Union Pacific's Final Four

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UP's Last Four SD40-2s

This page was last updated on May 17, 2024.

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Overview

Union Pacific SD40-2s 3805-3808 were different from the hundreds of other SD40s operated by UP. After much discussion among certain die-hard UP diesel researchers, with some input from both current and former EMD and UP employees who were there, here is the story...

In November 1980, Union Pacific accepted delivery of four special SD40-2 locomotives from their builder, Electro Motive Division of General Motors. These four locomotives were part of test by UP and EMD for the builder to build an improved SD40-2 for UP. UP 3805-3808 were originally part of EMD order 796345 for 40 units to be numbered as UP 3769-3808, but were changed before their construction to become a special four-unit separate order, 806053.

For a brief time in late 1980, and during the tests during 1981, EMD used SD40-2S (for "Special") for these four locomotives. After the one-year test, both EMD and UP referred to them as standard SD40-2s.

These four locomotives were regular SD40-2s with larger (longer) radiators and two-speed radiator cooling fans. In regular service, outside of a test, any additional horsepower would need a larger alternator, and EMD's AR10 alternator was at it limits in the SD40-2 at 3,000 horsepower.

Improved Engines

During the tests, all four units were initially equipped with improved engines rated at 3,300 horsepower. The increased horsepower came from adjusting the diesel engine's governor to allow higher engine speed of 950 rpm, with a fuel rack setting of 0.94. The four locomotives also had an improved turbocharger and improved intercoolers, which increased air flow and cooling to the engines themselves. These features were later included in EMD's SD50 and SD60 locomotives.

During stand-alone tests of the improved engine at EMD's LaGrange plant, these modifications resulted in the diesel engines running hot. The purpose of the test was to run modified locomotives in regular road service, with changes to the radiators to fix the problem of the diesel engines running too hot.

If these had not been special test applications, EMD would have given an improved or modified engine a different designation. They would have to, in order to keep track of the improvements and prevent mismatched parts. The only difference would have been the governor. In regular service, "strengthened" blocks would have required a new designation, say, 645F (which was used later) or 645E4, or 645E3C or 645E7 (the marine version of the 645) or 645D or even 645G.

Traction Motors

The four locomotives were equipped with EMD's standard D77 traction motors, not the later D77B or D77X3B motors that were installed on UP's 6900 series DDA40X units. If the production verions of these four locomotives had been rated at 3,300 hp, they would also probably have to have a better traction motor than the D77 or D77B. The D77X3B used on the 6900s were a special design because they were pouring 3,300 hp into four traction motors.

Longer Radiators

These four units had larger radiators (an extra standard radiator core, at 27-1/2 inches long) and two-speed radiator fans.

The carbodies on these four locomotive are longer than a standard SD40-2, by 28 inches, to accommodate the longer radiators. The long-hood end was fitted with eight doors under radiator section, rather than seven, and a shorter rear platform.

In late August 2000, a UP employee inspected UP 3808, and within a month had a chance to inspect UP 3804 and 3807. The only two items separating these units from any of the other SD40-2s are the two-speed cooling fans and the longer radiator cores. These locomotives have an extra 27-1/2 inch radiator core segment on each side. The cores are not taller or thicker than standard SD40-2 cores. In fact, the extra segment is just a standard SD40-2 single-length core segment.

Radiator cores are manufactured in segments, which are noted by length. These segments can be bolted together to achieve the desired length. EMD and outside vendors make these generally in 27-1/2 inch and 55 inch lengths. Radiator cooling capacity depends on a number of factors that affect the amount of surface area for heat exchange. Thus, the length, height and thickness of the cores are the controlling factors. In most cases, adding a segment or two to the basic core is how EMD added cooling capacity, along with the capacity and the number of fans. Thus, the only difference between the cooling system on a GP38-2 and an SD40-2 is the number of radiator segments and fans. The fans and the segments are the same on each; the 40-2 has one more fan and two more segments (one on each side) than the 38-2.

Two-Speed Radiator Fans

Wiring diagrams for the four locomotives, examined during late 2000, show that the four units retained the two-speed radiator fans from the one-year test period. Two-speed radiator fans were formally introduced by EMD on its SD50 locomotives and were an innovation at the time. Two-speed fans were intended to save a fuel (however small the amount), save wear and tear on the fans, and help maintain a more stable water temperature.

