Here are a 7 articles on Railroading by Jack Herris, all articles are copy-write protected and not to be copied or altered in anyway without written permission by author

Fun Time 1
© Jack Herris, 2008

Having fun not only makes you happy, it makes you healthier too. For your health, longevity, and enjoyment, it is better to retire to something rather than just retire from something. Even better, you don’t need to wait until retirement to find a fun hobby; I didn’t. In fact, I may have too many hobbies. But let’s talk about some things you may find interesting.

Like many men of the Boomer generation, as a child I got a train set for Christmas and had a lot of fun with it before work, college, family, and other interests took my time and attention. A few years ago, while searching for a train set as a Christmas present for someone else, my dormant train interest was revived and I got back into it in a much bigger and more focused way.

Why Trains?

But first, why would one be interested in trains? Railroads changed the world and have had a dramatic impact on our national history and culture. It is not much of an exaggeration to say that trains built this country, especially the West; the basic shape and location of our towns and cities was once determined by where the railroads ran. For decades railroads were America’s glamour industry and employed millions of people over the years. So the cultural, economic, and historic impact of railroads was dramatic. But most of all, exploring the railroads in different ways is fun, and that is the real reason to do it. So what are the possibilities?

There are many different activities for people interested in trains. For some, museum visits are great fun, and the California State Railroad Museum ( in Sacramento is one of the very best. Others want to work and play with full-size trains, and the Pacific Locomotive Association ( does so in Niles Canyon, near Fremont, CA, where you can ride these historic trains. Or you can get your own railcar and tour the rails with the Pacific Railcar Operators ( based in San Jose, CA.

Various railroad-oriented tours are also available, and I personally enjoyed a wonderful tour put on by Trains Unlimited Tours, LLC ( Those with a serious historical interest have a tremendous number of railroad-related books and videos available. Finally, and perhaps most well-known, one can model trains. Railroad enthusiasts in Silicon Valley are especially fortunate to have The Train Shop, near Valley Fair (1829 Pruneridge Ave., Santa Clara, CA, 408-296-1050) as a resource. The Train Shop has a huge railroad book section as well as model railroading supplies for all scales, and they sell most products at a discount.

So, if any aspect of railroading is of interest, you have many local resources to explore to help you determine if you want to pursue this interest further.

Next time we will discuss the model railroading aspect in more depth.

Fun Time 2
© Jack Herris, 2008

With some justification model railroading is billed as “the world’s greatest hobby.” So how do you get started?

First, there are a number of different sizes, or scales, of model trains to choose from depending on your goals and the amount of room you have. And real railroads have different gauges, or distances between the rails.

Real Railroads

Real railroads have been made to different gauges, but standard gauge in North America and Europe is 4 feet 8.5 inches between the rails. Amazingly, this distance appears to be traceable back to the distance between the wheels of Roman war chariots! There are also several different narrower gauges, with 3-foot gauge perhaps the most commonly used in America. Narrow gauge is cheaper to build than standard gauge and is used primarily for remote mountain railroads and specialized logging and mining operations where tighter turns and clearances dictate smaller equipment, and where cost is especially important.

Model Railroad Sizes

Model trains are made in different sizes, or scales, for different purposes. Here we need to distinguish between the scale, or proportion of model size to actual size, and the gauge, or distance between rails. For most common scales this is somewhat academic because there is one scale corresponding to one gauge, so we can use the words scale or gauge interchangeably, except for the difference between modeling standard gauge or narrow gauge railroads. The one exception is the first gauge we will discuss, G.

The largest common gauge, G, which many think of as garden scale but really comes from the German gross for big – it was developed in Germany – is most useful for those who want to put a train layout outside in their garden. This gauge is the only gauge whose track and equipment are designed to survive outdoors, and uniquely offers the possibility to combine model railroading with gardening. For this reason, G is growing rapidly in popularity with many couples. G gauge runs on track with 45mm, or about 1.75 inches, between the rails. G is more correctly known as a gauge because the distance between the rails, or gauge, is standardized but different scales of model trains, from 1:20.3 to 1:32 scale, are run on it. For example, a narrow gauge train that runs on G gauge track could be 1:20.3 actual size, while a standard gauge train that runs on G track would be 1:32 actual size. This is the only common model railroad gauge in this situation. G gauge is now often used for Christmas train sets too.

