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Union Pacific Steam Locomotives

This page was last updated on January 24, 2012.

(Return to UP Steam roster index page)

General Information

(Based on an original completed in April 1996; updated in August 1998; with additional updates starting in March 2009)

Steam Locomotive Index

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 UP's locomotive folio diagram sheets, in the Accounting Department's Form 70 "List Of Agencies, Stations, Equipment, Etc.", and on the locomotive cab sides.

The original classes started in the Harriman Common Standard era, and were first shown on painting and lettering sheets dated 1904. These were the CS classes such as MK-1, MK-2, etc., where a wheel type was designated (C for Consolidation, and MK for Mikado, etc.), with a trailing sequential number. These designations were not used on the locomotives' cab sides, and apparently went away during the 1930s.

The cab side lettering instead included the classes without the sequential number, using the more common class and driver size combination. An example would be the Common Standard Mikados MK-1 and MK-2, both becoming MK-57, or the WWII era MacA-57.

The cab side lettering started in 1937. (see Jim Ehernberger's article in The Streamliner, Volume 8, Number 1)

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. (click here for more information)

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.

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 Union Pacific 800 series of the 1880s and 1890s, and the OSL 500s of the late 1890s are the most obvious and most problematic examples.

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. This roster uses the best available weights for UP's locomotives, drawing from as many sources as may be available.

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.

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

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

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
ORR&N 340-344 2-8-0 5 Baldwin 1902 1910-1919 OWRR&N 725-729
UP 1508-1521 2-8-0 14 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

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 its own coal mines at Rock Springs, 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.

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

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

Congdon Extensions and Smokestacks

Steam locomotives soon became well known for starting fires along the railroad lines. To prevent line side 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 the locomotive front extension in 1864 (U. S. Patent 43,898, dated August 23, 1864) (Google patent search), 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 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 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. (Google patent search)

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 1885/86 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)

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

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)

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.

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.'

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.

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 146,800 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.

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