Three Cylinder Steam Locomotives

As far as I know, there are only five surviving 3-cylinder rod steam locomotives in the United States (this, of course, does not include all of the 3-cylinder Shay type locomotives). They include:

Southern Pacific 4-10-2 Number 5021

Souther Pacific 3-cylinder 5021 This is the only surviving Southern Pacific three-cylinder 4-10-2 (out of 49). The first of this type was built in 1925 by ALCO. The first axle is cranked to allow clearance for the center connecting rod on the second axle. The Southern Pacific named this wheel arrangement after their own name (Southern Pacific). The Union Pacific also had locomotives (10) of this wheel arrangement (none survived). They named them "Overlands". This locomotive has 63 inch drivers. With its three cylinders, it could develop 4,100 HP. Its top speed was 60 MPH. They were used for both freight and passenger service over Donner Pass until it was determined that they were too rigid for the curves on that line. 5021 is in maintained in excellent condition.

Union Pacific 4-12-2 Number 9000

Union Pacific 3-cylinder 9000 The 9000 recently had the majority of the asbestos removed (everywhere except in the cab). The boiler jacket is off and set aside for re-use or fabrication of new pieces, as needed.

The UP 9000s had two outside 27"x32" cylinders driving the third set of drive wheels and a third 27"x31" cylinder in the center driving the second axle. The 9000s had 67 inch drivers. They were constructed with "blind" driver tires on the third and fourth axles, that is, without the usual flanges, in an effort to promote easy passage through tight curves. The blind drivers were found to be unnecessary as tests of the first 4-12-2 proved the usefulness of the lateral motion devices fitted to the first and sixth driving axles. There was an attempt to see if they could negotiate the Oregon Short Line in the Mountains of Oregon. The test failed and they were returned to the prairies of Nebraska for which they were designed in the first place.

There is an extremely accurately detailed model of the UP 4-12-2 available for general viewing at the Schenectady Museum, in Schenectady, NY. The model is in a section of the museum called the Schenectady Heritage Area. The model provides an excellent view of the lateral motion devices fitted to the first and last driving axles, spring rigging, main and side rod designs, cylinder configurations, valve gear arrangements, etc. The model is covered by a clear plexiglass cover which allows for viewing but no touching.

1st Axle Clearance Crank?

There has been some disagreement on whether or not the first drive axle on this class of locomotives has a 'clearance crank'. The typical configuration for a three-cylinder steam locomotives is to have a cranked first axle so that clearance is provided to the connecting rod that is connected to the second set of drive wheels. The Guide to North American Steam Locomotives by George Drury states that the first axle is cranked. I have also received e-mail which stated that the first axle has a crank. However, I have been in contact with John E. Bush who was the co-author of an excellent reference book on these locomotives (Volume 2 of The Union Pacific Type by Kratville and Bush). This book has several photos which show quite clearly that it does not have a 'clearance crank' on the first axle. Instead, it explains, the builders added 18 inches to the distance between the first two axle centers, thus precluding the need for a 'clearance crank' on the first driving axle. This has been verified by Barry Koeb who is the R&LHS member responsible for the UP 9000 who has been inside the frame of the 9000. I am now convinced that the first axle on this class of locomotives did not have a crank. The last time I was in LA, I tried to look under 9000 and photograph the first axle. However, the front of this locomotive is so tightly packed that I could not see the front axle let alone photograph it.

In summary, the 9000's designers wanted to avoid having to put a crank in the axle of driver number 1. So they did the following things:

Driver "Quartering" and Valve Gear

I have been told that the designers had to keep the quartering at equal 120 degree angles partially for centrifugal mass balancing reasons. However, if the inside cylinder is inclined at say 7°, it would normally be necessary to set the cranks at 120°-127°-113° to preserve the torque distribution. Apparently, this was not necessary for the 9000s. The #2 driver has an enormous inside steel crank/counterbalance assembly that has to spin in concert with, and balanced to, the outside main rods. (One hundred and twenty degrees is the quartering angle listed in the book "Union Pacific Type, Volume 1" and confirmed by one of the co-authors, John Bush.) It is suspected that one of the reasons the Baldwin #60000 used a 90°-135°-135° configuration had to do with it being a compound locomotive, with the center cylinder receiving high-pressure boiler steam, and the outer cylinders receiving the low-pressure steam from the center cylinder. And according to John Bush, the locomotive had "a very interesting" outside valve gear design. The original valve gear used a conjugated assembly that synthesized inner cylinder valve gear motion from the outer valve gear on either side of the locomotive.