The next smaller common size is O gauge, or 1:48 actual size (1/4 inch on the model = 1 foot on the actual, or prototype, item). In the case of O gauge, both the scale (1:48) and the gauge (32mm for standard gauge) are fixed. Standard O gauge track has a 32mm gauge; narrow gauge O scale, or On3, runs on standard HO track of 16.5mm gauge (see below). Most people are familiar with this scale from the well-known Lionel toy trains, which feature three-rail track instead of two rails like real trains. Of course, there are other O scale vendors in addition to Lionel, including many who make O scale trains that run on more realistic two-rail track. O scale trains have a wonderful presence that smaller scales can’t match and allow much detail to be visible, a plus for scale modelers. Their main disadvantage is the relatively large amount of space they require for a good layout.

The next smaller common size is S gauge, or 1:64 actual size (3/8 inch on model = 1 foot on the prototype). S gauge was developed as a more compact size that still offered a lot of detail to be easily visible. The old American Flyer trains running on two rails are S gauge, and many modelers who like narrow gauge railroads model in S scale. Standard S scale track has a gauge of 22.42mm; Sn3, or S scale narrow gauge, with the 3 indicating the prototype had 3-foot gauge, runs on special track of 14.28mm gauge.

The next smaller common size is HO, originally conceived as Half O but actually 1:87 actual size rather than the 1:96 one might expect from its name. HO is by far the most popular scale in the world because it is a reasonable compromise between a size large enough for detail to be visible but small enough to enable a reasonable home layout to be built. Currently about 76% of all model railroaders model in HO, and it therefore has the economies of scale to deliver the lowest prices and greatest variety of products supported by the widest variety of vendors. Standard HO track gauge is 16.5mm, and HO narrow gauge track is generally 12mm, representing about 3 foot 6 inches actual size, just a little larger than typical for American narrow gauge.

The next smaller common scale is N, which is 1:160 actual size. N track is 9mm gauge, and the scale’s name stems from Nine millimeter gauge track. N is the most popular small scale and, while making model details difficult to see, enables the hobbyist to create a useful track layout in very reasonable space. Some modelers even build their N-scale layout on an old door!

Finally, Z is the smallest commonly available scale, and at 1:220 actual size makes even N scale look large. With Z the goal is clearly to model the most railroad in the least space for an operating layout.

There are other model railroad scales, but the ones listed are the most common and the ones I would recommend in most cases.

What Size Is Right for You?

If running trains on a layout is most important to you, and having the most interesting layout in a convenient space is therefore a priority, then HO or N scales are recommended. On the other hand, the smaller the scale, the more challenging it is to see them and to get the models to run well. If making exquisite models of locomotives and train cars is your goal, the larger scales are recommended so the detail is more easily seen. And if you have enough space for layout, it is easier to get the larger scales to run well. Finally, if you want to build an outdoor layout, G gauge offers the only equipment that is designed to withstand the outdoor environment, including protection from the sun’s UV rays.

HO is my personal choice as the best compromise between visible detail, good running on layouts of practical size, and the widest variety of models at the lowest prices. However, before you decide, go see some operating layouts and talk to the people there. There are a number of model railroad clubs in your area that are open to visitors.


q  For more information on model railroad scales:

q  The South Bay Historical Railroad Society is located in the Santa Clara Depot, has both HO and N scale layouts, and is open to the public Tuesday evenings and Saturdays:

q  Silicon Valley Lines is a large HO club in San Jose:

q  The Bay Area Garden Railway Society is very active in G gauge and has an informative website:

q  The World’s Greatest Hobby site has lots of information, including ways to search for public layouts to visit:

q  The National Model Railroad Association has an extensive website:

Fun Time 3
© Jack Herris, 2008

Last time we explored the concept of size or scale for model trains. This time we want to look in more depth at what can you do with model trains.

Different aspects of model trains include focusing on static models, such as having a collection of model locomotives, and operating trains, which has a number of facets.

