"Rugged Little Beasts"

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Union Pacific's SW10 switchers, 1980-1999

This page was last updated on November 10, 2021.

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The Need

By the mid to late 1970s UP's switcher fleet had become very old by railroad standards, with the newest units, the 1953-built SW9s, being twenty years old. The in-service fleet was composed of NW2s, SW7s, SW9s and TR5s, all built between 1939 and 1953. It was apparent that either more low-horsepower road power, or new switch engines would soon be needed, or the old switchers would have to be remanufactured. Whichever path was chosen, the UP knew action would have to be taken to reduce the costs of failures and maintenance attributed to the old switchers.

One of the directions taken during Frank D. Acord's tenure as UP's motive power chief from October 1971 until his retirement in June 1980, was to simplify the railroad's locomotive roster. That roster, all purchased while David S. Neuhart was General Superintendent of the railroad's Motive Power and Machinery Department from April 1949 to September 1971, included many "odd" and one-of-a-kind types of units, including the turbines, the 6900 class Centennials, and other double diesels. Frank Acord wanted to get the roster down to just a few standard models of locomotives. Another goal was to modernize the fleet. The motive power studies of the 1970s showed that UP still needed locomotives of the SW-type configuration, mostly for the urban yards and other industrialized locations. The railroad also wanted to reduce its numbers of four-axle locomotives and began a program to abandon branchlines and upgrade other branches to allow use of SD, six-axle locomotives.

The form that the new switcher would take would be determined by five choices. First, the railroad could buy new locomotives, but at the time the builders were busy with C30-7s and SD40-2s, and the price paid for new switchers would be a premium one. Second, they could buy locomotives off of the used locomotive market, but that market was tight and expensive, and the available switchers were mostly the same type and age as the railroad's current fleet which they wanted to replace. Third, they could rebuild the units they needed themselves, from the fleet that they already owned. Fourth, the railroad could have its fleet rebuilt by an outside vendor, but the rebuild market hadn't yet reached the size and strength that it would later. Or fifth, they could do nothing, and delay the decision to a later time. Union Pacific chose to do a combination of the second and fifth choices, and rebuild their own, but only in small lots to spread out the cost.

The SW10 Arrives

The motive power study completed in 1978 showed that Union Pacific needed a fleet of about sixty dedicated yard switchers. After considering its possible options, Union Pacific chose to rebuild the sixty-five remaining early EMD switchers (twenty-two SW7s, thirty-six SW9s and seven TR5As) into a new switcher model, later designated as the SW10. (The program was first referred to simply as the SW7/9 upgrade, with the decision to call them SW10s coming in about September 1979.)

These three models, the SW7, SW9, and TR5A, were selected for the rebuild program since all were similar in most details, and were powered with 567B and BC engines which could economically be overhauled and upgraded to 12-645C engines using new 645 power assemblies. The forty-eight remaining NW2s (as of June 1978, of an original fleet of ninety-six units) were rejected for the rebuild program due to their significantly different equipment arrangement, and because their 12-cylinder 567A engine blocks would have required expensive modifications to accommodate the upgrade to 645 power assemblies. On a personal note, this author, while a journeyman mechanic for UP at Salt Lake shops, submitted a suggestion in June 1978 that would upgrade the SW7 and SW9 fleet with EMD model 645 engines, and electric radiator fans to replace the troublesome belt-driven radiator fans. It is unknown if his suggestion was accepted -- it was not acknowledged -- but during August 1978 the railroad's Mechanical Department began the development work on what would become the SW10.

Included in the 1978 study was final survey of the then-available commercial switchers. In mid 1978, two Missouri Pacific MP15DCs were borrowed to compare the cost-effectiveness of the proposed switcher rebuild program versus the purchase of new switchers. The two units were used in the combined Omaha/Council Bluffs terminal area. The data from the tests did not support a change in plans; the modest increase in performance offered by the MP15DCs did not warrant their substantially higher price.

