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Union Pacific Steam Locomotives - General Notes

This page was last updated on November 24, 2024.

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(Listed alphabetically)

1896 Pacific Railway Hearings

As part of the investigations for the Pacific Railway Hearings of 1896 (formal name: "Pacific Railroads hearings before the United States House Committee on the Pacific Railroads, Fifty-Fourth Congress, first session, on January 1896. United States Congress."), the auditor reported the following after examining the account books (Volume 8, page 4437).

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:

First Numbers	Type	Quantity	Builder	Date Built	Later Numbers
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.

• 4004 25-C-105
• 4005 25-C-xxx (late design, probably a -400 series; builder's plate is missing) 
• 4006 25-C-107
• 4012 25-C-113
• 4014 25-C-115
• 4017 25-C-404
• 4018 25-C-119
• 4023 25-C-104

25-C Tender Classes

• 25-C-1, serial numbers 101-120, originally assigned to 1st series Big Boys
• 25-C-2, serial numbers 201-220, originally assigned to 2nd series Challengers
• 25-C-3, serial numbers 301-325, originally assigned to 3rd series Challengers
• 25-C-4, serial numbers 401-405, originally assigned to 2nd series Big Boys
• 25-C-5, serial numbers 501-520, originally assigned to 5th series Challengers

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

Tender Number	Date Built	Fuel	Removed From	Locomotive Class	Locomotive Type	Date Locomotive Vacated	Date Tender Vacated
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)

Built-Up Frames

Gordon McCulloch wrote the following in an email dated January 13, 2015.

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.

(Read more about the Common Standard locomotives on Union Pacific)

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 Arrangement	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)

(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:

First Numbers	Type	Quantity	Builder	Date Built	Date Rebuilt To Simple	Later Numbers
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.

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

(View the full roster data for OSL 670 and 671)

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:

First Numbers	Type	Quantity	Builder	Date Built	Date Rebuilt To Simple	Later Numbers
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.

Feedwater Heaters

Elesco was one of the best known brand names for feedwater heaters, with "Elesco" being the pronunciation of "LSCo", for Locomotive Superheater Company.

The following comes from "Perfecting The Steam Locomotive," by J. Parker Lamb, 2002, page 85.

Five of UP 5000-class-2-10-2s were equipped with Elesco EK-50 tube-type feedwater heaters: UP 5019-5023 and 5040. UP 5040 was the only one of the five that had its Elesco feedwater heater mounted high on its smokebox. The other four had their feedwater heater mounted low on the pilot deck.

The following comes from "A History of Union Pacific Steam" by Gordon McCulloch.

Additional information from Gordon McCulloch's book.

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)

Lima Proposed Locomotives

Research in Lima Locomotive Company records in the 2013 period found two proposed locomotive designs for Union Pacific. One was for a Lima version of what later became Alco's FEF-2 4-8-4. The Lima proposal is dated January 20, 1939, and is shown on Lima Card 976-A-92. It shows that the Centipede tender was proposed by that time.

The second proposed design was for a 2-6-6-4 articulated, shown on Lima Card 976-A-93, dated February 24, 1939. Unfortunately, the details of this proposed design was not as complete as the proposed 4-8-4, showing only the minimum boiler outline, the firebox outline, no cab, and only the wheels of the proposed tender.

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.

Mars Signal Lights

Photos show that UP began applying Mars signal lights to its FEF-class 4-8-4s in late 1946 or early 1947. This date coinsides with Mars lights also being applied to the City of Denver Streamliner and to the E6 Streamliner locomotives in the same 1946-1947 period.

(Read more about the application of Mars signal lights to UP's diesel locomotives, including some history of the Mars Signal Light Company.)

The model of Mars Signal light used on UP's FEF-class steam locomotives was the Model R-250. The version used on the diesel locomotives was the Model WR-5000.

The following comes from Dick Harley:

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.

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.