Static Models

With static models, the focus is on both the accuracy of the models and the theme of the collection. For example, do you want to have a collection of locomotives? If so, which ones? Do you prefer steam locomotives or Diesels? Do you want to model the equipment of a particular railroad? And what size do you want to collect and display?

If you just want a static collection of locomotives, my suggestion is either HO or O scale. HO offers the most variety, typically is lower cost, and can reside in a much smaller space. O scale models are much larger and are easier to see and super-detail. In addition, the larger O scale models are more impressive than HO; they have a presence the smaller scales cannot match. While HO is my personal choice, I have seen wonderful O scale models that were breath-taking, and have resolved to convert to O scale if I ever win the lottery so I can afford a large enough layout!

Operating Models

Operating model trains are the most popular because they do something and are fun to play with. Here the main choices range from O to N, with HO being the most popular. O scale looks wonderful but requires a lot of space. N scale enables you to put a lot of layout in a small space, but these trains are harder to see and a little more challenging to make run smoothly because they are more affected by track imperfections, etc. Again, HO is the most popular compromise.

The next thought is, what do you do with operating trains? Do you just run them around the layout or do you do something more focused? While those new in the hobby like to just run trains, many experienced model railroaders attempt to run their layouts like a section of a real railroad. This may involve bringing in an inbound train and breaking it down into individual cars that are ‘spotted’ at specific industries, then making up an outbound train from those cars and others already there. This activity has a purpose and keeps you interested in operating the model railroad. More advanced modelers run a model of an actual railroad at a selected time in history and run examples of trains from an actual historic operating schedule! Here a ‘fast clock’ is sometimes used to cram a 24-hour day into a four-hour operating session.

Should You Join a Club?

Another question that comes up is, should you go solo or join a model railroad club? After purchasing some locomotives and rolling stock on my own, I finally joined a club and I recommend it for a number of reasons, especially if you want to operate trains. First, you can immediately run some trains and have fun right away. Second, you will learn a lot from the more experienced members. Third, you will make a lot of new friends. Fourth, you will more quickly learn what aspects of the hobby appeal most to you. Some modelers like great models to display, others want to run trains, others like to model structures, scenes, or scenery, etc. Finally, you can do all this without spending a lot of money!


q  The South Bay Historical Railroad Society is located in the Santa Clara Depot, has both HO and N scale layouts, and is open to the public Tuesday evenings and Saturdays:

q  Silicon Valley Lines is a large HO club in San Jose:

q  The Bay Area Garden Railway Society is very active in G and has an informative website:

q  The World’s Greatest Hobby site has lots of information, including ways to search for public layouts to visit:

q  The National Model Railroad Association has an extensive website:

Fun Time 4
© Jack Herris, 2008

Last time we explored what you can do with model trains, such as creating a locomotive collection for display or operating model trains on a layout. This time we will look at what historical era might be most interesting to you and which railroads you might want to model.

What Era?

You may want to consider is what historical era interests you most? While you can model anything you want, you may want to focus on a theme, regardless of whether you are creating a locomotive collection or an operating layout. For example, you could decide to build a locomotive collection showing the evolution from early railroading until the present, or you could build a collection of modern steam locomotives or first generation Diesels. Or you could model passenger trains for a specific railroad or era.

Steam locomotives changed the world by making railroads practical, and reigned supreme until the end of WW2. This period was the golden age of railroading due to the importance of railroads both economically and culturally.

Diesel locomotives entered switching service in the mid-1930s and by the late 1930s were developed enough to haul both streamlined passenger trains and freight trains. Once developed to adequate power and reliability, Diesel locomotives quickly manifested a number of economic and operational advantages over steam locomotives. Probably the most important was the greatly reduced maintenance requirements of Diesels, which enabled the railroads to cut costs by eliminating large numbers of maintenance workers. Diesels also were at least twice as fuel efficient as steam locomotives and produced much less pollution. In addition, Diesels used almost no water – very significant in the dry West, had high starting tractive effort to start long trains in motion, and, if properly equipped, were able to use ‘dynamic brakes’ to maintain safes speeds down hills. The dynamic brake was the ability of the Diesel to use its traction motors as generators when being pushed downhill by the weight of the train; the power generated electric current that was directed to banks of resistors in the Diesel and cooled by large fans. Particularly in mountainous regions, this was a significant operational advantage.