The SW10 rebuild program included 645-power assemblies in place of the original 567-assemblies. Also included were all new cabling and wiring, and updated electrical gear, which included a couple module cards with some solid state circuitry. A new consolidated equipment rack for the water tank, oil filters, and other mechanical components was built using parts from retired GP9s. A new radiator section using twin 36-inch electrically-powered cooling fans, also taken from retired GP9s, was installed to replace the inefficient and expensive to maintain belt-driven 54-inch fan that originally equipped these units. The new design also included a large sandbox occupying the front of the unit in place of the original radiator fan intake and radiator shutter assembly. This new, external sand box design did away with the two original, internal sand boxes, with their four difficult-to-access sand traps. The cab interior layout and design also received attention. The new design included a modern control stand, electric cab heating, an electric refrigerator, and other features to bring it up to the FRA-mandated "clean cab" standards. Also as part of the rebuild program, the original friction bearing trucks were converted to roller bearings. The finished, operating weight for the SW10s was 251,200 pounds.

UP SW9 1848, retired in August 1978, was chosen to be the first SW10. It was reinstated to the roster and work began converting it to UP's first SW10 in October 1978 at UP's shops in Omaha, Nebraska. UP 1848 emerged as the first example of the new switcher on August 2, 1979. After qualification and acceptance by the Operating Department, the unit was assigned (along with rebuilt 1839) to Portland, Oregon in January 1980. UP 1848 was renumbered to UP 1200 on March 13, 1980, while assigned to Albina Yard in Portland, Oregon, following the decision that the SW10s differed enough from the SW7s and SW9s to warrant their own number series. Only two other SW10s, 1839 and 1866, carried their old SW9 road numbers after being rebuilt. Retired during May 1978, the 1839 was also formally reinstated to the roster and rebuilt as the second SW10, using its old 1839 road number, being released on November 14, 1979. It was renumbered to UP 1201 on April 1, 1980, while at Omaha for wreck repairs. UP 1866 was completed as the third SW10, with a completion date of January 25, 1980 and renumbered to UP 1202 before entering service, very soon after January 29, 1980, the date of a recently discovered slide. All subsequent SW10s were given a 1200-series number upon completion, starting with UP 1203, completed on March 9, 1980.

The original 1980 program called for fifteen units to be rebuilt. A follow-on program for 1981 was for fifteen more units, which included the first rebuild of one of UP's seven remaining TR5As, 1874. Also in 1981, UP 1205 was involved in a wreck in Portland and returned to Omaha for repairs. SW7 1812 was in Omaha shop being stripped for repairs, having been the first SW7 selected for the upgrade program, but its cab was used to repair the 1205 instead. The now completely stripped frame of 1812 was later scrapped by UP. Up until mid 1981, all SW10s had been rebuilt from SW9s. While SW7 1812 was being stripped in preparation for entrance into the rebuild program, UP found that some of the component mounting dimensions differed between the SW7 and the SW9. The needed engineering changes were accomplished for SW7s to be rebuilt to SW10s, and 1817 was selected as the first SW7 to become an SW10, completed as 1231 in February 1982.

UP 1202 was wrecked in early October 1982, while assigned to Portland, Oregon. After being sent to Salt Lake shops for evaluation, the unit was shipped on a flat car to Omaha shops for repair of the wreck damage. While awaiting repairs, its Diesel engine was used in the completion of SW10 1246, with 1202 getting another prime mover prior to re-entering service.

After the program had progressed for about a year and a half, UP's operating unions approached the railroad with several changes in the SW10 cab layout and design. These changes (a total of eighteen) were first applied to 1231 in May 1982, and included a relocated and improved control stand, a front-opening Igloo-brand electric refrigerator, new beige and brown cab interior colors, and the relocation of the handbrake, changed from the original wheel style inside the cab to the smaller ratchet style outside the cab. At about the same time, the addition of multiple unit (MU) connections front and rear were made a part of the rebuilding program, although no unit-to-unit MU walkway was provided. These MU connections were added to the SW10s to allow their use in train consists under power as they were moved between their assigned yards and the shops where they received regular maintenance. The modified 1231 was presented to the operating unions at Salt Lake City in mid May 1982, and after formal acceptance, the changes were incorporated into the SW10 program. These changes were retro-fitted to all earlier SW10s as they came due for major inspections.

As each SW10 was completed by Omaha shop, it was operated in a stationary load test to ensure a successful rebuild. After load-testing, the units were painted, with each unit entering service towards the end of the month (for budgeting reasons). Following formal qualification and acceptance by the Operating Department, the units would then be assigned to local Omaha/Council Bluffs service to allow a supervised break-in period, then assigned to western locations to enter full service. Some of the early assignments included 1201-1212 at Portland's Albina Yard, 1213 at Provo, Utah, and 1214 and 1215 at Pocatello, Idaho. UP 1224 went first to Las Vegas and 1226 was initially assigned to Los Angeles.