"Lopping" Exhaust

Many have pointed out the "lopping" exhaust rhythm one hears in recordings of the 9000 class. The sound may be the result of a number of factors: When released from shops with running gear trammed "to dimension" and valves set correctly, a 9000 had a very even 1-2-3, 1-2-3 beat. All of the main dimensions were the same for the outside and inside cylinders (except that the inside cylinder was one inch shorter) and valves and when everything was right they were square like any engine, only with six exhausts per revolution. Like other power, the unevenness developed as miles grew, and in particular as maintenance forces allowed the inside main rod to languish! If you've heard Howard Fogg's recordings of 9009 on his great album "The Big Steam" and think thats what a 4-12-2 regularly sounded like please consider it as virtually totally unrepresentative of their sound. That engine was horribly out of time and in fact would scare one at speed. When badly out of dimension, engines can begin working against themselves.

Other Long, Rigid Wheelbase Steam Locomotives

The UP 9000s had the longest rigid wheelbase of all steam locomotives in the United States. However, there were a few other countries with equally impressive locomotives. Bulgaria and two groups of 2-12-4Ts, Indonesia had a few 2-12-2Ts. Russia built one 4-14-4 (classified as a 2-7-2). It made one demonstration run during which it tore the track apart -- it was stored and later scrapped. It was designed shortly after a group of thirty young Soviet engineers toured the USA in 1930 and 1931. They saw the last of the Union Pacific 4-12-2s being built by Alco's Dunkirk New York shop. Steam locomotive historians consider the Soviet 4-14-4 to be an example of the Russian's trying to outdo the Americanskiies. The Russians learned many useful things during their tour, and did develop a successful 2-10-2 freight engine and a 2-8-4 passenger locomotive using ideas they picked up from Alco and Baldwin.

4-14-4 Photos:

Other UP 9000 Web Pages

Alton & Southern 0-8-0 12

Alton & Southern 12 This Alton & Southern 0-8-0 is located at the Museum of Transportation in St. Louis, MO. It was built by ALCO in 1926 and cost $57,598.20. It ran up 622,626 miles in service and was donated to the museum in 1948. Here is the locomotive data from its builders photo:

American Locomotive Company
New York
Class 080 S 243, "Three-Cylinder"Road Number 12
Built for the Alton & Southern
Gauge of TrackCylindersDriving Wheel DiameterBoilerFire BoxTubes
DiameterStrokeInside DiameterPressureLengthWidthNumberDiameterLength
4'-8 1/2"22"28"57"76"200 lbs96"84 1/4"239
5 1/2"
Wheel BaseWeight in Working Order - Pounds
DrivingEngineEngine & TenderDrivingEngineTender
16'-4"16'-4"54'-6 3/4"242500242500169400
FuelEvaporating Surfaces, Square Ft.Superheating Surface Square Ft.Grate Area Sq. Ft.Maximum Tractive PowerFactor of Adhesion
KindTubesFluesFire BoxArch TubesTotal
Soft Coal199187118623307174056.160600 lbs4.0
Tender Type 8-Wheeled.Capacity Water 9000 galsFuel 14 tons
Order No S-1560
September, 1926

London & North Eastern Railway 4-6-2 60008

London & North Eastern 3-cylinder 60008 This three cylinder Pacific, named Dwight D. Eisenhower, is displayed at the National Railroad Museum in Green Bay, Wisconsin. It was originally named Golden Shuttle but was renamed in late 1945. It was built by the LNER as the A4 class, introduced in Sept 1935. There were 35 in the class. When British Railways was formed in 1946 by the amalgamation of four "Groups", there was some number duplication on locomotives. Block numbers were allocated the four former groups of locomotives. Former LNER locos were numbered in the series starting at 60000. That is how 60008 (formerly number 8) came about.


