Union Pacific Steam Locomotives - General Notes

This page was last updated on January 31, 2023.

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Belpaire Fireboxes

The Belpaire Firebox had a rectangular cross section and greater volume and heat absorbing area than did a radial stay firebox with the same grate area. Consequently it could produce 10 to 20 percent more steam at the same firing rate. The Pennsylvania had the largest number of such engines, followed by the Canadian National and the Great Northern. (Robert A. LeMassena, 2001)

The Belpaire firebox was invented by Alfred Jules Belpaire in 1860 for the Belgian State Railways to allow use of Belgium's poor grade of coal.

Union Pacific used Belpaire fireboxes on just six 4-6-0s built by Rhode Island for OSL&UN in 1891, and on eight 4-8-0s built by Brooks for UP in 1899. Below are their number series:

Type Quantity Builder Date
OSL&UN 1459-1464 4-6-0 6 Rhode Island 1891 OSL 611-616; OSL 1508-1513
UP 1500-1507 4-8-0 8 Brooks 1899 UP 1800-1807

Big Boy Tenders

Concerning the "builder photo" of UP 4022. This image has been included in many, many books. For years, it was believed that this was the official builders photo of the second series of UP Big Boys (Class 4-8-8-4-2). But there was the nagging problem with the tender. If the second series Big Boys had tenders of the same design as the late Challengers (25-C-200 and 25-C-300), then why was the top row of rivets on the coal bunker not up along the top, but down lower (mid cab window level) like the first series tenders (25-C-100)?

(View the photo of UP 4022)

Several historians of Union Pacific steam locomotives concluded that Alco had created an impostor for its builder's card of UP 4022. This is actually the builders photo of 4002 with a neat bit of photo editing to create the 4022. Note that there is no number board on the rails between the two axles of the leading truck as seen in true Alco builders photos (it's there in the builder photo of 4002). This explains the 25-C-100 series tender behind the 4022. Why were there no official builders photos of the second series Big Boys taken at the plant? There must be a good story here yet to be discovered.

An examination of a photo of UP 4024 confirmed that, when delivered, it had a 25-C-400 tender, with a high rivet line, just like the late Challengers.

As you look through the photos of Big Boys, the high rivet line on the coal bunker and the "plain" flat plates behind the steps are easy spotting features of the -400 series tenders. You will also see that there were many tender swaps post 1950. This is especially true from 1955 and beyond.

Here is a list of museum Big Boys and the tender class on display; number taken from each tender's builder plate.

25-C Tender Classes

Below is a list of the tenders assigned to the UP Big Boys at the end of their service lives. The list was created in about 1961-1962 as the tenders were separated from the locomotives, prior to the locomotives being scrapped. Locomotives that were donated or preserved, or held out-of-service after mid 1962 are not shown. UP 4003 and 4010 were scrapped in mid 1963 with their tenders attached.

Class 25-C (25,000 gallons; cylindrical) -- 7 tenders

Fuel Removed
Date Locomotive
Date Tender
25-C-101 1941 coal UP 4000 4884-1 4-8-8-4 Aug 1961 Jul 1962
25-C-102 1941 coal UP 4001 4884-1 4-8-8-4 Nov 1961 Feb 1962
25-C-108 1941 coal UP 4007 4884-1 4-8-8-4 Aug 1961 Jan 1962
25-C-109 1941 coal UP 4008 4884-1 4-8-8-4 Jan 1962 Jul 1962
25-C-116 1941 coal UP 4015 4884-1 4-8-8-4 Aug 1961 Dec 1961
25-C-103 1941 coal UP 4019 4884-1 4-8-8-4 Jan 1962 Feb 1962
25-C-403 1937? coal UP 4022 4884-2 4-8-8-4 Feb 1962 Jul 1962

(View a list of all 25-C tenders separated from Big Boys and Challengers)

(View a roster listing of all 25 UP Big Boys)

Classes and Class Designations

On Union Pacific, there were two similar, but different series of locomotive Classes, also known as Class Designations or Classifications.

Locomotive classes were shown in Union Pacific's internal documents, including UP's locomotive folio diagram sheets, various engineering drawings, and in the Accounting Department's Form 70 "List Of Agencies, Stations, Equipment, Etc."

Locomotive classes were also painted on the locomotive cab sides, beginning with the Harriman Common Standard era.

Prior to the Common Standard era, UP's locomotives were classed using a full description of the wheel arrangement and road numbers. Examples included the "900 and 1000 Class" for 4-6-0s, along with "10 Wheeled Engines 1400 Class 62 Inch Drivers" and for the 2-8-0 Consolidations, "Baldwin Compound Con. Engine No.'s 1622 To 1639."

Common Standard (CS) Class

The earliest locomotive classes were the CS, or Common Standard classes. These CS classes started in the Harriman Common Standard era, and were first shown on painting and lettering sheets dated 1904.

The CS classes included examples such as MK-1, MK-2, etc., and included the locomotive wheel arrangement (C for Consolidation, and MK for Mikado, etc.), with a sequential number. These designations were not used on the locomotive cab sides, but continued being used on engineering drawings into the 1940s, labeled as "Common Standard Class."

When referred to as the CS class, such as C-2, C-3, etc., it meant the class was the second and third variation of the 2-8-0 Consolidation class, built using Harriman-era Common Standard specifications.

These "CS" designations were not used prior to the Harriman Era (first locomotives delivered in 1904), and seldom used after the MK-10 2-8-2s were delivered in 1921.

The CS classes were used for the six wheel arrangements delivered through 1921. These included:

Name Wheel
CS Class
Atlantic 4-4-2 A-1 to A-4
Consolidation 2-8-0 C-1 to C-2
Mikado 2-8-2 MK-1 to MK-10
Pacific 4-6-2 P-1 to P-13
Switch 0-6-0 S-1 to S-6
Ten-Wheel 4-6-0 T-1 to T-3

The CS class was not applied to the locomotives themselves, but continued to be used into the 1940s on internal mechanical department documents, but only for those earliest classes built before 1921.

Cab Side Class

At the same time that the Common Standard (CS) class was adopted for locomotives in the 1900-1905 period, Union Pacific and its subsidiary railroads also began using a similar locomotive classification that included the wheel arrangement and the driver size. This has become known as the cab side class.

The cab side lettering included the locomotive wheel arrangement and driver size. An example would be the MK-57 (or the WWII era MacA-57) for the Common Standard MK-1 and MK-2 Mikado 2-8-2s.

This cab side class was shown in diagram books, and was painted on the locomotive cab side. Numerous photos of locomotives newly delivered after World War I show this cab side class of wheel arrangement and driver size.

The diagram books from as early as 1918, through to the last revisions in 1949, only use the cab side class of wheel arrangement and driver size.

Examples of later use of the cab side class would by TTT for Two-Ten-Two for the 2-10-2s, and FEF Four-Eight-Four for the 4-8-4 Northerns. Other examples would be SA-C for the 2-8-8-0s, meaning Simple Articulated Consolidation, and CSA for Challenger Simple Articulated for the earliest 4-6-6-4 Challengers.

Jim Ehernberger's excellent article in The Streamliner, Volume 8, Number 1 (1992), published by the Union Pacific Historical Society, discussed the cab side lettering after 1937.

Compound Locomotives

The following comes from George Drury's Guide to North American Steam Locomotives (Kalmbach, 1993)

In 1889 Samuel Vauclain of Baldwin Locomotive Works patented a four-cylinder compound system, and Baldwin built the first of the type, a 4-4-0 for the Baltimore & Ohio. The Vauclain compound had two cylinders on each side: a high-pressure cylinder and a low-pressure cylinder. Usually the small high-pressure cylinder was on top; on low-drivered freight locomotives the low-pressure cylinder was on top for clearance reasons. The diameter of the low-pressure cylinder was about 1.7 times that of the high-pressure cylinder. The two cylinders, a valve chamber, and half the cylinder saddle were cast in a single piece.

A single valve on each side fed steam from the boiler to the high-pressure cylinder and from there to the low-pressure cylinder. The two pistons drove on a common crosshead. The engine could be worked simple -- boiler pressure in all four cylinders -- for starting. On the whole the design was successful. By 1904, when it was superseded by the balanced compound, Baldwin had built more than 2,000 Vauclain compound locomotives.

Compound engines worked well in stationary power plants and in steamships, where triple-expansion engines were common and quintuple-expansion engines weren't unheard of. In these applications they were low-speed engines, and they ran better when the valves for each stage could be controlled independently -- and that task was easier for an engineer who was concerned only with running a stationary engine and did not have to watch for signals, curves, washouts, stations, and cows on the track.

One of the fundamental dilemmas in the design of a steam locomotive concerns the use of exhaust steam to create a draft for the fire. It does that by passing through a nozzle in the smokebox, working on the same principle as an atomizer or spray gun. The more restrictive the nozzle, the better the draft -- and the more back pressure in the cylinder. The greater the amount of energy used to create the draft, the less energy will be available to move the train.

Another problem is that of condensation. As steam expands in the cylinder, some of it condenses into water. If the cylinder is hot and the initial steam pressure is high, the problem is almost nonexistent, but if the cylinder is cold and the pressure is low, the water, being incompressible, can damage the piston and cylinder head.