The SW10 program came to an end in December 1984, with the conversion of nine ex-Missouri Pacific SW9s and four Western Pacific SW9s. The last former UP unit completed as an SW10 was 1265, rebuilt from SW9 1838 in September 1984. The previous four were rebuilt from ex-MP SW9s 1243-1245. The five units following 1265 also came from ex-MP SW9s. The last four SW10s completed were rebuilt from ex-WP SW9s. Right from the time of the merger in late 1982, the former Western Pacific fleet of six SW9s were considered to be potential candidates for the SW10 program. At the time they were the only ex-WP units to be considered as having a place in the post-merger roster. With the completion of UP 1274 (ex-WP SW9 606) on the second to last day of 1984, December 30th, the SW10 rebuild program ended. Although thirty-two additional ex-MP SW9s were available for rebuild, along with the entire 141-unit fleet of ex-MP SW1200s, Union Pacific, possibly because of the post merger Missouri Pacific influence, chose to acquire additional switchers through the December 1984 purchase of fifteen second hand MP15DCs from Pittsburgh and Lake Erie. These post-merger switcher philosophies would be covered in later article about the late EMD switchers of UP.

A look at switcher assignments on Union Pacific in March 1982 shows the two newest SW10s, 1229 and 1230, assigned to Omaha for their break-in period. The just-completed UP 1231 and 1232 were still in the Omaha paint shop awaiting their release for service. Both the Wyoming and Kansas Divisions were devoid of assigned SW10s. UP 1200-1209 and 1211 were assigned to the Oregon Division, with 1203, 1206, 1208, and 1211 working in Seattle at Argo Yard. The other seven units were working in Portland's Albina Yard. UP 1210 was working at Pocatello and 1214 was at Idaho Falls, both on the Idaho Division. Of the operating fleet of thirty-one units, the remaining sixteen units (UP 1212, 1213, 1215-1228) were all assigned to the California Division; UP 1216 and 1217 were at Ogden, Utah, UP 1213, 1215, and 1219 were at Salt Lake City, 1218 was at Provo, 1224 was at Las Vegas, 1225 was at Yermo, and 1212, 1220-1223, 1226-1228 were at Los Angeles.

Locomotive assignments during October 1990, when 41 GP38-2s were re-assigned from road service to switching service, show UP 1200-1239 assigned to Salt Lake City and west; 1240-1259 assigned to North Platte and east and south; 1260-1265 assigned to trim switching at Kansas City, Missouri; and 1267-1273 assigned to the Port Terminal Railroad Association at Houston, Texas.

The 40 SW10s assigned to Salt Lake City and west included 12 units (1200-1211) assigned directly to the Salt Lake City shop and yard. UP 1212 was assigned to the new yard at Elko, Nevada, and UP 1213-1215 were assigned to the former WP yard at Stockton, California. SW10s 1216 and 1217 were at Ogden (along with GP15-1s 1580-1583), and 1218 was at Provo, with 1219 at Las Vegas. Los Angeles was the home for 10 SW10s, 1220-1229. In Idaho, UP 1230-1233 were assigned to trim service at Pocatello's hump yard; 1234 was at Nampa, and 1235 was at La Grande in Oregon. UP 1236 was on the Camas Prairie at Lewiston, Idaho. The last three SW10s in this forty-unit group were assigned to the shop at Albina Yard in Portland, Oregon. These three units were used in "shop-swap" service to relieve the 1300-series MP15DCs as these newer units were out of service for regular maintenance and inspections.

In January 1993, UP 1243 was changed from switch service to passenger service and retained as part of historical locomotive collection at Cheyenne, Wyoming.

Locomotive assignments for September 1994 showed the remaining 66 SW10s assigned to points throughout the UP system. Fourteen were assigned to Salt Lake City, 12 were assigned to Los Angeles. Fifteen were assigned to points in Texas, with six at Fort Worth, seven at Houston, one at Longview, and another at Arlington. Seven SW10s were assigned to Council Bluffs, and five were assigned at Stockton, California. Four were at North Platte and three were at Ogden. Single unit assignments include one each at Provo, Albina, Seattle, Cheyenne (1243), North Little Rock, and at Tioga, near Alexandria, Louisiana.