During WW2 the War Production Board controlled what locomotives were built; Diesel locomotives were especially hard to obtain due to production of submarines and other war material that competed both for the raw materials and the Diesel engines and accessories. So, during WW2 many railroads that wanted Diesel locomotives had to settle for steam locomotives instead. The incredible amount of war traffic, coupled with the deferred maintenance, wore the railroads and their rolling stock and locomotives out. After WW2 ended the great steam to Diesel transition era began; worn out steam locomotives were rapidly replaced by new, more economical Diesels. By 1959 the mainline steam locomotive in the United States was history.

In addition to the evolution of locomotives, the types and sizes of railroad cars has also been in a constant state of evolution. Passenger cars evolved from wood construction, which was very dangerous in accidents, to partial steel then all steel construction, and finally, in the late 1930s, to lightweight, streamlined cars. Freight cars evolved from wood construction to wood and steel and finally all-metal construction. Along the way freight cars grew larger and new types were introduced.

It may come as no surprise that the steam to Diesel transition era is easily the most popular era with modelers because it offers the greatest variety of locomotives, including all but the earliest steam locomotives and early, first generation Diesels. This is the era I chose to model because it gives me the most choices in locomotives. Although as a modeler I prefer the personality of large steam locomotives to Diesels, I am also somewhat interested in Diesels, especially the large and unusual Diesels of the 1960s and 1970s and their relatively short-lived turbine cousins. So I do not completely limit my modeling to the transition era. It is also possible to model much earlier eras, but far fewer models are available for the railroads of the 1800s. Furthermore, the largest, most modern steam locomotives did not appear until the 1920s. So modeling an era prior to the 1920s eliminates a lot of interesting locomotives, but the smaller locomotives used prior to the 1920s are well suited to a small layout.

The modern era, with all Diesel locomotives, is also popular. Model Diesels are generally less expensive than model steamers and, similar to their prototypes, are easier to keep running smoothly. Furthermore, you can look at an existing railroad today, take photos, and model it. On the other hand, modern technology is resulting in an ever-increasing supply of high-quality, smooth-operating model steam locomotives, so your modeling choices now are greater than ever.

What Railroads?

While the era you model is a personal choice, certainly, the railroad – or railroads – you choose to model is an even more personal choice. For example, the mighty Pennsy, the Pennsylvania Railroad, was once the world’s largest railroad and is still very popular with modelers, especially those who live in the area it served. You may be most interested in the railroad that served the area where you grew up. Or, like me, you may be more interested in the mighty railroads of the West and the mountain ranges and other difficult terrain they had to battle to deliver the goods – and passengers.

Whatever railroad you choose, most likely there is a book, perhaps a lot of books, on that railroad. And most major railroads, even if now ‘fallen flags’ (that is, bought by other railroads and no longer existing under their former name) have historical societies devoted to them.


Railroad Books & Videos:

q  New Railroad books:

q  Out of print railroad books:

q  New railroad books and videos at a discount:

q  New railroad books and videos at a discount:

q  Model Railroader Magazine:

q  Back issues of railroad magazines and out of print books:

Railroad Historical and Technical Societies:

q  Southern Pacific Historical & Technical Society:

q  Union Pacific Historical Society:

q  Santa Fe Railway Historical & Modeling Society:

q  Feather River Rail Society:

q  Pennsylvania Railroad Technical & Historical Society:

q  National Railway Historical Society:

q  California State Railroad Museum:

q  More than 5,000 railroad links:

q  Index to Railroad Historical Societies:

Fun Time 5
© Jack Herris, 2008

Last time we explored what historical era might be most interesting to you and which railroads you might want to model. Now let’s discuss some practical model railroad issues.

Where Do You Buy?

As mentioned in the first column in this series, railroad enthusiasts in Silicon Valley are especially fortunate to have The Train Shop, near Valley Fair (1829 Pruneridge Ave., Santa Clara, CA, 408-296-1050) as a resource. The Train Shop, one of the largest model train hobby shops in California, has a huge railroad book section as well as model railroading supplies for all scales, and they sell most products at a discount. Furthermore, they have a good supply of the more specialized model railroading supplies for the more advanced modeler.

