David Lotz updated June 29, 2012


David Lotz's Tags


Browse Articles » How-To Text View Magazine View

  • Southern Pacific's SD-7's

    By Peter Arnold

    SD-7 #1404 at Bakersfield, Ca. on October 12,1974.

    SP 1425 at Tucson, Arizona on December 16, 1977. This is one of the two units to receive a full length red stripe along the running board #1411 is the other unit so painted.

    SP 2742 at San Jose, California on June 11, 1972. This unit was maintained at San Jose and served as back-up commuter power. Its steam generator was kept in working order for this assignment.
    Prototype Modeler - February 1981 - Page 14 width= Prototype Modeler - February 1981 - Page 15 width=

       Espee received 43 SD7's numbered 5279-5293 and 5308-5335 from November of 1952 to September of 1953. They were intended for branchline service such as the Northwestern Pacific and for heavy switching at yards such as Roseville, Taylor in Los Angeles, and at Tucson. Twenty-one of them (5308, 5316-5335) came equipped with steam generators for use on local passenger trains. These passenger units are easily spotted, even today, as they have dual underbody tanks. The rear tank holds 1,200 gallons of fuel while the forward tank was used for 1,200 gallons of boiler water. The units without steam generators have a large gap between the fuel tank and the air reservoirs.

       This forward tank was converted to carry additional fuel when the passenger units were removed from passenger service, most by 1960. The 2742 was kept in stand-by commute service in San Jose into the 1970s. The passenger units had the large "can" signal lights applied to both ends; whereas the other units had one "can" signal light on the short hood only. Number 5308 was the exception as it was the ex-EMD demo 990 and was equipped with a steam generator and only one signal light. It was also the only Southern Pacific SD7 that had a winterization hatch and dual controls.

       All of the SD7s came from the factory painted black with silver ends, orange tiger stripes, and orange lettering. Most of the SD7s were repainted into the "Black Widow" colors between 1954 and 1960. Beginning in 1960, the grey and scarlet scheme became the standard; and all the SD7s eventually received this paint scheme. The system renumbering in 1965 put the SD7s into the 2700-2742 number block. They retained these numbers until 1974 when they were renumbered into the 1400-1442 block to make room for additional switchers in the 2700s. In early 1979, Espee began to send their twenty six year old SD7s through their Sacramento shops for complete rebuilding. They are being renumbered into the 1500 series as they emerge from the shops. Besides having all of their components totally rebuilt, they are receiving the full SP lighting package on both ends (as are all SP and SSW units that are rebuilt or bought new). These renewed SD7s should see many more years of service. Espee's SD7s are classed as switchers and are currently assigned to the yards in the Los Angeles area, where they perform heavy switching and transfer work. They are also used at the Espee's yards in Tucson, Arizona, Roseville, California, Sparks, Nevada, and Lompoc, California. For additional information and photos of Espee's SD7s, consult the SP Motive Power Annuals and the SP Review.

    SP 1517 at West Colton, California on February 23, 1980. Note the full light package on the rear.

    SP 1517 again at West Colton, has been in service for only one month since its total rebuild at SP's Sacramento shops.
    Prototype Modeler - February 1981 - Page 16 width=


       The Athearn SD9 is the starting point to build the almost identical SD7. I chose to build this particular unit because of its unusually small fuel tank. Before starting to work, it is absolutely necessary to have photos of the particular unit that you wish to model, and have photos taken at a specific time in its life. SP's SD7s have had four sets of numbers, had three different paint schemes, and gone through a total rebuilding. During their twenty-eight years of service, many details such as lights, horns, radio antennas and steam generators have been changed; so a photo of the particular unit that you wish to model at a specific time period is necessary.

    Taylor Yard in May, 1976. Note the conduit to the radio antenna.

    Also in Taylor Yard. Note the circular radio antenna used for the yard channel.
    Prototype Modeler - February 1981 - Page 17 width=

       It is best to start with an undecorated model; but if yours is already painted, you must remove the old paint completely before starting your work. Scalecoat makes a good product for this purpose. Next, the unwanted detail has to be removed. Use a No. 17 X-Acto knife, file and fine sandpaper to remove the following (being careful not to remove surrounding detail): front and rear headlights, drop step brackets, MU receptacles and plates, roof top lift rings, vents, and radio antenna from the top of the short hood, air horn mounting hole, cast-on grab irons, and front and rear ladders (if you desire).

       The forward fuel tank should also be removed if you are modeling one of the freight-only units. I removed mine with a hack saw and file. The rear set of engine-room louvers on both sides should be carefully removed. This set should really be placed with the other three sets that are located under the dynamic brake blister, but I chose not to worry about this minor discrepancy.

    In Taylor Yard, LA on April 8, 1973. SD7's are used in pairs to switch the yard.

    Two SD- 7's, #5288 and 5289, were ballasted with 15 extra tons and assigned to helper duties over Cuesta from San Luis Obispo to Santa Margarita, Ca. when photographed in early 1953 at San Luis Obispo. Photo by Art Laidlaw; Collection of Peter Arnold.