Assignments during early 1995 included: UP 1200-1218 at Salt Lake City; 1219, 1220 at Pocatello, Idaho; 1221-1225 at Stockton, California; 1226 at Hinkle; 1227-1242 at Los Angeles; 1243 at Cheyenne; 1244, 1246-1249 at Albina; 1250-1261 at North Platte; and 1263-1273 at Houston. UP 1245 and 1262 are not shown. (information taken from Model Railroading, March 1995, page 4, Letter to the Editor from G. S. "Steve" Fuchs, Salt Lake City, Utah)

With 61 units still on roster, as of mid 1996, there were still 14 SW10s assigned to Salt Lake City. Eight units each were assigned to Los Angeles, Houston, and the Council Bluffs/Omaha area. Seven were assigned to the former C&NW yard at Proviso, Illinois, four were at Stockton, and three at both North Platte and Albina. Two SW10s were now working at Provo, Utah, and single units were at Cheyenne (1243) and St. Louis (1272). Two others were in ex-C&NW territory - UP 1204 was at Butler, Wis., and 1247 was working at Global Two, C&NW's Chicago intermodal terminal.

UP's SW10s were also used in local service in Utah. One report from 1994 stated that UP's Marblehead Local, based in Salt Lake City and serving former Western Pacific branches south of Great Salt Lake, used UP 1202 and 1215 as the local's power. There is a photo by Joel Thompson on November 7, 1997 showing three SW10s (UP 1213, 1225, 1284) on UP's Tintic Local, switching a large limestone quarry at Keigley on the former D&RGW Tintic Branch southwest of Provo, Utah.


As of early 1995, nine SW10s of the fleet of 75 had left the roster. As already mentioned, SW10 1205 was wrecked in mid 1981, but the damage (a crushed cab) was repaired in July 1981 by using the cab from retired SW7 1817. If the damage had occurred three or four years later, the unit may have been retired rather than repaired, because of the availability of sufficient numbers of units in the fleet of late EMD switchers. The first SW10 to be formally retired, UP 1245 was involved in a wreck on March 4, 1987 at North Platte, Nebraska. The wreck was a collision with a cut of standing cars which resulted in a cracked frame for the 1245. The unit was retired three days later and sent to Omaha for disposition. Disposal consisted of the unit being stripped of usable components for use on other SW10s, and any of the road's other locomotives, including use of the 1245's long hood to repair the wreck damage on another SW10. The frame and cab of the 1245 was loaded onto a flat car and sold for scrap on March 29, 1988 to Aaron Ferer and Sons, whose salvage yard was located adjacent to UP's Omaha shop complex.

The second and third units set aside (UP 1266 and 1274) were both retired on the same day, February 6, 1990. A fourth unit, UP 1271, was retired on June 5, 1991. These three SW10s were sold in October 1991. UP 1266 was sold to VMV Enterprises at Paducah, Kentucky. At last report the unit was still there. UP 1274 was sold to the South East Kansas Railroad, and 1271 was sold to Western Railway Supply (WRS) of Fontana, California. WRS resold 1271 to Peoria Locomotive Works in Peoria, Illinois, who sold it to the Peoria and Pekin Union 701 in late January 1993.

The only SW10 retired in 1991 was the 1237, which was retired on August 12, 1991 and sold to VMV Enterprises in Paducah, Kentucky on December 9, 1991.

Two SW10s were retired in 1992. UP 1216 was retired on April 28, 1992 and sold to Pielet Brothers on March 17, 1993. Instead of their usual scrapping, Pielet resold it to National Railway Equipment at Dixmoor, Illinois in July 1993. The second SW10 retired in 1992 was UP 1267. It was retired on August 20, 1992 after suffering a fire in early 1992 that damaged its cab while leased to the Port Terminal Railroad Association (PTRA) in Houston, Texas. The unit was returned to UP by PTRA on April 9, 1992. UP sold the 1267 to National Railway Equipment at Dixmoor, Illinois on March 31, 1993. The former UP 1267 was seen at Canadian Pacific's Agincourt shop in Toronto during late July 1993, and was later in service for the Roanoke Valley Co-Generation Project at Weldon, North Carolina.