The draft and condensation problems were worse on compound locomotives. By the time steam had pushed the high-pressure piston to the other end of the cylinder, passed through the valves and the pipes to the low-pressure cylinder, and pushed that piston the length of the cylinder, it had very little pressure but a great deal of volume. With little energy left in the steam, exhausting the cylinder took longer, and there was less energy available to create the required draft.

The superheater delivered the efficiency that compounding only promised. It was a simple, no-moving-parts affair, an arrangement of pipes in the smokebox that intercepted steam on its route from steam dome to cylinders and shuttled it back through the firetubes of the boiler, where it absorbed more heat and therefore more energy.

(Wikipedia article about Vauclain four-cylinder compound locomotives) (includes a link to the original June 1889 patent)

Schenectady Cross-Compound Locomotives

In 1898, Schenectady built the following two-cylinder cross-compound locomotives for Union Pacific; all were rebuilt on the dates shown:

Type Quantity Builder Date
Date Rebuilt
To Simple
UP 1320 (2nd), 1321 (2nd) 2-8-0 2 Schenectady 1898 1909 UP 119, 120

OSL Rebuilt Compound Locomotives

In 1901, OSL rebuilt two locomotives (likely at Pocatello) from simple to compound. Both were rebuilt as simple in 1907.

1901 OSL
Date Rebuilt
To Compound
Builder Date
Date Rebuilt
To Simple
OSL 670 OSL&UN 1450 OSL 628 1901 Rhode Island Jan 1891 OSL 684 1907 1
OSL 671 OSL&UN 1465 OSL 637 1901 Cooke Oct 1890 OSL 685 1907 2


As Built
Date To
Date To
  OSL 670 62-19x24 57-22&34x26 1901 57-19-1/2x26 1907
  OSL 671 62-19x24 57-14&24x26 1901 57-19-1/2x26 1907

OSL 670 was rebuilt using the Richmond compound design, and OSL 671 was rebuilt using the Baldwin Vauclain compound design.

Baldwin Compound Locomotives

Baldwin built the following Vauclain compound locomotives for Union Pacific (and its subsidiaries); all were rebuilt to simple on the dates shown:

Type Quantity Builder Date
Date Rebuilt
To Simple
UP 1621-1680 2-8-0 60 Baldwin 1900 1910-1912 UP 400-459
UP 1820-1869 4-6-0 50 Baldwin 1900, 1903 1912-1918 UP 1320-1369
UP 1680-1699 2-8-0 20 Baldwin 1901 1910-1912 UP 460-479
OSL 770-777 2-6-0 8 Baldwin 1901 1911-1913 OSL 4100-4107
OSL 950-964 2-8-0 15 Baldwin 1901 1911 OSL 510-524
ORR&N 400-405 4-6-0 5 Baldwin 1901 1923 (2) OWRR&N 1729-1732
ORR&N 300-314 2-8-0 15 Baldwin 1901, 1903 1910-1919 OWRR&N 710-724
UP 1508-1521 2-8-0 15 Baldwin 1902 1910-1912 UP 150-158, OWRR&N 725-729
OSL 800-809 4-6-0 10 Baldwin 1902 1906-1909 OSL 1562-1571
OSL 965-979 2-8-0 15 Baldwin 1903   OSL 525-539
UP 1901-1920 2-8-0 20 Baldwin 1903   UP 480-499
ORR&N 194-197 4-6-2 4 Baldwin 1905 1915-1921 OWRR&N 3200-3203
UP 21-35 4-4-2 15 Baldwin 1906 (not rebuilt) UP 3320-3334

Congdon Extensions and Smokestacks

Steam locomotives soon became well known for starting fires along the railroad lines. To prevent lineside fires caused by cinders exhausted from steam locomotive exhaust stacks, several designers attempted development of devices known as a front extension that would catch cinders. A front extension extended the cylinder exhaust ports in the lower part of the smokebox up to a height above the output ends of the flues. A netting was then installed at a level above the flues with the intent of catching cinders and ejecting them out of the smokebox and down a tube to the tracks.

Isaac H. Congdon patented his locomotive front extension in 1864 (U. S. Patent 43,898, dated August 23, 1864, "Spark Arrester" "Improvement to Locomotive-Engines"), while he was Master Mechanic of the Great Western Railroad (later Wabash). In 1866 Congdon was appointed as Union Pacific's first General Master Mechanic. The extension front end was installed to several Union Pacific locomotives in 1867, 1868, and 1869. They were in service until 1870. When C. G. Hammond became Union Pacific's General Superintendent, all of the Congdon front end extensions were removed and replaced by diamond smokestacks of the style used by CB&Q. (Locomotive Engineering, Volume 9, 1896, page 496, Google Books)

(C. G. Hammond was Union Pacific Superintendent until October 1870 when he was replaced by E. Sickles; by September 1874 Hammond was the Assistant President of The Pullman Company; see New York Times, October 7, 1870 and Official Railway Guide, September 1874, page xxxiii)

In March 1878 Congdon patented a brake shoe design that combined wrought iron and cast iron with the intent of creating a safer passenger car brake shoe. Although Congdon himself was not involved, a company by the name of Congdon Brake Shoe Company was organized to manufacture the brake shoes. The patent had been assigned to George Sargent and when the patent expired, Sargent changed the company to Sargent Brake Shoe Company.

There are at least fifteen other patents in Congdon's name, including one from 1884 that covered the design of another spark arrestor that, like the 1864 design, was mounted internally in an extended smokebox. In 1878 Congdon received a patent for the smokestack that was later made famous on Denver, South Park & Pacific locomotives. Under U. S. Patent 203,592, dated May 14, 1878, the design called for a large "Locomotive Smoke-Stack" with internal devices that kept sparks from being exhausted and causing fires, without affecting the draft of the exhaust, thereby reducing the efficiency of the boiler.

Photographic research by Dave Johnson suggests that the U&N Brooks 2-6-0s may have spent their whole careers with the Congdon stacks, but the Kansas Central locomotives had a diamond stack at the beginning and at the end. Around 1885-1886 the Union Pacific experimented with extended smokeboxes and capped stacks on at least three of the five Kansas Central Brooks 2-6-0 locomotives. Photos of the locomotives on other lines plus a description of the stacks lying behind the Leavenworth roundhouse in the standard gauge days seem to indicate a change back to the as-built set up by the late 1880s. The capped stacks were actually spark arrestors with a covered top and screened slits in the flange of the cap to allow the smoke out. Dave Johnson recalled that some of the early Colorado Central locomotives such as the Porters and possibly at least one of the Cooke 2-6-0 locomotives received the same set up for a short time.

Isaac H. Congdon, formerly superintendent of motive power and car departments of the Union Pacific, and inventor of the Congdon brake shoe, died at his home in Omaha, Nebraska on August 21, 1899 at the age of sixty-six years. He was born at Granville, Massachusetts on June 1, 1833, and entered railway service on July 11, 1851, as machinist with the Cleveland, Columbus & Cincinnati. He was afterward for one year machinist with Springfield Hartford & New Haven, but on August 1, 1853, returned to the Cleveland Columbus & Cincinnati as foreman of machine shops, which position he held until December 31, 1859. From January 1, 1860 to March 1866, he was master mechanic of the Great Western Railway at Springfield, Illinois, and in March 1866, went to the Union Pacific as general master mechanic. After holding the latter position for sixteen years, he was promoted to the position of superintendent of the motive power and car departments of the Union Pacific on September 1, 1882, which he resigned on December 1, 1885. (Railway Age, August 25, 1899)

Isaac Congdon retired in December 1885 while Charles Adams was president of Union Pacific, and was possibly asked to retire due to numerous organizational problems in Union Pacific's mechanical department. (Klein, Union Pacific, pages 498 and 526)

Date Vacated

The Union Pacific System used the term "vacated" when referring to the date a locomotive was dropped from the active roster for disposal, usually by scrapping by the railroad itself. In later years some locomotives were sold for scrap. If a locomotive was sold for further use, that term is shown and the new owner indicated, along with whatever information is known on the later history of the locomotive.

Headlights and Number Plates

"Electric headlights first came to the type in 1916 on the 1807 at Omaha. The acetylene lamps were used until the electric era. (Initial applications began ca. 1900 on passenger locomotives only)" (Kratville, Motive Power of the Union Pacific, page 40)

"New electric headlights were first applied to the locomotives beginning in Omaha in 1914." (Kratville, Motive Power of the Union Pacific, page 96)

The first UP steam engines with a centered headlight were 4-6-2 no. 2906 and 4-8-2 no. 7002 in 1936 when they were modernized with rollerbearings and other modern features. Prior to that time, all steam engines had their electric headlights mounted on top of the smokebox ahead of the exhaust stack. (Kratville, Motive Power of the Union Pacific, page 156)

"Headlights were mounted on the center of the smokebox door on all of the type during the 1938-1941 face-lifting of Jabelmann." (Kratville, Motive Power of the Union Pacific, page 99)

"Just prior to World War II, Otto Jabelmann instigated a complete motive power rebuilding program. All types of locomotives were included in this general upgrading. Most mainline power acquired Master Mechanics front ends, headlights were lowered to the center of the smokebox face, heralds were stricken from tenders and a new lettering scheme introduced." (Kratville, Motive Power of the Union Pacific, page 10)

"Round front number plates were replaced by rectangular plates affixed to centered headlights when the latter were finally moved to the smoke box door after 1934." (Gordon McCulloch)

Locomotive Dates

The dates in many published lists of Union Pacific steam locomotives can be wrong in many cases. Research in the railroad's own records, and in the records of the builders themselves indicates that the dates that Union Pacific used in its records were the date when that particular locomotive left Omaha for the first time - the locomotive's in-service date. Whereas the builders used a similar date for their own records that was when the locomotive was completed, or in some cases, when it was delivered.