Boiler max. O.D.:6' - 5"
Grate area:41.2 sq. ft.
Heating surface firebox + combustion chamber:231 sq ft
Total evaporative surface:2576 sq ft
Length between tube plates:17' - 11.75"
Superheater surface:750 sq ft
Operating pressure:250 psi
Cylinders:(3) 18.5" dia by 26" stroke
Valve Gear:Walschaerts with Gresley derived motion for inside cylinder
Piston Valves:9"
Steam lap/Max travel:1 5/8" / 5 3/4"
Locomotive Weight:102 ton 19 cwt
Tender Weight:64 ton 3 cwt
Tender capacity:8 tons coal, 5000 gallons water
Axle weight:22 tons
Data taken from "British Locomotive Classes" Promotional Reprint Company 1996. First published by the Locomotive Publishing Company 1945 entitled Modern Locomotive Classes. The locos modified during the war, with sections of the streamline casing removed, so the weights may be wrong for your engine. Further, some engines had double chimneys with Kylchap exhaust systems. The record breaking engine Mallard (126 mph) was so equipped.

Baldwin Demonstrator Number 60000

With the year 1926 came an outstanding event in Baldwin's history, for at that time the Works was ready to build its sixty-thousandth locomotive. To symbolize this event President Samuel M. Vauclain planned and built a huge three-cylinder compound, high-pressure locomotive. It was of the 4-10-2 type and closely resembled engines with this wheel arrangement on the Southern Pacific Railroad. To safely accommodate the high boiler pressure of 350 lb. per square inch, a water-tube firebox was used.

From the book The Locomotives that Baldwin Built by Fred Westing

Baldwin 3-cylinder 60000 Built as a Baldwin demonstrator in 1926, this locomotive was used by various railroads around the country to show some of Baldwin's latest ideas. It was numbered 60000 to commemorate the 60,000th locomotive to be built by the Baldwin Locomotive Works. It ran successfully on either coal or oil as fuel. It also attained the highest power ever developed up to the time on the Altoona test plant, namely, 4,500 horsepower. This, at the time, exceeded the plant's capacity and restricted attempts to obtain greater power with additional tests. It has several features which made it unique: NOTE: If you look carefully under the smokebox front, you will see the center high-pressure cylinder and steam chest. This cylinder is angled downward to the back. The piston is connected via a crank to the second set of drivers.

The numbers 60000 appear on the cab side, and on the number boards and headlight of the engine. The tender lettering reads THE BALDWIN LOCOMOTIVE WORKS. The tender is a Vanderbilt with a short coal space and 6-wheel trucks. Here are a few more specifications on the 60000:

Although there were not any serious problems with it, the railroads rejected it because they found it overly heavy and complex and were wary of most of its features. Also, the 4-8-4 was quickly becoming the ideal high-speed, heavy freight and passenger locomotive. With only 100,000 miles on it (very little for a steam locomotive), it was returned to Philadelphia in 1928 and stored until 1932 when it was donated to the Franklin Institute Science Museum in Philadelphia, PA.

It is on display there today in the basement on a short piece of track. A hydraulic system is used to move the locomotive back and forth about fifteen feet. The demo was once propelled by a worm gear. It was changed over to a hydraulic system in the mid 1970s. By that time, the bearings in the drivers had become egg shaped, supposedly because of all the reversing, and some BLH retirees figured out how to replace them. The distance traveled inside the museum was staggering for such a short trip: conservatively, 30 ft/trip x 2 trips/demo x 5 demos/day x 360 operating days/yr = about 20 miles/yr, or about 400 miles in reverse by 1980.

Other Pages on the Baldwin 60,000

Other 3-Cylinder Steam

Baldwin built a batch of 3-cylinder pacifics for the EFCB (Central of Brazil) in 1927. They were broad gauge machines (5ft 3") (Brazil Central had both 5'-3" and Metre gauge lines). One of these is preserved in working order and operates about once a month. It is stored at the Museum of the Immigrants in Sao Paulo.


3-Cylinder Steam Reference