The two SW10 retirements in 1993 were both because of wreck damage. UP 1224 was retired on September 24, 1993 and was stored awaiting disposition at Jenks shop in North Little Rock, Arkansas. UP 1209 was wrecked on December 3, 1993 at Salt Lake City, Utah in a side-swipe collision. The unit was declared unrepairable and was scrapped by UP's shop forces at Salt Lake City, and the stripped frame loaded onto a flatcar during April 1994. The unit was formally retired in April 1994. On May 14, 1996, five more SW10s (1203, 1208, 1227, 1258, 1264) were retired. All had been removed from service due to mechanical failure and stored at Salt Lake City for the past six months.

The SW10s had several limitations that prevent their more wide spread use, including their truck design. The SW10s all had a bone-jarring ride, and had speed restrictions due to the unsprung trucks. They were hard on the track, they derail easily and were difficult to rerail due to their drop equalizers. Those equalizers also make it hard to change the inside brake shoes. Many of the engine crews preferred the quieter and easier ride of the MP15DCs. But the SW10s were reliable, easy and cheap to maintain, and, as one motive power official put it, were "rugged little beasts".

By early 1995, Union Pacific's fleet of SW10s had about reached the end of their service life. The units had been in service for between 10 years and almost 15 years, and many of the prime mover engine blocks were mostly over 40 years old, and many were due for scheduled overhaul. The truck frames were showing signs of fatigue and were cracking due to age and stress. The on-going exercise of cost analysis showed that time had passed them by, and it made more economic sense to buy or lease newer power than to sink the very large sums of money needed to again rebuild the SW10 fleet. Also, getting them off the roster meant an end to that type of truck design, with the attendant reduction of parts inventories. Their service application was also limited to the close-in urban areas. The large fleet of ex-MP MP15DCs were all equipped with road trucks for higher speeds, and were also equipped with toilets, so these newer units could be used in road and local service. The SW10s were also limited by their low operating weight and their low, 1,200 horsepower. When the design was finalized in 1978, the designers did not foresee that rail cars were getting heavier and that switching chores would need more muscle. Weight was held down due to some of the locations that UP's switchers were required to operate in, but most of those locations no longer exist. The low weight and horsepower today works against the SW10 and it was common to see consists of two, three and even four units coupled together to get the job done.

In summary, the 75-unit fleet of Union Pacific SW10s had served the railroad well in the time since they first came onto the rails beginning in 1979. The changes brought on by the 1982 merger had caught up with these units, and their limitations were becoming more apparent. The motive power practices of the railroad had changed, and many on the railroad see no place for these unique locomotives. As they come due for major repairs, or as their suffer from wreck damage, the units had been and would continue to be retired. Only the growth in traffic in the last few years had saved the fleet this long. The 1992 acquisition of 32 second-hand MP15ACs was meant to allow the replacement of all SW10s, but the little units were too badly needed to handle the suddenly increasing switching chores systemwide. During late 1994, the stated intent was that should more MP15ACs become available at a good price, this could spell the real final call for another, and possibly the last, unique-to-UP locomotive design. Changes from the C&NW and SP mergers of 1995 and 1996 have changed the railroad's motive power needs, including an influx of former C&NW and SP SW1500s, sealing the SW10s' fate of retirement as soon as possible.

During July 1998, UP retired the last remaining 44 SW10s. These little 1200 horsepower workhorses served UP well, from their initial construction in 1980 to 1982, but had been found to be underpowered and too light for the switching UP was then doing. Although the last SW10 was officially retired on 15 July 1998, several apparently continued operating for as long as another two weeks. The remaining units were sold in July 1998, many as part of three large groups. Ten units were sold to Connell Finance and 16 units were sold to the David J. Joseph Co., the largest metal salvage dealer in the nation, and some of those had been resold. The third group of SW10s, 15 units, were sold to Ferrocarril Mexicano (FerroMex), the successful bidder for the concession to operate the former FNM Ferrocarril del Pacifico. Only UP 96 (ex-UP 1243) remains in service, as part of the historical collection, assigned to passenger service at Cheyenne, Wyoming.

Roster Listing

Final roster of UP's SW10s -- A full roster listing of all of UP's SW10 locomotives.