To confuse the situation more, the dates in most steam locomotive lists are for the first locomotive of a group to be completed, or delivered, or its in-service date. Later locomotives that followed in the group could have dates weeks, or one or two months after the first locomotive. The best source for an accurate date is the builder plate on the locomotive itself, but actual checks of steam locomotive builder plates are very rare.

For Union Pacific's steam locomotives, research in the available documents indicates that the majority of locomotives beginning with Harriman orders of the 1905-1910 period, were shipped dead in train because they were not ready for service, and lacked so many appliances that the railroad opted to supply and install themselves in Omaha or some other major shop. This included bolt-on items such as injectors, air pumps, bells, whistles, headlights and turbo generators. This remained as the standard operating practice for many years. Research suggests that this practice ended in the mid 1930s with the early Fetterman CSA 4-6-6-4 Challengers. This change in the practice of the railroad applying many of its own appliances was part of the larger change that came in the 1936-1937 period of single-system management of the railroad.

Although it was originally compiled to answer many questions about dates as they apply to diesel locomotives, the following collection of frequently asked questions (FAQ) flows nicely into steam rosters as well.

(Read the LocoNotes FAQ about Dates)

Locomotive Weights

Steam locomotives were classified by their ability to pull trains, meaning that the weight on their drivers was directly related to their tractive power. Their weight-on-drivers was almost always recorded and shown as part of their basic description, along with total engine weight. As Union Pacific and its subsidiaries continued to rebuild and upgrade their locomotives, their weights continued to change over the service life of each locomotive.

Changes in locomotive weight were usually recorded in the diagram sheets, with many sheets having a list of individual locomotives that have had a particular change or modification completed. Changes included addition of stokers, superheaters, and larger drivers and cylinders, and booster engines mounted either to the trailing trucks or under the tenders. Conversion from coal burner to oil burner, or from oil burner to coal burner also changed a locomotive's weight. Another feature was whether or not a series of locomotives was converted to be equipped for passenger service, which included train signals and steam heating connection.

Each of these new features changed a locomotive's weight, with each series, class, or single locomotive diagram sheet getting a revision to show the new weight. However, some diagram sheets do not show a particular change, but examination of photographs reveals that the modification was in-fact completed. Too many times, paper records did not get updated, meaning that "official" records are not always as reliable as researchers would like.

Another factor is that the term "weight" has been found to be either operating weight or weight on drivers, with both being labeled as "weight" or "engine weight." In this roster, especially for older, pre-1890 locomotives, if the source does not specify which weight is given (operating weight, engine weight, weight-on-drivers), then no weight is shown.

This roster of Union Pacific steam locomotives uses the best available weights for UP's locomotives, drawing from as many sources as may be available. But in many cases the weight is ignored. This is because in the source material, locomotive weights in a particular group vary considerably. Many lists in the source material show "weight", but the number given is almost useless without knowing for sure if the weight given is weight-on-drivers, engine weight only, engine weight loaded, or engine and tender weight.

Named Locomotives

(Read more about Union Pacific's named locomotives in the 1864-1867 period)

OSL 4753, a USRA 0-6-0

(First published to the UtahRails.net blog on December 19, 2010)

I recently received a question via email about OSL 4753, one of five USRA 0-6-0s operated by Oregon Short Line. I thought I’d share the results of my research.

OSL 4753 was an 0-6-0 built to the USRA pattern. While lettered as “Union Pacific”, number 4753 was owned by Oregon Short Line. It was one of a group of five similar locomotives built for Oregon Short Line Railroad in January 1919 to fulfill a need for additional switching locomotives. They were numbered as OSL 4753-4757. Union Pacific Railroad, OSL’s parent company, had received ten identical locomotives a month before, in December 1918. These ten locomotives were numbered as UP 4451-4460, but were renumbered to UP 4600-4609 in September 1920.

The USRA was the United States Railway Administration, which took over the operation of America’s railroads on March 21, 1918 to improve the efficiency of America’s railroads during World War I. It continued to operate and “administer” the railroads until March 1, 1920. One review has stated that over 100,000 freight cars and over 1,900 steam locomotives were built for the USRA, at a cost to the government of $380 million.

Prior to the USRA takeover, and beginning in 1905, Union Pacific had been purchasing 0-6-0 switching locomotives built to its own design, usually referred to as Common Standard, or CS. Starting with number 4350 in 1905, Baldwin Locomotive Works had continued to deliver CS design 0-6-0s on a regular basis, usually in groups of five, ten, fifteen, or twenty locomotives. The most recent group was UP 4431-4450, which were delivered in March through May 1918. Union Pacific and its subsidiary railroads, including Oregon Short Line Railroad, continued to need additional locomotives, and the increased traffic due to the war only made the need worse.

USRA controlled the manufacture and delivery of locomotives for all of the railroads under its “administration,” and set the priority of locomotive manufacture on a nationwide basis. Union Pacific requested additional 0-6-0 switching locomotives, and USRA assigned the order to the American Locomotive Company. ALCo’s Pittsburgh Works delivered UP 4451-4460 (10 locomotives, later UP 4600-4609) and OSL 4753-4757 (5 locomotives) in late December 1918 and early January 1919 as part of a single order of a total of 70 identical locomotives that were distributed among several of the nation’s railroads. They were all initially lettered as “U.S.” and retained this lettering until USRA returned the railroads to their own control in March 1920. Included in the financial settlement between USRA and the nation’s railroads upon return of control, was that the ownership of all equipment purchased by USRA and assigned to particular railroads, would pass to the assigned railroads. This settlement included the fifteen USRA-pattern 0-6-0s for UP and OSL.

Union Pacific assigned its USRA 0-6-0 switchers to its yards in the Omaha and Council Bluffs area, but later moved them as a group to its switching yards in Kansas City. The locomotive assignments for 1949 and 1950 show that UP’s engines were assigned to Marysville, Ellis, Salina, and Kansas City, all on the Kansas Division. They were removed from service and retired between 1947 and 1956.

Although research has not yet found documents that say where OSL assigned its five USRA 0-6-0s, a guess would be that they were assigned to the railroad's large switching yards in Pocatello and Nampa, Idaho. Diesel switchers were first delivered beginning in 1940. Several diesel switchers were assigned to each of the large switching yards on UP’s western divisions, including all of its three subsidiaries Oregon-Washington Railroad and Navigation Company (OWRR&N), Los Angeles and Salt Lake Railroad (LA&SL), and Oregon Short Line Railroad (OSL), with each division’s steam switchers being moved east to UP’s Nebraska and Kansas divisions to consolidate maintenance.

The locomotive assignments for 1949 and 1950 show that the remaining OSL engine, numbered as OSL 4753, was assigned to "protect" Boise, Idaho, meaning that it was being held in standby status in case the assigned diesel switcher could not perform its duties. But there were several diesel switchers assigned to the nearby Nampa yard, so the likelihood of OSL 4753 returning to service would have been slim. It was retired in March 1955.

(A photo of UP 4454, one of UP's USRA 0-6-0 switchers)

(Read the Wikipedia article about the USRA)

Power Reverse Gear

On January 5, 1933, the federal Interstate Commerce Commission issued an order that defined the use of power reverse gear on steam locomotives. Previous to the 1933 order, it was optional for the railroads to equip a steam locomotive with either hand operated or power operated reverse gear. At the date of the order there were in use in the United States about 31,597 steam locomotives equipped with hand reverse gear and 28,925 equipped with power reverse gear.

A steam locomotive's reversing gear, or 'reverse gear' as it was usually called, was the mechanism which controlled the position and movement of the locomotive valve gear and valves which admit steam in the cylinders, and was the method used to control the direction of movement of the locomotive. Two general classes of reverse gears were in use. First were manually operated reverse gears which depended upon the use of muscular force of the engineer and the force exerted by the counter-balancing weights and springs, for their operation. The second class were power reverse gears which with an auxiliary mechanism brought the force of compressed air into play, so that less muscular effort was normally required by the engineer to reverse the locomotive. The engineer operated either class of reversing gear by means of either a lever or hand wheel (used with screw type of gear) located near his seat-box in the locomotive cab.

With its ruling in 1933, the ICC determined that a reversing gear was a safety device, and therefore subject to the Boiler Inspection Act. The ruling was the result of a complaint by the Brotherhood of Locomotive Engineers and the Brotherhood of Locomotive Firemen and Enginemen, and alleged that, while power reverse gear is a suitable, safe, and practical device, manually operated reverse gear is inherently unsafe and unsuitable in principle and design, that it subjected employees and the traveling public to unnecessary peril, and that the use of locomotives equipped with hand reverse gears violated the Boiler Inspection Act.