The two-speed fan design was to help with fuel conservation by reducing the parasitic load on the diesel engine, and also to increase the life of the fans by reducing the workload on them. The later electronic fan controller that was retrofitted by UP on many locomotives in place of the old temperature switches on the water manifold helps this even more, since it varies the operation of the fans. With the old temperature switches, the No. 1 fan was always the first one to turn on and the last one to shut off, so it always wore out or failed before the other two did. The electronic fan controller varies this, to even out the wear on the fans, so the No. 3 fan might come on first for a while or the No. 2, rather than the No. 1. And it always runs the fans at low speed until the engine temp requires it to speed up one or more fans to full speed.

After The Test

The tests lasted only one year, after which all four units were returned, at EMD's expense, to standard SD40-2 configuration, except for the longer radiators and extra length in their carbodies. A retired test engineer at UP told researchers that since EMD paid for the test program, UP does not have any mechanical department records, other than correspondence between EMD and UP setting up the special one-year test, and these documents were only found on archived microfilm.

At the end of the one-year test, and like the previous SD40-2s before them, UP 3805-3808 were later equipped with EMD's 645E3B engine, the same as the previous units delivered before them (UP 3574-3583 and 3609-3804). Comments about them being equipped with "strengthened" engines indicates that these four units were EMD's test of what would later become its 645F engine, which included a improved crankcase and better oil circulation for better engine cooling, as well as a stronger upper engine block. Although the EMD 645F only designates an improved crankcase, the same improved upper engine block was introduced on the SD50/60 series and is usually referred to as the "heavy block." The same 645F heavy block engine is today the standard replacement for all EMD 645 engines.

Not Super Series

Contrary to previously published reports, these four units were *not* equipped with EMD's "Super Series" wheelslip control. During a period of research from June through November 2000, looking for applicable documents among the records in Union Pacific's mechanical department, no mention was found of these four units being unique in any way.

As background, EMD's Super Series was introduced in June 1975 on two Clinchfield SD45s, 3619 and 3621. By late 1977 EMD formerly introduced Super Series locomotives with the test bed SD45X units, and on the six GP40X units for UP, numbered as UP 9000-9005. In April 1978, EMD built four SD40-2 locomotives for BN, numbered as BN 7049-7053, as the first production six-axle locomotives to have the Super Series installed. These four units, built under EMD order number 776083, had all six traction motors wired in parallel, which required the new higher output AR16 alternator, and used conventional SD40-2 car bodies. In September 1979, EMD built four SD40X locomotives for KCS, numbered as KCS 700-703. These four KCS locomotives were essentially an SD50 carbody on an SD40-2 frame, and had 3500 horsepower with the Super Series wheel control system, and were equipped with the larger AR16 alternator. In December 1980, EMD built six SD50S units for N&W, numbered as N&W 6500-6505. These four N&W units were equipped with 3500 horsepower, AR16 alternators, and Super Series wheel control, with a near exact SD50 car body on a SD40-2 frame.

In late 2000, the EMD parts books still showed the SD40-2SS as a specific model (for Super Series wheel slip-equipped units). A review of the EMD parts books do not show any specific parts for an SD40-2SS except for the main alternator. There is nothing in available EMD documents, or UP documents that indicates UP 3804-3808 were delivered as anything other than standard SD40-2s with a different cooling system. The wiring diagrams do not show any kind of upgraded wheelslip system ever having been aboard these units, nor do they show that the locomotives had an upgraded alternator.

EMD used SD40-2S for these four locomotive, for SD40-2 "Special" as the model designation on its own internal engineering documents. Throughout the test period, and for all the years after, UP only used the standard SD40-2 designation.

After The Test

This test may have been the precursor to an order UP had for an additional 120 SD40-2's (3809-3928) for delivery in the first three quarters of 1981. Eighty of these were canceled in early 1981; the remaining 40 were canceled in June 1981. By this time in early and mid 1981, due to a severe downturn in rail traffic, Union Pacific was beginning to put hundreds of locomotives in storage for lack of business.