    The colors of 5288 are a black body with silver ends and orange stripes and lettering. Photo by Art Laidlaw; Collection of Peter Arnold
    Prototype Modeler - February 1981 - Page 18 width= Prototype Modeler - February 1981 - Page 19 width=

    Its steam generator inactive for years, #2727 formerly a passenger SD-7, was photographed in the Santa Fe's Hobart Yard on December 8, 1973.
    Prototype Modeler - February 1981 - Page 20 width=

    Peter Arnold's model of #2714 captures the prototype while being a relatively easy conversion from a standard Athearn unit. Photos by Charles Williams
    Prototype Modeler - February 1981 - Page 21 width=

       The forward notch above the fuel tanks on both sides should be filled in with body putty. Also, if you are replacing the Athearn horn, its mounting hole should be filled in with putty. The hollow portion of the air reservoirs should be filled in with putty to make them round on all sides as they will be exposed when the forward fuel tank is removed.

       Besides the rear louvers, the other two external differences between the SD7 and SD9 are the marker lights and the steps. The SD9 has its marker lights mounted toward the corner of the unit; whereas the SD7 has its located almost centered above the number boards. Fortunately for the SD7 modeler, Athearn has located its markers slightly in from the corner - about halfway between where they should be for either model. I chose to leave them in their present location, and drilled them to accept jewels. The SD7's markers are also mounted on rectangular panels. I simulated these by scribing lines around the markers in the proper locations by referring to photographs. The steps on the SD9 are fabricated in a stair-step shape; whereas the SD7 has its steps fashioned in a vertical ladder shape. This can be simulated on the Athearn model by shaving the second step so that it is even with the third one.


      Color Scalecoat Floquil
      SP Grey 28 132
      SP Scarlet 29 136
      Black 10 10
      SP Daylight Orange 30 134
      SP Daylight Red 31 135
      Silver (Aluminum) 47 100

       I used .019" brass wire with Kemtron stanchions for the handrails. Follow the contours of the Athearn handrails, except around the steps. Study the photos to determine the new contour of the handrails. A new hole should be drilled near the top of the steps for the handrail. A second piece of brass wire should be soldered to the first piece to extend down to the bottom hole near the steps. This should be done at all four corners. Use .015" brass wire for the long end grab, above the Detail Associates formed coupler lift bar. You should now add all of the detail parts according to the photographs - horn, sun shades, drop steps, MU receptacles, headlights, signal light, grabirons, lift rings, MU air hoses, radio antenna, vents, and ladders if you choose to add them.

        Mount the air reservoirs on the frame, and use .019" brass wire to form the air lines according to the photos. I drilled two holes in the frame where the forward fuel tank was to accept two short pieces of .019" wire. On these I mounted one Kemtron rerail frog on each side. Kadee couplers were installed.

       Before painting, throughly wash the whole model and allow to dry. Both Scalecoat and Floquil offer appropriate Southern Pacific paints. I chose to paint my model with Scalecoat's SP Grey and SP Scarlet. You may wish to paint your model in one of the ther schemes; either black with aluminum ends, orange tiger stripes, and orange bettering or the "Black Widow" scheme that was black with Aluminum ends, Aluminum lettering, and Daylight Orange and Daylight Red stripes. I used Micro-Scale decals, but there are others available. Micro-Scale also offers a set to do the tiger stripe scheme. I found it easier to paint and decal the number boards before placing them on the model. After wiping the decal residue off the model with a damp cloth, I sprayed the entire model with McClosky's Semi Gloss Finish (a varnish used for furniture). I have found it to be far superior to any product in the model field. It is also available in four varieties of glossiness, and it has proven to be very durable. I lightly weathered my model with Floquil earth colors. Jewels are now added for markers and lights, and your SD7 is ready to go to work.



      Qty Unit Mfg Part No.


      1 ea Athearn   Powered SD9
      1 pr Kadee   Couplers
          Detail Associates DA 2505 .015" Brass Wire
          Detail Associates DA 2506 .019" Brass Wire
      1 set Kemtron 788 Handrail Stanchions
      1 set Cal-Scale 277 Brass Air Hose
      1 pkg Detail Associates DA 1508 MU Air Hoses
      1 pkg Detail Associates DA 1401 Drop Step - Early
      1 ea Details West DW 108 Signal Light
        or Detail Associates DA 1002 Oscillating Headlights
        and Detail Associates DA 1001 Oscillating Headlights
      1 pkg Detail Associates DA 1507 MU Receptacles and Plates
      1 pkg Detail Associates DA 1601 Nathan 3 -Chime Air Horn
        or Detail Associates DA 1603 Nathan P-Series Air Horn
      1 pkg Detail Associates DA 1802 Radio Antenna
      1 pkg Detail Associates DA 1901 Air Vent
      1 pkg Detail Associates DA 2201 Grabirons and NBW
      1 pkg Detail Associates DA 1301 Cab Sunshades
      1 pkg Detail Associates DA 1101 Lift Rings
        or Detail Associates DA 2206 Eye Bolts
      1 pkg Detail Associates DA 2204 Coupler Lift Bar and Brackets
      1 pr Kemtron 160 Rerail Frog
      1 pkg Detail Associates DA 2207 SD7/9 Ladders (optional)
      1 pkg Detail Associates DA 1703 Classification Light Jewel
        set Micro-Scale 11 Espee (Red/Grey)
        or Micro-Scale 71 Espee (Tiger Stripes)
        or Micro-Scale 201 Espee (Black Widow)

    Article Details

    • Original Author Peter Arnold
    • Source Prototype Modeler
    • Publication Date February 1981

    Article Album (1 photo)

    Share - Report