The rule of the Boiler Inspection Act, known as Rule 157, defined reversing gear as follows: "Reversing gear, reverse levers, and quadrants shall be maintained in a safe and suitable condition for service. Reverse lever latch shall be so arranged that it can be easily disengaged, and provided with a spring which will keep it firmly seated in quadrant. Proper counter balance shall be provided for the valve gear."

The railroads sued the ICC, saying that the commission did not have the authority to make the rule under the federal Boiler Inspection Act. The case went to federal District Court, which set the ICC order aside. The ICC appealed the decision to the U. S. Supreme Court, and two years after the original rule, the court agreed that the ICC did in fact have such authority.

On January 7, 1935, the U.S. Supreme Court affirmed the order of the lower court. The lower court's decision amended the rule of the Boiler Inspection Act to require the railroads to equip all steam locomotives built on or after April 1, 1933 "with a suitable type of power operated reverse gear." Similarly, the railroads were to equip, "the first time they are given repairs defined by the United States Railroad Administration as Class 3, or heavier," all steam locomotives then in road service "which weigh on driving wheels 150,000 pounds or more," and all then used in switching service "which weigh on driving wheels 130,000 pounds or more." The order required that all such steam locomotives be so equipped before January 1, 1937. The order also mandated that air operated reverse gear (including power gear already installed) would have a suitable steam connection, so that in case of air failure steam could be quickly used to operate the reverse gear.

(Link to U. S. Supreme Court case 293 U.S. 454, U. S. vs. B&O Railroad; Decided January 7, 1935)

This subject came up because a recently uncovered photograph of UP Shay no. 61 showing an unusual mechanical device on the fireman side of the locomotive. The result of the discussion was that this was a power reverse gear mounted on the fireman's side running board ahead of the cab. It was operated by the engineer by levers and rods across the backhead, through the fireman's cab wall, to the reverse gear. The reverse gear then actuated the cylinders on the opposite side of the locomotive by a combination of levers and rods that were installed under the cab floor. Yet to be answered is why UP no. 61 had the device, at 200,1000 pounds weight on drivers, but UP Shay no. 59 did not, with its 181,800 pounds weight on drivers. There are photos of both sides of no. 59 on its way to be scrapped, and there is no similar mechanism visible. A simple explanation might be that no. 59 never received Class 3 repairs after the power reverse rule was mandated.

Radios of UP Steam Locomotives

The following comes from Kratville and Ranks' "Motive Power of the Union Pacific", page 14.

Radio communication equipment was installed after World War II to many freight locomotives including some 800, 3800, 3900, and 9000 types. Most were equipped with this innovation in 1948 and 1949, principally for Kansas Division work, the aerial being located on the cab roof.

The authors of that book published in 1959 had access to incredibly detailed information directly from internal files at the mechanical department. Since the book was first published in 1959 it is possible that there was a detailed list at the time, but a detailed list has not survived.

Kratville and Bush's "The Union Pacific Type, Volume II," published in 1995, adds the following on page 59, but only for the 9000-class engines.

Radios were authorized for use on the Kansas Division in June 1947, to be added to four 4-12-2s and four cabooses (2651, 2682, 3200, and 3251) to enhance operations. Installations were made on the 9031, 9052, and 9057 in April 1948, at Kansas City, followed by the 9046 in May. In August, the 9043 was also given radio equipment. All locomotives were assigned Kansas City-Marysville work. The original sets were all three-channel Farnsworth radios. In 1949 Motorola sets replaced the Farnsworth type on two locomotives. Application included special turbot-generator equipment, placed ahead of the whistle on the boilers. Equipment placement was divided between the locomotive and tender. The Farnsworth equipment was mounted near the cab roof above the gangway. The Motorola equipment was placed in a box on the right side of the tender. See the Tenders section of this chapter for a description of the box. The antenna was first on the tender but moved to the cab roof in early 1949 for easier maintenance, being first tested on the 9043 and 9057. When new, the sets amounted to about $3000 each.

The radios were removed from the 9043, 9046, 9052 and 9057 in October 1953, the 9031 having been removed earlier.

Rebuilt Locomotives

From the earliest days, the railroads and locomotive manufacturers were constantly working to improve a locomotive's ability to produce and use higher steam pressures and steam temperatures. As the quality of steel improved, steam locomotive boilers increased in size along with their ability to hold higher steam pressures. Better steel also allowed better and stronger mechanical parts, with better tolerances between moving parts. Drive wheel diameters increased, as did cylinder size. Boilers continued to become larger as better materials were developed. Locomotives continued to become larger and larger as their boilers and cylinders and drive wheels continued to grow.

To take advantage of better materials and improving designs, Union Pacific and most larger railroads began their own rebuilding programs to improve the performance of their older locomotives. This usually included increasing drive wheels and cylinder sizes. In the 1880s, as better quality and stronger steel became available, new boilers were also included in the rebuilt locomotives, as well as new frames and new axles. By the 1890s, a rebuilt locomotive usually included new drive wheels, new cylinders, new boiler, and new almost everything else. Essentially a new locomotive. But for bookkeeping reasons, it was a rebuilt locomotive.

This brings into the discussion, What is a locomotive? Is a locomotive its frame and drive wheels? Is a locomotive its boiler? At what point in the process does a rebuilt locomotive actually become a new locomotive. How many of its components need to be changed before it is no longer a rebuilt locomotive?

In almost every instance, unless a locomotive was received new from one of the builders, any change to its configuration was considered to be a rebuild, even if as one observer put it, "The bell was lifted up and the entire boiler, cab, frame, cylinders, and drive wheels completely changed, and the bell was re-installed."

The worst cases resulted in a new class being created for the rebuilt locomotives that drew on a pool of older locomotives, without the number-to-number sequence being followed in the before and after locomotive numbering scheme. The 55 Union Pacific 800 series engines of the 1880s and 1890s, along with the four OSL 100s and the 26 OSL 500s of the late 1890s are the most obvious and most problematic examples.

One example was UP no. 815. It was rebuilt at Evanston, and is the only locomotive of the 800- and 900-series known to be rebuilt at that location. An older engine, in this case no. 166, was taken into the shop and disassembled. New castings and other heavy items to be upgraded were shipped from Omaha, and the "rebuilt" locomotive was reassembled. (James Ehernberger, email dated February 5, 2005)

(Roster listing of the 55 Union Pacific 800 series engines; rebuilt in the 1880s and 1890s, all were 4-4-0 type)

(Roster listing of the four OSL 100 series engines; rebuilt in 1897, all were 4-4-0 type)

(Roster listing of the 26 OSL 500 series engines; rebuilt in the late 1890s, all were 4-4-0 type)

Signal Lights

The following comes from Dick Harley:

The initial drawings for a Mars light on an FEF steam locomotive on a test basis were issued December 1945. The "test" note was removed and other drawings issued in January 1947. This may have been related to a proposed Rules change.

The July 1, 1946 Rule Book does not mention a Rule change concerning warning or signal lights.

The July 1, 1954 Rule Book does have such a rule, 17 (E), but that was at least six years after the locomotives had been modified.

The rule in the July 1954 Rule Book reads:

17 (E). Oscillating red headlight on engines so equipped must be displayed under the following conditions:

When train becomes disabled or makes sudden stop due to unusual occurrence, or when an adjacent track is obstructed or there is possibility of it being obstructed;

When head end protection is required;

When occupying main track in meeting an opposing train, until opposing train dims its headlight and switch is lined to permit opposing train to enter siding, except this does not apply in CTC territory.

When red headlight is displayed, an opposing train on same or adjacent track must stop before passing headlight, ascertain the cause and be governed by conditions.

Skyline "Smoke Duct" on UP 815

In 1940, Union Pacific experimented with a skyline casing on UP 815, an FEF-1 class "little" 4-8-4.

William Kratville wrote in his book "The Mighty 800," on page 80:

The biggest single series of tests were performed on the smokebox and related items. It was not long after the second group entered service that drifting smoke was noticed so the 815, in line for the shop, was equipped with a giant sheet metal casing on the boiler top. Similar in appearance to the Southern Pacific's famous "skyline casing," the hood was supposed to lift smoke upward and also be a sincere effort at stream-styling. The unit had been designed hurriedly and according to directions of other than strict design men. From first glance the test and design teams deemed the hood ineffective but thousands of miles of tests were performed with the 815 —all proving what the men who first climbed aboard for tests had thought—the unit didn't do the job! The circulatory plan was to form air currents which lifted the smoke but even at high speeds the currents were not properly directed or of enough velocity to overcome the smoke. And at slower speeds the unit was completely useless, the smoke drifting down along the boiler into the cab. The hood was officially designated a "monitor" hood and was assembled in sections—domes, turret and cab, etc., in early spring, 1940.

Within two years all the 835s and 820s were equipped with wings. In 1950, the first group began receiving wings as they were put more into freight service. Finally, all the 4-8-4s were wing equipped. The 840 was the test engine for the smoke wing development, the 838 first to have them applied as part of a program.