EMD built the first SD50 locomotives in December 1980. UP tested two new N&W SD50S-designated models (N&W 6500 and 6501) in April 1981, but with over 600 units in storage by late 1982, UP waited to buy the new model until 1984.

Research has not yet found how these four units for UP relate to the SD40X locomotives built for KCS in 1975, or the SD50S locomotives built for N&W in late 1980, or the special SD40-2s built for BN in 1978. As a visual indicator, the KCS SD50S units had the newer angled blower ducts as used on production SD50 units, along with two-speed radiator fans and wheel slip control. The shop superintendent at BN's Alliance, Nebraska, shops informed researchers that the BN units had the strengthened engine blocks but apparently did not have the two-speed radiator fans.

Any EMD records concerning this apparent test program may have existed for a period of time, but have long since disappeared into the company archives as EMD moved into production of the SD70 series locomotives in 1992. Those company archives may or may not have survived the sale of EMD to Caterpillar in 2010.

The 1986 EMD Product Reference book, which supposedly shows all EMD locomotives in service at the time, showed UP 3805-3808 as order number 806053 and wiring diagram WD01190, compared to UP 3769-3804 with order number 796345 and wiring diagram WD01050. After being examined by a UP employee, the only difference in wiring diagrams was found to be the two-speed fans, with no mention of wheel slip controls or anything else not on the other 36 units in the original group (UP 3769-3808).

The UP locomotive diagram book from 1982 shows UP 3769-3808 on the same page, starting with the initial date of May 1980 (Sheet L-56-13, original date of 5-29-80). Later revisions ( Rev. C, 1-85, Rev. D, 6-85, Rev. E, 12-86, and Rev. F, 9-94) make no mention of anything different among any of the 40 units in the last group.

Current Status

Road
Number		 Builder
Date		 Builder
Number		 Date
Retired		 Renumbered
To		 Date
Renumbered		 Notes
UP 3805 Nov 1980 806053-1 29 Nov 2001     1
UP 3806 Nov 1980 806053-2   UP 3412 (2nd) 3 Nov 2003 2
UP 3807 Nov 1980 806053-3   UP 3277 (2nd) 23 Jun 2004 3
UP 3808 Nov 1980 806053-4 30 Jan 2002     4

General Notes:

  1. UP 3805-3808 were built as test units and were equipped with a improved engines and turbochargers, longer radiators, two-speed radiator fans, as a test for EMD to increase cooling capacity for its SD40-2 model. At the conclusion of the one-year test, all four units were equipped with standard engines and standard turbochargers.
  2. The carbodies are longer than a standard SD40-2 by approximately 28 inches to accommodate longer radiators; each long-hood is fitted with eight doors under radiator section, rather than seven, and a shorter rear platform.
  3. Previously reported as being equipped with improved wheel-slip control (a feature of the later Super Series units). Research in the railroad's mechanical department records completed during 2000 found that these units were not equipped with the Super Series improved wheel slip control features.
  4. Fitted with 88-inch nose and corrugated radiator screens.

Notes:

  1. UP 3805 was retired by UP on November 29, 2001; sold to GE for lease to Iowa, Chicago & Eastern (ICE) 6406 in January 2003; ICE merged along with Dakota, Minnesota & Eastern Railroad into Canadian Pacific in September 2008.
  2. UP 3806 was renumbered to UP 3412 (2nd) in November 2003 to clear the 3800 series for use by new SD70M units; renumbered to UP 1924 in November 2014; rebuilt to UPY SD40N 3005 in June 2015 and paired with yard slug UPY 3006; renumbered to UPY 300 and UPY 400 in June 2019.
  3. UP 3807 was renumbered to UP 3277 (2nd) in June 2004 to clear the 3800 series for use by new SD70M units; rebuilt to SD40N 1946 in October 2016.
  4. UP 3808 was retired by UP on January 30, 2002; sold to Evansville & Western Railway 6003 (EVWR started operations on January 1, 2006, operating over 124 miles of former L&N trackage between Evansville on the Ohio River, and Okawville, Indiana.)

Sources

Sources include correspondence during June through November 2000 between Don Strack, Bill Metzger, George Poindexter, and other individuals who were employees of Union Pacific, and who prefer to remain unnamed.

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