Rotating Coupler Pilots

Based on a review of photographs, the rotating coupler pilots used on Alco steam locomotives delivered to Union Pacific were unique. Slotted doors were the standard, begun with the 4000s. UP mechanical images refer to them as "Pilot Doors." Thus far research has not yet found any railroad record of the change when the slots were eliminated on replacement doors, but it appears to have happened in about 1949. The arrangement with slots remained fairly common, but with the coupler out, the doors are hidden. Some CSA Challengers had their built up front frame replaced by a cast steel loco-bed and these also had the same cast integral pilot with slotted doors. UP 3835 got the late replacements with no slots by 1954. Incidentally, the CSAs with locomotive beds also had roller bearing axles on the locomotive beds, the same as was standard on the FEF, 4884 and 4664 classes.

Steam locomotives were not equipped with any type of draft gear on their front couplers, which explains how and why a rotating fron coupler would be able to function.

More research found late UP Alco pilots and their modifications in Mechanical Department images dated February 15, 1949. A modification patented by Buckeye Steel Company was adapted to the Commonwealth Steel Company Retractable Coupler and Pilot Door Assembly. The purpose for the change was a "Modification to Reduce Front Coupler Swing From 19 to 13-inches." With that reason given, it seems likely to have been a universal alteration but suitable well lighted post 1949 frontal photos were not available when the research was done.

Affected locomotive classes were the 3800- and 3900-class Challengers, the 4000-class Big Boys, and the the 3800-class CSA-1-2 with front locomotive beds.This modification was most certainly not made without a specific reason. In fact, it was frequently made to damaged pilots, especially in the sense of FEF-2 and FEF-3. Photos indicate it was more universally seen on the Big Boy and 4-6-6-4 classes, whether due to the intention of reducing coupler swing or not. But it was not something effected in the sense of any formal modification program.

The 800-class FEF-2s had a drop coupler and to date, research has not yet found evidence they ever got a swing coupler.

The only FEF-3 found with this modification that eliminated the slots in the coupler door is the 844, done between 1954 and 1958.

Perhaps you have some other FEF-3s that you know of, my photo catalog is somewhat limited.

The most likely reason for the chnage was too many front coupler assemblies were getting damaged by helpers coupling-on to road locomotives, which would explain why so many were modified with the Buckeye front couplers.

As far as the front coupler design being adequate, Union Pacific Mechanical Engineering was probably one of the most conservative in the industry and surely would not have used them if they could not handle the load of an entire train when a helper was used. Big Boys had plenty of Sherman Hill helpers in the 1950s, and Buckeye Steel sold a lot of that patented design coupler.

Close-up details photos in Kratville's "Big Boy" show that the entire pilot casting was one piece. The pilot casting was bolted to the flat areas cast into the front engine bed, showing that 28 bolts were used.

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)

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 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

• UP 2227 (1939)
• UP 2524 (1940)
• UP 2532 (1936)
• UP 2557 (1954)

Large Flat Plow

• UP 2226 (1950)
• UP 2230 (1951)
• UP 2262 (1955)(1956)
• UP 2263 (1956)
• UP 2298 (1950)
• UP 2491 (1951)
• UP 2519 (1954)
• UP 2548 (1953)

Large Curved Plow

• UP 2548 (1953)

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

Specifications

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):

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:

From the 1946 rule book:

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:

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

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:

(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:

(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:

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

• Number D34765, applied for on May 31, 1901, and published on July 9, 1901. It had a 14 year expiration period.
• Number 681760, applied for on May 31, 1901, and patented on September 3, 1901.
• Number 747280, applied for on October 30, 1902, and patented on December 15, 1903.
• Number 771590, applied for on November 20, 1902, and patented on October 4, 1904.
• Number 781699, applied for on September 12, 1904, and patented on February 7, 1905; this patent showed a tank design that had a flattened shape. Union Pacific did not have any tenders with this non-cylindrical design.
• (Structured Google search showing all five Vanderbilt patents)

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):

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:

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:

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:

Patent No. 7,267 awarded to John E. Wootten on August 15, 1876.

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 UP-owned 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.

First Numbers	Type	Quantity	Builder	Date Built	Date Rebuilt To Standard Firebox and Standard Cab	Later Numbers
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 Wootten fireboxes, and John Wootten, the man for which they are named)

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