"The Mighty 800," on page 81, has a photo of UP 815, but is more of an front-end angled shot. The caption calls the skyline a "smoke duct."

(See also: "Wind Wings" on 800 class, below)

Smoke Deflectors

Smoke Deflectors -- Information about the use of smoke deflectors on Union Pacific steam locomotives. Includes a link to photographs and drawings.

Smoke Lifters

Smoke Lifters -- Information about the use of smoke lifters ("Wind Wings") on Union Pacific steam locomotives. Includes a link to photographs and drawings.

Smoke Stacks

Large Exhaust Stacks on UP -- Information about the large exhaust stacks unique to many of Union Pacific's steam locomotives; a design that accompanied the use of annular port "Sweeney" nozzles, and the later Multiple Jet nozzles, inside the smoke boxes.

Snow Plows

The following 2-8-2 Mikado (MacArthur) steam locomotives on Union Pacific and its subsidiaries were equipped with snow plows mounted to their pilots:

Small Plow

Large Flat Plow

Large Curved Plow

(Source: Union Pacific Prototype Locomotive Photos, Volumes 28 to 33, published by Union Pacific Historical Society)


One feature all published listings of steam locomotives have in common, whether from the railroads themselves or from other sources, is a locomotive's drive wheel diameter and cylinder diameter and stroke, along with the Whyte system wheel arrangement. From that point, the information that is included seems to vary somewhat. Union Pacific and its subsidiary companies each produced locomotive diagram books (also known as folio books) that included basic dimensions and weights. The diagram sheets usually included boiler characteristics such as firebox dimensions, grate area, and flue sizes and quantities. This boiler information, along with the pressure the boiler carried, was a direct indicator of a locomotive's capacity to do work on a sustained basis.

Locomotives are machines designed to do work, and like all machines, knowing a locomotive's horsepower (literally the number of horses needed to do the same amount of work) is an indicator of a locomotive's ability to pull a train, and to continue pulling a train over a required distance. In the case of steam locomotives, converting steam pressure from the boiler, to mechanical work for the drive wheels included pressurizing a set of cylinders that contained pistons, which in turn forced the drive wheels to rotate. There were several variables such as weight, resistance to rolling, and overall efficiency of the every piece and part. Additional variables for steam locomotives included the heat and pressure of the steam itself, the feature that for many is what brings a steam locomotive to life.

The formula to calculate a locomotive's horsepower includes knowing its drive wheel diameter, the inside diameter of its cylinders (known as bore), the distance that the pistons moved within the cylinders (known as stroke), and the pressure of the steam in the boiler (known as boiler pressure, or b.p.). These three numbers will give you a locomotive's tractive force in pounds (note that overall locomotive weight is not a factor). A locomotive's horsepower comes from knowing its tractive force and the speed being traveled. (Read more about horsepower for a steam locomotive)

Because the sources vary greatly as to the information presented, and the source and accuracy of the information itself, this roster presents only drive wheel diameter and cylinder size, with variations noted as necessary. If the source is Union Pacific's own diagram books, then the various weights are also included, along with the fuel burned. The diagram books themselves vary over time due to revisions and being redrawn. These differences are noted as necessary.

I have decided to mostly ignore specifications unless they are documented as being as-built, as-delivered from the builder, or are taken from a dated folio diagram sheet. I'm sure Union Pacific was like all other railroads, and for UP, rebuilding and upgrading cylinder size and driver size was an almost constant effort. It is really the only way they had to increase a locomotive's performance.

Superheaters and Piston Valves

When did UP and the subsidiary roads start using superheated boilers? Was it before or after the 1915 renumbering?

The 1911-1918 diagram book shows only UP 2-8-0s 403, 409 and 410 as being superheated in the 402-419 series, but the 1919-1937 book shows none of the 2-8-0s in the 402-419 series as being superheated and only 407, 411 and 413 remaining, and they were saturated.

Limited (in print) evidence thus far suggests the first superheaters arrived in 1912 with the 4-6-2 Pacifics and 2-8-2 Mikados delivered that year. The major difference between the MK-1 class, and the superheated MK-2 class was 800 pounds, the weight of superheater equipment. This same 800 pounds is also the difference between superheated 400 class 2-8-0s, and non-superheated (known as saturated) locomotives of the same class.

The earliest evidence (in print) suggests that retrofitted superheaters began in 1914 and were very spotty for quite some time. Clearly the slide valve locos were not great candidates, they needed the wet steam, but that is an area I have not spent very much time studying.

Both the Schmidt superheater (used on the UP 400 series of 2-8-0 locomotives) and the piston valve was invented and patented in the 1890s by Wilhelm Schmidt, a German mechanical engineer who worked for Prussian State Railways.

Research suggests that the earliest use of piston valves in the U. S. was by Baldwin on their Vauclain compound locomotives to allow inboard valves that solved the outside clearance problems (they had to stay within 9 feet 3 inches overall width). The Vauclain design was at times known as "four-cylinder compound" as compared to the Worsdell two-cylinder cross compound design as used by Schenectady on UP 1320 and 1321.

Wes Camp wrote the following summary of saturated steam vs. superheated steam (Trainorders.com, September 26, 2020):

'Saturated' refers to the heat constant of the steam. When water is heated to boiling, especially in a closed container, like a boiler, the steam that collects on top of the water (in the space) is at the same temperature as the as the liquid water.

Steam is the gaseous state of water. The other two are: solid (ice), and liquid.

In thermodynamics terms, steam is said to be 'saturated' when it is in contact with the boiling water.

The principle distinction is that it takes eight-times the heat content (British Thermal Units, or BTUs) to convert the boiling water to steam, as it took to raise the water to the boiling temperature. So, if it takes 10,000 BTUs to get a quantity of water up to boiling, it takes an additional 80,000 BTUs to get it to be steam ... although it is heat-saturated at that temperature ... a hotter fire will not raise the boiling point, it will simply try to boil faster. On a stove, pot of boiling water will not get hotter, but you can boil it 'off' at a faster rate, and in a shorter time.

In thermodynamics, the term 'saturated' does NOT refer to the moisture content of the dry steam, it only refers to the fact that the steam is at the same temperature as the boiling water in the vessel.

Steam flows towards the lower pressure --- when the throttle is opened, the steam flows towards the cylinders --- towards the lower pressure volume. On the way, as the pressure drops, some of the steam cools and condenses back to water. That is unavoidable, and a consequence of saturated steam.

Same thing happens in the cylinders: more expansion, more water precipitates out. Locomotive compounding was an attempt to get more work out of the remaining residual steam pressure.

There were variations of compound locos, some by design, some by devising ways around existing patents ... and patent laws.

Even back in the hey-day of compounding, it was recognized that when starting, there was no exhausted steam to be conveyed to the larger cylinders. 'Starting' or change-over valves were introduced from the beginning. These two-position valves used spring-loaded regulators to limit the 'live steam' pressure fed to the much larger pistons.

Steam at full boiler pressure can over-power the low-pressure pistons and cause severe spinning of the drivers. Thus, reduced pressure, 'live steam' was used to get the trains up to track speed, when starting. When up to speed, engineer would manually close the change-over valve to change the steam paths to 'serial' steam use.

Starting in 'simple' was thus a 'parallel' use of steam, compounding was a 'serial' steam path.

The change-over valves were always a manually operated device, operated by the engineers. At slow speeds, you could shift back to simple to get over the hard pull. The fireman had to be ready, though, with a good hot fire. The more you re-use the steam, the colder, and wetter, it gets.

'Superheating' occurs when the saturated steam is routed through pipes surrounded by very hot flame tips ... the steam molecules are vibrating at a very fast rate, and collisions occur. When routed through the superheater units, the steam increases in temperature, along the flow path. The molecules vibrate with greater amplitude and great separation. This separation means a much reduced amount of water is used to get the same amount of 'work'.

Superheated locos, when hot enough, never drop the steam temperature back the saturated temperatures. It revolutionized the whole concept of steam locos --- from 'pressure operated machines' to 'heat engines.'

After the perfection of the Schmidt Superheater in Germany about 1900, it immediately doomed the construction of the old, saturated, and compound locos.

In later years, compound articulated, using superheated steam were used very successfully. The high-pressure steam cylinders pumped, still superheated steam, towards a second use in low-pressure cylinders. However, the steam was still hot enough to be in the superheated state, often exhausting, at greatly reduced pressures, superheated steam up the stack to the atmosphere.

The second use of the steam meant that the high-pressure pistons were subject to back pressure from the pipe supplying the low-pressure pistons --- in effect, the high-pressure cylinders aided the low-pressure cylinders by "pumping them along."

"Compounding" is still around today: steam turbines with multiple stages, have successive states made in larger and larger diameters towards the exhaust end. That way each stage delivers the same torque to the shaft, but from lower pressure steam, than at the admission jets. Jet engines have their impellers at successively larger diameters, further down the shaft -- to compensate for the reduced pressure gradient.

Tractive Force and Horsepower

From The Streamliner, Volume 2, Number 4, page 28

Formula for converting tractive force to horsepower at the rails (both steam and diesel locomotives).

