakland, CA in 11/63.

DS-112s were purchased for the T&NO, delivered in 1/52, and numbered 105-7. In the 1965 renumbering, they became class BS412-2, number 2121-2123.

DS-114s were delivered between 11/52 and 3/53 and numbered 1492-1513. 1498 & 1505 became T&NO 121 & 122 in 1956. In the 1965 renumbering, the T&NO units became 2124 & 2125, and the rest became 2126-2145 these became class BS412-3.

DS-118s were delivered between 10/53 and 11/53, and numbered 1539-1550. In the 1965 renumbering, they became 2146-2157 these became class BS412-4.

In relation to the Microscale decal sheet 87-71

1. There are several types of slogan:

  • Watch Your Step (white on clear)
  • Think Safety Always (white on clear)
  • Always be Careful (black on clear) I guess for orange pilots
  • Look and Live (black on clear)
  • There are four of each slogan on the sheet.
  • Would there be four per loco and would all four on a loco be the same?

2. When did the slogans first get applied to the locos?

All S-12's were delivered in the Tiger Stripe scheme, BTW. Of the photos in the annual, the front pilot has 'Watch Your Step' (white on clear) on the left side (right when viewed from the front) and 'Always Be Careful' on the right (left when viewed from the front). There are a lot of exceptions, though. 1506 has 'Look and Live' on the left front, 122 has 'Always Be Careful' in the same position. Perhaps someone can fill this in a bit better. There are some pretty early photos showing this lettering, so if they weren't delivered this way, they must have been repainted very soon with the logos.

In relation to marker lights or classification lights: Try Precision Scale 3314? Hard to judge size from the Walther's catalogue, but the shape is right.

In reference to grab iron 'ladders': all units appear to have a three grab irons next to the cab on the righthand side of the hood. Later in their life, some units received three grabs on the lefthand side. None of the photo's of units appearing in the 1970 SP Annual have the left side grabs

The '83-85 Review shows 1444, with left side grab irons in a company photo taken in central California in _1953_. So if your time frame matches, at least one unit in this class already had the grab irons installed. As near as I can tell, all the photos of S-12s in the '83-85 Review show these grab irons. I don't have the '70 Motive Power Annual handy to refer to, though. As always, it's best to model from photos of specific units.

From the '83-85 review:

  • 1444 taken in 'central California about 1953.' It shows grab irons up the side of the locomotive.
  • 2121 in 12/68 does not have fireman's side grabs. It has a rotary beacon and extended stack, though (extended stack was uncommon for Pacific Line's units). This unit was still in tiger stripe, but obviously renumbered.
  • 1499 photographed 4/57 and 1506 photographed 1/53 have the area in the shade, so it's hard to tell, but they don't look to have them.
  • 122 photographed 11/63 doesn't have them (Tiger stripe).
  • 2126 photographed in 7/69 had them (red and grey).
  • Builders photo of 1541 (taken 9/53) doesn't have them.
  • Photo of 1540 taken 5/53 has the area blocked by the cab.
  • 1545 had the grabs when photographed in 10/65 (red and grey, but not yet renumbered).
  • 2157 had the grabs when photographed 6/74 (red and grey).
  • 2146 had the grabs when photographed 11/66 (red and grey).


All were all delivered in the orange and black paint scheme with the tiger stripes. The only pre-1965 changes was the elimination of the tiger stripes on the air tanks on some of the units, as it was just too much trouble to mask the tanks for painting.

SP simplified the Orange/ Black paint scheme about 1956, dropping the tiger stripes in favor of solid Orange ends and frame stripe, this is better known as the 'Halloween' paint scheme. Some S-12's received this variation before the Scarlet/Grey was adopted in 1958.

The last S-12's in service according to the 83-85 SP Review were 2150 (ex 1543) and 2157 (ex 1550), 2157 was 'the' last one retired Aug. 1974. Both of these are now at the Orange Empire Museum at Perris California.

OAL over CouplersOAL over PilotsTruck CentersTruck Wheelbase
Prototype46 ft42 ft ½in22 ft 8 in8 ft
HO Scale161 mm147 mm79 mm28 mm
Athearn-147 mm76.5 mm28 mm

Baldwin Reference Books:

  • Diesels From Eddystone
  • Diesel Builders, Vol. 3
  • SP Motive Power Annual 1970 - Built by Baldwin article.
  • SP Motive Power Review 1983-85 - SP Baldwin Diesels, The S-12's page 18.
  • SP Dieselization by John Bonds Garmany.

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