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  • The First Turbo SD: Part 2

    by George Melvin

    ATSF SD24 4508 shows off a fresh application of the yellow Warbonnet paint in this well-lit view at Argentine Yard on June 3, 1973. The MU boxes on the pilot have been modified, and this view shows the bit of sheet-metal overhang to either side of the walkover step on the pilot. Units in the second delivery have an upturned piece in this area. Decals: Microscale 87-29.
    Model Railroading - October 2004 - Page 20

    The Santa Fe (ATSF) Railroad had experience with high-horsepower six-axle road switchers. A decade before the SD24 came along they had bought seven Baldwin centercab transfer units. In 1951-53, they bought 63 1,600-hp Alco RSD-4 and RSD-5 units, owning over a fourth of all those two models built. In 1954-55, the ATSF bought 12 of the total of 17 RSD-7s built. These units packed 2,400 hp from the Alco 244 power plant and predated the introduction of the SD24 by five years. Despite the lack of interest in six-axle EMD road switchers, Santa Fe tonnage was moved primarily with EMD power.

    Like three of the four roads that bought the SD24, the road owned a fleet of EMD FT's. In fact, at 320 units, they owned nearly one third of all FT's built. This group of units was between 15 and 20 years old as the EMD 1959 models came on the scene, so the road was poised to add new power in significant numbers. The decision was made to invest in more heavy duty six-axles when the SD24 came along, but the roads purchasing dollar was divided with Alco as that firm was offering the 2,400-hp RSD-15 with the new model 251 power plant at the same time. One month before the SD24 began arriving on the Santa Fe, the first of 24 of 50 RSD-15s came in April 1959. This group was completed in July and a second group of 26 came a year later, between April and June 1960.

    The first SD24s, an order of 45 units, were delivered in May and June 1959. They were painted in the then-current black livery with diagonal striping and lettering in silver, a small Santa Fe on the long hood and the famous circle-andcross herald that dated to 1901 was located on the side of the short hood. They were numbered 900-944. As with the RSD15s, they had low noses and were equipped with the 3,000-gallon fuel tank. Since the tank filled the space between the trucks, the air reservoirs were moved to the roof just forward of the exhaust stack. This feature disguised the fact that the long hood was somewhat lower than the short hood (on high nose models) and cab. This became a major spotting feature of the SD24 as only the single Kennecott Copper unit was fitted with a smaller tank and carried the air reservoir under the frame.

    EMD had lagged behind a bit on the low-nose option and GP20s and SD24s were built in both styles in accordance with the wishes of the individual railroad ordering the units. As with all other SD24s, the ATSF units also had the dynamicbrake option. A second group was built between May and July 1960 and numbered 945-979. These units arrived in the new dark blue with yellow trim and the billboard Santa Fe on the long hood. This scheme was initiated on the Santa Fe GP20's that started arriving in May 1960, concurrent with the second order of SD24's. Adding the fleet of 75 GP20's with the 80 SD24's, the Santa Fe owned 155 of the total production of 484 for the two turbocharged models offered in 1959!

    ATSF SD24 4546 is an early unit in the second delivery. The sun angle clearly shows the upturned sheet metal on the front edge of the walkway. Also note that the side lettering is slightly forward compared to the earlier units; the S falls ahead of a door seam compared to ending right at the door edge on the earlier units repainted from the black-and-silver scheme. Denver, CO; August 30, 1971. Decals: Microscale 87-12.
    Model Railroading - October 2004 - Page 21

    At least four of the original black group received a billboard Santa Fe on the long hoods and within six years, they were all repainted in the blue and yellow. In late 1969 and 1970, the group was renumbered from 900-979 to 4500-4579. In mid 1972, the fleet began receiving the new yellow Warbonnet scheme. As the line between Chicago and Kansas City was flatter, the GP20 fleet was assigned there and commonly seen in sets of four. West of Kansas City, the SD24 fleet shared honors as the new road power with the RSD-15's and could be seen in trios and quartets working over the mountains to California. After the purchase of the SD24's and RSD-15's, the Santa Fe never bought another Alco road unit, and six years passed before more SDs were added to the roster. The road acquired more four-axle EMD GP30's and GP35s during those years.

    In 1973, the road undertook a major rebuilding of the SD24 fleet. The SD26 upgrade program began at the roads San Bernardino, CA, shop in January 1973 and lasted for five years. Unit 4533 was the first unit done and returned to service as 4633; each unit received this number treatment, adding 100 to the renumbering done in 1969-70. The upgrade included new electrical equipment and a central air-filtration system, but the major component change was the replacement of the 16-cylinder 567 with a then-current 16-cylinder 645 engine, introduced in 1965. This brought the horsepower to 2,625, thus the SD26 model designation. Several visible charges marked the rebuild, the most notable being the relocation of the four air tanks, placing one pair astride the dynamic-brake fan and the other pair astride the cooling fans. This allowed the forward roof area to be raised to house the central air system. Unlike other rebuilt units on the Santa Fe, none of the SD26 received new-style cabs with angled roofs. After the first year, units rebuilt received a rooftop air conditioner; 29 units did not receive this feature. Later in the program, the new air filtration system used eliminated the original blower bulge.

    ATSF SD26 4605 was rebuilt in September 1974. One of ten units equipped with hump control to work the Argentine and Barstow yards, it is shown with one of the three slugs rebuilt from Union Pacific SD24 booster units. This unit has a different-style air conditioner than unit 4600. This high angle view shows the taper of the hood extension behind the cab and the round corner on the rear of the extension. Note that on unit 4600 and 4605, the striping from the wraparound herald on the nose extends right to the end of the hood rather than stopping short as shown on unit 4508 also pictured. This unit became Springfield Terminal 619 and was one of three left in service in 2004. Barstow, CA; February 17, 1985. Decals: Microscale 87-29.
    Model Railroading - October 2004 - Page 22 Model Railroading - October 2004 - Page 23

    Though not part of the rebuild program, the one-piece windshield was replaced with new sheet metal and a pair of windshields starting soon after the rebuilding was complete. The units were returned to the freight pool after rebuilding but were not kept in sets as they had been some of the time in the early years of service. Other uses required additional equipment. Ten units were fitted with Locotrol equipment for use on trains with unmanned mid-train power on unit trains, and another ten received hump control equipment for use in the hump yards in Kansas City and Barstow, CA.

    It is remarkable, considering the high mileage mainline years, that only one unit was retired after major wreck damage. Unit 4625 was retired after a wreck at Rustler Springs, TX, in August 1974, 15 months after its rebuilding. The entire remaining 79 units were disposed of in two groups. In the spring of 1985, 44 units were traded to EMD on an order for GP50s and were scrapped. Late in 1986, the remaining 35 units were retired and sold to Guilford Transportation Industries where they were lettered for Springfield Terminal. More about this group in a future issue.

    Next month, we will continue with the smallest group of SD24s, the 16 units owned by the Burlington.

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