(tractive force in pounds) x (speed in miles per hour) / 375 = (horsepower at the rails)

(drawbar pull in pounds) x (speed in miles per hour) / 375 = (drawbar horsepower)

(tractive force in pounds) x (speed in feet per minute) / 33000 = (horsepower)

For steam locomotives:

(0.85 boiler pressure in pounds) x (cylinder diameter in inches, squared) x (stroke in inches) / (driver diameter in inches) = (tractive force in pounds)

Train Indicators

(September 18, 2017; Dick Harley email)

Number Boards vs. Indicators -- In the steam era, those number displaying devices were called "train number indicators", "train indicators", or simply "indicators" - NOT "number boards". In the early 20th century, their use was governed by part of Rule 19. But after 1940, those rules became Rule 24 - Indicators.

From the 1919 rule book:

19 (C). A train equipped with train indicators must not leave its initial station without the indication properly displayed. When the identity of a train is changed, the indicators must be changed to correspond. Before making such change, the safety of other trains must be fully considered.

2 for Train No. 2.
1-2 for First 2.
X-162 for Extra 162.

From the 1946 rule book:


24. A train with engine equipped for display of indicators, must not leave its initial station without the train number being properly displayed in the indicators.

Helper engine will also display indicators when it is the lead engine or coupled to the lead engine, but train number must not be displayed until engine has been coupled onto train.

When number of train is changed, indicators must be changed to correspond. Before making such change, movement of other trains must be safeguarded.

When an engine is cut out of a train, train number must be removed promptly from indicators.

2 for Train No. 2.
1-2 for First 2.
X-162 for Extra 162.

Research suggests that the term "number board" did not come into common use until the diesel era. In mid-1965, rules were changed so that train numbers were no longer displayed in indicators. At that time, only the engine number was displayed and that did not need to be changed. So a single 'board' displayed the whole engine number and was not easily changeable. All road diesels built before 1965 had 5-digit individually changeable indicators.

(Read more about number boards on diesel locomotives)

Triple Stack 800s

The three-stack arrangement for FEFs was proposed in cost estimates dated May 17, 1946. UP drawing 744-CA-33003 "Smoke Stack Arrangement, (Three Smoke Stacks)" was issued 8-30-46. It was to be used on FEF-2 and FEF-3 locos as a "Test Application". The stack base casting shown on that drawing is the same as for the stock FEF-3 double stack, though it is modified for the three stacks. The stacks themselves are 16" diameter choke and 19" inside diameter (ID) at the top, whereas the stock FEF-3 double stacks were 21-1/2" diameter choke and 26-1/2" top ID. The most common term in the literature for this arrangement seems to be "triple stack".

No shop records have yet been found to date the actual installation of these triple stacks. Photographic evidence shows that triple stacks were applied to FEF-3s 835, 837, and 839, and later to FEF-2 831. The statement in Kratville's The Mighty 800 book that 832 also was triple stacked appears to be in error. Recent photo research indicates that the triple stacks were installed after the FEFs had been converted to oil fuel in 1946. While 835, 837 and 831 appear to only have sheet metal plates on the side of the stacks, 839 received a full casing (like the stock double stack FEF-3s) around its three stacks, making it slightly harder to identify. A good identifier is the air pump exhaust steam pipe entering the side of the stacks between the second and third stack. It appears that all four of these engines kept their triple stacks until retirement.

Photos of the three FEF-3 locos with triple stacks can be found in the UPHS publication Union Pacific Prototype Locomotive Photos, volume 5.

(see also: The Streamliner, Volume 21, Number 3, Summer 2007, Q&A 404, page 5)

UP 0-6-0 4439 Retired Due To Pollution

(March 19, 2017)

(View the roster listing for UP 4431-4450, including UP 4439)

In February 1957 Union Pacific 0-6-0 4439 was the subject of a violation of the regulations of the Air Pollution Control District of Los Angeles County. One of the District's inspectors, with the title of Air Pollution Control Officer, had observed that during the occasional run to blow out the accumulation of soot from 4439's firebox and flues, the smoke exhaust had exceeded the allowed 5 minutes of smoke matching No. 3 on the Ringelmann scale. The Ringelmann scale was a measure of visible smoke, with clear being 1, and the darkest black being 5. The violation was observed as being No. 5 for a period of 4 minutes 5 seconds.

During a hearing before the Air Pollution Control Board on February 7, 1957, the master mechanic of the Harbor Belt Line Railroad, operator of 4439, stated that the oil-burning locomotive was being forced to burn domestic-grade oil which resulted in excessive build up of soot. On a daily basis, the locomotive was run a distance of 440 yards at full throttle with brakes applied, to blow out the soot by the use of sand drawn through the firebox and flues. This was daily except on Mondays. Mondays were the busiest day for the railroad and 4439 was needed as additional motive power to assist the railroad's two diesel locomotives (Two locomotives on a rotating basis from the Harbor Belt's owning railroads: UP, SP, and AT&SF) No. 4439 was held in standby until Monday nights when it was used on the 4 to 8 shift, or the 4 to 12 midnight shift, to aid in the expedited movement of rail cars upon the arrival of the banana boat with its perishable cargo. On the other days of the week, 4439 was used solely as a stationary steam boiler, which resulted in an accumulation of soot.

The railroad had asked for a variance, which was discussed at a Board hearing on February 7, 1957. Evidence was given, including the above facts and summary of operation. A Union Pacific representative testified that the 4439's flues would be out of date on November 1, 1957, and in violation of federal ICC boiler safety laws. At that time Union Pacific planned on retiring 4439.

On February 15, 1957, the Pollution Board notified the railroad of its decision, which was to allow the continued operation of 4439, allowing a six-month variance of a maximum of 6 minutes of 5 on the Ringelmann scale, the maximum. The railroad was also allowed to continue using domestic heating oil as its fuel, but only for the same six-month time period.

March 27, 1957
The following comes from the March 27, 1957 of the Wilmington Daily Press Journal newspaper:

Old 4439 Soon Won't Give A Toot.

The only steam whistle in Los Angeles County is living on borrowed time. Borrowed, that is, from the Air Pollution Control District. Currently the noise maker is mounted on Harbor Belt Line engine 4439 — which is slated to die via the 'cutting torch on November 1.

Seems the smog boys took a dim view of 4439 and the steam whistle recently because of a Ringelmann Chart reading of three. The Baldwin 0-6-0 type switcher or yard engine is the last of the working steam locomotives here in Wilmington. All others have been replaced with Dieselized work horses.

Old 4439, built in 1918, is needed by Union Pacific railroaders one day a week for duty at the banana docks. The hours of labor are from 4 p.m. until 8 p.m. and sometimes until midnight. Of course the steam whistle must be brought into play during this time.

The smog board has considered the facts and is allowing the engine to continue until the November date. However, the variance permits only an opacity not to exceed a number five reading on the Ringelmann Chart for no more than six minutes in any one hour.

August 26, 1957
The following comes from the August 26, 1957 issue of the Los Angeles Times newspaper:

UP Donates Locomotive to Travel Town.

Switch engine 4439, the last steam locomotive operated in the Los Angeles area, has been donated by the Company to Griffith Park's Travel Town, where it will arrive next Friday, it was announced yesterday by the City Recreation and Park Department.

No. 4439, built by the Baldwin Locomotive Works in 1918, was assigned to the Harbor Belt Line in 1946, after it had been removed from yard service by the Southern Pacific, Atkins said.

Retired permanently in June, 1957, the locomotive has been in the Union Pacific's shops, 4341 E Washington Blvd., getting a new coat of paint and a complete refurbishing.

According to Union Pacific records, no. 4439 was retired in August 1957 (at the end of the six-month variance period). The TravelTown web site says that 4439 was donated immediately after retirement to the City of Los Angeles and by late November 1957 was on display at TravelTown.

(Read more about UP 4439 at TravelTown)

A bit of history for pollution control in Los Angeles...

1946 -- The Los Angeles County Air Pollution Control Board was established to study the causes of visible air pollution in the Los Angeles basin.

1953 -- The Los Angeles County Air Pollution Control District was established as the government entity with authority to control air pollution in Los Angeles County. The LACAPD was later combined in 1976 with other air pollution control districts to form the South Coast Air Quality Management District, the air pollution control agency for all of Orange County and the urban portions of Los Angeles, Riverside and San Bernardino counties.

UP 2-8-0 440

(July 3, 2017)

Union Pacific 2-8-0 no. 440 is displayed, since October 2005, at Antigo, Wisconsin, as C&NW 440.

The following comes from the Mid-Content Railway Museum web site:

UP #440 began life as a Vauclain compound built by Burnham, Williams and Co. (Baldwin) in December 1900 as Union Pacific #1660. Compound locomotives used steam twice. Steam was first admitted into a set of smaller high-pressure cylinders. It was then exhausted into a set of larger low-pressure cylinders. The benefit of increased fuel efficiency was offset by the increased maintenance and expense of the complex machinery. Another disadvantage was the development of uneven stress and torque on the crosshead (where the piston rod was connected to the side rods that drove the wheels). Other more practical methods of increasing a locomotive’s efficiency were soon developed (superheaters units that “superheated” the steam before it was used in the cylinders, for example). All these factors resulted in #1660’s class being “simplified” (converted to standard single-pressure cylinders).

#1660 was renumbered #440 in 1915 after her shopping to a simple locomotive. In later years, #440 was used in branchline service on the UP’s various lines in Kansas and Nebraska. Forty years later in 1955, #440 was retired and donated to the Nebraska State Fair Association and placed on display at the fairgrounds in Lincoln, Nebraska. When the fairgrounds were converted into a university coliseum, #440 was saved by the Cornhusker Chapter of the National Railway Historical Society. Unable to find a home for the venerable 2-8-0 in the Lincoln area, the chapter offered #440 as a donation to Mid-Continent. She was moved on her own wheels from Nebraska via Sioux City, Iowa and Mankato, Minnesota and arrived at North Freedom in June of 1975.

#440’s boiler was evaluated and determined to be restorable. Not long before #440 was retired by the UP, she had received new firebox side sheets. Other components of the boiler appeared in good condition. In the mid-1980s, funding was raised to begin replacing some 800 flexible staybolts, sleeves, and caps. Most had severely corroded during #440’s fairground display years. New techniques had to be devised to remove the remains of the existing caps and sleeves, and manufacture new ones from materials that meet today’s more stringent FRA and ASME boiler codes. By 1989, work was suspended due to lack of funding. #440 was stored, awaiting the day she could return to the shop for further work.

UP #440 was traded by Mid-Continent in 2004 to Trans-Northern in return for Copper Range #29, a locomotive that better fit the Upper Midwest focus of Mid-Continent and matched two restored Copper Range passenger cars already in the collection to form a complete train.

Plans by Trans-Northern to restore #440 to operation and lease it to a third party failed to happen. The locomotive was instead sold to the Langlade County Historical Society for display in Antigo, WI. The locomotive arrived there on Oct. 31, 2005. Cosmetic repairs were completed, including construction of a new cab. Although #440 was never owned by the Chicago & North Western, during its restoration, the locomotive had C&NW livery added in honor of Antigo’s close association with that railroad.

(Trans Northern, Inc., is, or was, the parent company of shortline railroads in Wisconsin (Algoma Railroad; Chippewa River Railroad Company; Brillion and Forest Junction Railroad), operating over former Milwaukee Road tracks in the Chippewa Valley. Trans Northern, and its affiliate Mineral Range, Inc., serve as the official organizations for Clint Jones and his interest in railroad preservation and operation.)

The following comes from the Langlade County Historical Society's web site:

The 440 locomotive is a 2-8-0 Baldwin constructed in 1900 as UP 1660 and is a close relative of the Chicago and Northwestern 175, the last steam engine to travel through Antigo in 1957. The Society tried, but was unsuccessful in purchasing that locomotive.

No. 1660 was renumbered 440 in 1915 after modification. She was used on the Union Pacific's various lines in Kansas and Nebraska. In 1955 the 440 was retired and donated to the Nebraska State Fair Association and displayed in Lincoln, Nebraska. When the fairgrounds were converted into a university coliseum, the 440 was saved by the Cornhusker Chapter of the National Railway Historical Society and donated to Mid-Continent Railway Museum in North Freedom, Wisconsin. She was moved on her own wheels and arrived at North Freedom in June of 1975.

At Mid-Continent the locomotive was evaluated with an eye on restoration; to a working engine. In the mid-1980s, funding was raised to begin restoration, but by 1989, work was suspended due to lack of funding.

The Langlade County Historical Society then mounted a successful $75,000 fundraising campaign to purchase and restore the engine as a static, non-working display. She arrived in Antigo on Oct. 31, 2005, with her tender a few weeks later.

Over the course of the next 18 months, she was lovingly repaired and restored by a largely volunteer cadre. A new 440 cab was constructed to replace the original, which was too badly damaged for restoration, and by late May, 2006, she once again resembled what she once must have been.

The spring of 2007 saw the construction of a roof for the locomotive and the museum’s caboose as well as final touches to the locomotive.

(Read more about UP 440, as part of the original UP 420-459 group)

Union Pacific Shops

(to be compiled from various issues of UP's Form 70 accounting books)

Union Pacific Shop Locomotives

UP Shop Locomotives -- A separate roster listing of Union Pacific shop locomotives assigned to shops in Omaha and Cheyenne.

Vanderbilt Tenders

The following comes from SteamLocomotive.com:

A round tank has several advantages over a rectangular tank.

  • A round tank holds more than a rectangular tank of the same surface area.
  • A round tank (a cylinder) is stronger than a rectangular tank (a box).
  • A round tank is lighter than a rectangular tank of the same capacity (partially because a rectangular tank requires a great deal of internal bracing).

On May 31, 1901, a patent was issued to Cornelius Vanderbilt for a tender with a cylindrical water tank (Cornelius was the great grandson of the Commodore). Some railroads went for Vanderbilt tenders in a big way. Others did not. Railroads that adopted the Vanderbilt style tender for many of their steam locomotives. Among them was Union Pacific.

There were five separate patents issued to Cornelius Vanderbilt for his tender body design. They were:

The Vanderbilt Patent plates applied to UP locomotives, including OSL, OR&N and LA&SL locomotives, showed four successive patent dates of July 9, 1901; July 16, 1901; September 3, 1901; and October 4, 1904.

Oregon Short Line was the first among the Union Pacific Lines to receive a Vanderbilt tender-equipped locomotive, when in April 1902, OSL 4-6-0 no. 409 was delivered. It was a Vauclain Compound and was later renumbered to OSL 1571. It was equipped with a 7,000 gallon "Cylindrical" tender, UP Class 7-C.

Union Pacific received its first Vanderbilt in late 1903 from Baldwin with the delivery of the eleven 4-4-2 Atlantics, numbered as UP 1-10.

William Kratville wrote in Motive Power of the Union Pacific, "The 'Vanderbilt' type was first used on the system in 1903 and was so well liked that many variations of this were eventually built and the type was considered the 'standard' tender of the system until the Centipede type which actually resembles an overgrown Cylindrical model."

Patents expire after 20 years, meaning that the earliest Vanderbilt patents began expiring in 1921. UP's "Sport Model" 4-8-2 7000-class began delivery from Alco in 1922 and were equipped with 12,000 gallon tenders mounted on six-wheel trucks. As the original patents from 1904 expired in 1924, UP began receiving locomotives with massive 15,000 gallon, and later 18,000 gallon cylindrical tenders that were an improved version of the Vanderbilt designs.

Vanderbilt Tender on OR&N 197

Following is a summary of features of the 9-C (9,000 gallon, Cylindrical) tender attached to OR&N 4-6-2 197 being restored at the Oregon Rail Heritage Center in Portland, Oregon. (Gordon McCulloh, emails dated July 27, 2008):

The plate you describe (9C-307) is a Common Standard class 9,000 gallon cylindrical tender plate, serially numbered as 307. I have found no records to tell me where this tender had been assigned prior to being listed with the 3203 when donated in 1958.

Let me begin with some history of the tender numbering. The plate is not a builder's plate. Prior to patent expiration in 1922, all Vanderbilt tenders did carry a serially numbered Vanderbilt patent plate that was railroad specific. At this late date few remain and no records have been found in UP archives to define which numbers were on which tenders.

The first UP tender class to have Common Standard serial number plates applied did not come along until 1928, that with arrival of the third order for UP 9000s (4-12-2s). It is therefore the case that tenders built prior to that time were not identified with a unique plate under the Common Standards system, that not happening until many years after they had been built.

When standardized numbering began on older tenders in the 1930s it appears that it was solely for the purpose of tracking each tender's expenses, and therefore numberings were not representative of first or tenth or hundredth of that class that was delivered to the UP System. Tender numbers began at *01 in each class, unlike the locomotives that started with *00.

Records which I have constructed from a multitude of UP sources indicate that there were 327 9,000 gallon Vanderbilt tenders on the UP system. Besides those that were delivered with locomotives, there were just over fifty that were purchased as extras as tender upsizing and replacement were underway in many classes. The 9Cs were serially numbered 9C-101 thru 9C-400 and for some reason there were 19 more that were given plates such as X-19 or X-83 etc., being randomly applied and simply identifying them only as "extras" with no capacity markings.

Your P-2 Pacific locomotive (ORN 197/3203) was built with a 9R (9,000 rectangular), being the last in the first group ordered with that tank. The first 9Cs were built for UP System P-6 class locomotives in 1908, with the last group being built in 1920 for the P-13s. By 1910, passenger tenders normally had vestibule diaphragm adapters.

Photos of OWRR&N 3203 dating back to an Otto Perry shot taken at La Grande in July 1938 and two by Don Roberts, dated October 1946 and May 1949. All show it with a 9C tender.

Records which I have researched do not indicate that 9Cs were used with Atlantic class engines, but, over time one learns to never say never! The first A-2 Atlantics of 1903 came with 7C (7,000 gallon) tanks. These tanks suffered many failures and were soon replaced by whatever they could find until reliable cylindrical replacements became available in 1906, the latter first being tested in freight service with Consolidations. Atlantics built in 1906 were delivered with 9Rs. The A-4s of 1911 came with 7Cs.

Walschaerts vs. Walschaert

There has been much confusion over the years as to the name of the valve gear used on many of Union Pacific's steam locomotives. It is another case of similar names for two associated things, much like Promontory Summit, the site of the driving of the golden spike in 1869, versus Promontory Point, which is 30 miles south, and a point on Southern Pacific's Lucin Cutoff across the Great Salt Lake.

Gordon McCulloh wrote in July 2018:

I have long sought to have people get the spelling correct for this equipment!

Walschaerts is a far too common misspelling. If it was Walschaert's [possessive] it might be more correct, otherwise the use of Walschaerts [not possessive] is a far too common misspelling.

(View an advertisement from 1908, advertising the book "The Walschaert Locomotive Valve Gear, A Practical Treatise On The Locomotive Valve Actuating Mechanism Originally Invented By Egide Walschaerts")

Gordon also wrote in his article in The Streamliner, published by the Union Pacific Historical Society, Volume 4, Number 1, about Union Pacific's 2-10-2 locomotives:

Is it Walschaerts or Walschaert?

Many people believe the former to be the correct. The Encyclopedia of Railroads, by O.S. Nock, published in 1977 gives the following in its biography section.

Walschaert, Egide
"Born near Malines, Belgium, January 20, 1820; died St Lilies, Brussels, February 18, 1901, aged 81. Designer of the Walschaert valve gear used on steam locomotives. The family name was Walschaerts, but when Belgium became independent of Holland in 1830, the name was changed to Walschaert. He worked for the Belgian State Railways, and in 1844 he became foreman of the Brussels Midi station and works. In that year he also invented the valve gear, but, because he was prohibited by Belgian Railways from receiving royalties, the valve gear was patented in his name by M. Fischer, an engineer of Belgian State Railways."

Water Softeners

On December 31, 2006, there was a discussion about the wooden water "tower" at Tintic Junction on UP's LA&SL line southwest of Salt Lake City. The original message included an often published photo of UP Shay 59 at Tintic Junction, showing the structure in question, as well as the derrick tower of the adjacent pump shed.

The structure in question was a water softener and pump shed for the water tank at Tintic Junction, Utah. Although the wooden portion of the structure was removed during the 1950s after steam operations ended on the LA&SL, the steel tank remains in place as this is written in late 2011.

A drawing of Tintic Junction shows that the square structure to the south of the round water tank was a well house. The same drawing shows the round structure in the original photo as the water softener, and the photo shows that it was a wooden structure mounted on top of a vertical steel water storage tank. When the water softener was retired and removed, they left the storage tank in place, and it is still there today.

The Form 70 for 1946 shows two wells at Tintic Junction, with 48,000 gallons of storage. One well had a steam pump with 60 gpm capacity, and the other had an electric pump with 200 gpm capacity. The water softener was an "Infilco" type built in 1944, with a capacity of 20,000 gph. A quick review of the other districts shows that there were similar Infilco softeners at: (50,000 gph) Ogallala, Sidney, and Hanna; (12,000 gph) Lawrence, Salina, and Ellis; and (25,000 gph) Huntington. A check of photos might reveal similar wooden structure atop steel tank designs.

Wheel Arrangements

(Read more about the wheel arrangements of Union Pacific steam locomotives)

Whiting Test

In earlier days, crack detection was done with a wash made up of whiting compound, which was made up of chalk (calcium carbonate) and denatured alcohol. In the case of steam locomotive drive rods, the drive rod would be cleaned and wiped with kerosene (or mineral spirits, also known as distillate), which was then thoroughly wiped off. The Whiting Test is more easily accomplished at smaller roundhouses and shops than magnaflux testing, which required specialized equipment.

As part of the whiting test, after being wiped on the cleaned drive rod, the kerosene would be allowed to penetrate into any small stress cracks (after about 10 minutes). The kerosene is thoroughly wiped off and the "whiting" was wiped (or brushed) all over the drive rod and the alcohol and water allowed to evaporate, leaving only the whiting as a coating. The drive rod was then struck with a hammer. The vibrations caused by the hammer blows would cause the kerosene in the cracks to flow out, leaving dark lines and marks on the dried whiting, making the crack very obvious. In current times, in what is called non-destructive inspection, a "dye penetrant" is wiped on the item being inspected, and wiped off. Then a solvent that reacts to the dye is wiped on, and any crack becomes obvious by becoming a red line.

According to Union Pacific's Mechanical Instructions, G-2, General Superintendent MP&M, Omaha, Nebraska, July 1, 1947, whiting mixture is made of 1/2 pint of isopropyl alcohol, 1/2 pint water, and 1 pound of whiting.

The above mentions a Magnaflux test. This is a test in which a strong electro-magnet is attached to the drive rod, and turned on, causing a magnetic field. Very fine iron powder is then sprinkled all along the drive rod (especially at stress points). A crack will cause a break in the magnetic field and the iron powder will congregate at the crack, making the crack obvious by flowing along the lines of the magnetic field.

Wind Wings

Smoke Lifters -- Information about the use of smoke lifters ("Wind Wings") on Union Pacific steam locomotives. Includes a link to photographs and drawings.

(See also: skyline "smoke duct" on UP 815, above)

Wootten Fireboxes and Camelback Cabs

A Wootten firebox is a type of firebox that was very wide to allow combustion of coal waste, sometimes known as "culm", "boney", or "slack". The low combustibility of the boney coal meant that the fireboxes had to be much wider than a standard firebox. The firebox size meant that the locomotive crew rode the locomotives in camelback cabs mounted across the center of the locomotive boiler. The fireman was exposed to the weather as he fed the fire from the rear deck.

The following is taken from "The Engineer's Encyclopedia" by John G. Winton and William J. Millar, 1890, page cxxx:

The Wootten Firebox - One of the latest novelties in locomotive building has been achieved in rather an indirect manner by Mr. John E. Wootten, formerly Manager of the Philadelphia and Reading Railroad Company. It had occurred to Mr. Wootten that the enormous amount of slack or refuse coal, which is to he found around all coal mines, might possibly be utilized in locomotive fire-boxes, where the opportunity of an enormous draught is possible. He therefore patented a fire-box with a very large surface, indeed, so large that, whereas the fire-box in general use presents a surface of about twenty-six square feet between the wheels, Mr. Wootten, by lifting his fire-box above the wheels, was able to utilize a fire-box with about seventy-five square feet surface. There is a fire-brick arch or division, which is a very essential point in are design of the Wootten fire-box, and gives much of the success of the engines in getting the necessary draught for burning fine coal or slack. Besides the advantage that it gives of utilizing what was formerly worthless waste coal, these engines make steam freely, and haul the heavy express trains of the Union Pacific at a higher rate of speed than has ever before been attained on that road. The coal used is taken from the mines owned by the railroad, and is bituminous, though light, in its character. It is, however, successfully burned without any sparks, a result, of course, due to the enormous grate area, while the heat radiated from the arch fire-bricks or wall maintains an even temperature and insures complete combustion. The large area of the grate prevents any appreciable lifting of the fire, and the small pieces of live coal that are sucked up by the blast are burned on their way to the flues, owing to the high temperature of the brick arch. In the Wootten express engine, of which we give an illustration, it will be seen from the prospective view of the engine and tender, that the engines have two cabs, and thus the fireman is more efficiently sheltered from the weather than is usual on other engines. The severe climate of Nebraska and Wyoming in winter necessitates a very efficient protection for the men working the engines, and the arrangement shown, we are told, is found to answer well. The engine referred to above is one of the large class built by the Rogers Locomotive Works, of Paterson, New Jersey, for the Union Pacific Railway, from the designs of Mr. Clement Hackney, Superintendent of Motive Power of that line.

Union Pacific owned coal mines at Rock Springs, Wyoming, and their use of Wootten fireboxes was a move to use the waste coal, or "slack" coal from those mines. After a very brief time, it became apparent that Rock Springs coal and Wootten fireboxes did not mix well and the locomotives were rebuilt to use standard fireboxes and standard cabs.

As noted in the quote above, UP's Wootten 4-4-0s had two cabs. One for the engineer that straddled the boiler, and a partial cab that protected the fireman on the rear deck.

Union Pacific operated eleven 2-8-0 locomotives with Wootten fireboxes and camelback cabs, built by Baldwin in 1886. All 11 were rebuilt in 1893-1895 by UP at Omaha with standard fireboxes and standard cabs.

Union Pacific operated ten 4-4-0 locomotives with Wootten fireboxes and camelback cabs, built by Rogers in 1887. All 10 were rebuilt in 1891-1892 by UP at Omaha with standard fireboxes and standard cabs.

Type Quantity Builder Date
Date Rebuilt To
Standard Firebox
and Standard Cab
UPRy 761-770 4-4-0 10 Rogers 1887 1891-1892 UPRy 831-840 in 1891-1892; UP 831-840 in 1898; UP 944, 945 in 1915
UPRy 1301-1311 2-8-0 11 Baldwin 1886 1893-1895 UP 1301-1311 in 1898; UP 100-110 in 1915

(Read the Wikipedia article about Wooten fireboxes, and John Wooten, the man for which they are named)