Of course, no brick and mortar business can stock everything. As you might expect, there are a number of vendors with a large on-line presence that offer a wide variety of products. And, if you are looking for items that are currently out of production or used, then eBay is a good source. In fact, eBay is the main marketplace for many of the more specialized items like brass locomotives.

Mass Produced and Specialty Products

Which brings us to the discussion of small production run, specialty items compared to mass production items. Certainly, mass production products, typically made mostly of plastic, have substantially improved in appearance and performance in the last15 to 20 years. In most cases, if you want a product that was mass-produced fairly recently, you will be satisfied with the price, appearance, and performance.

An exception to this may be passenger cars. Prototype passenger cars were often produced specifically to the designs of each railroad, whereas mass-produced model cars are more generic, except for their paint. They resemble cars for a number of railroads, which makes their production cost effective, but they are not exactly accurate for any railroad. This is problematic for collectors and static modelers, whereas many operators are more interested that the train looks representative rather than exact as it rumbles past. Again, this is another area that depends on the modeler’s priorities.

And, as you would expect, different companies produce products to different price points. The price of the model typically correlates to its accuracy and performance, but this is not always the case, and varies product by product. This is another good reason to join a model railroad club or a Yahoo group for the railroad or product you plan to model. More experienced modelers will know not only how accurate the models from different companies are, but also how well they generally run and how to fix them if there are problems.

Specialty items are usually made as multi-media kits or are brass. These are typically models of products that are not available as mass-production products, such as less popular locomotives and cars, especially those for unique to a particular railroad. Or, they are more accurate models of prototypes than are available from the mass manufacturers. Multi-media kits are generally of structures and railroad cars, especially passenger cars; short production runs of locomotives are usually made of brass for durability and operability.


Brass items, and especially brass locomotives, are worthy of a short discussion themselves. Initially, some brass locomotives and railroad cars were produced in the US, but starting in the mid to late 1950s Japanese producers took that market by producing good quality (for the time) products at much lower prices than US producers. Product quality and accuracy improved with the experience of the brass manufacturers and with the accuracy of the reference material provided to them by their American importers. Generally, the American importer would provide detailed drawings and reference photos to the Japanese manufacturer, who would then produce a production run of the model for that importer. In some cases, an importer would commission a production run of a locomotive from a manufacturer who had already produced this locomotive for another importer. In these situations, the manufacturer would often produce essentially identical models for the second importer.

Later, Japanese products became too costly and production migrated to Korea. Now some brass products are manufactured in China, as are most plastic products.

Generally, newer brass products are more accurate models than older ones. However, most are so pricey that they are aimed more for collectors than operators. In these cases, accurate appearance takes priority over reliable operation; any compromises in appearance needed to achieve smooth, reliable operation are not made.

So, if you just want to run trains, an ever-growing variety of accurate, smooth running plastic steam and Diesel locomotive models is available for your enjoyment. If you want to model a specific railroad, especially specific steam locomotives or rare Diesels, then you need to consider brass. If collecting is your priority, then the newer, more expensive brass models are definitely worth a look. If operating is your priority, then you need to consider mass-produced locomotives and older, less expensive brass models. Older brass may not look quite as stunning as a new brass model, but it may actually run better and be sturdier, with fewer delicate parts to damage during operation. And it will probably be much more affordable. However, brass generally requires some fine-tuning to run well; for smooth operation a good, mass-production locomotive is your best bet unless you need a locomotive type that is only available in brass.

Computer Control? Sound?

Like most other areas of life, the computer revolution has also impacted model trains. Your father’s train set ran on DC (direct current) from a transformer, and many locomotives sold today do the same. However, more and more locomotives are available with computer control. Known as DCC, for Direct Command Control, this is an industry (NMRA ­– National Model Railroad Association) standard that essentially all manufacturers comply with so all the equipment is compatible. In addition to simplifying layout wiring, DCC also enables much more realistic operation.

Furthermore, many locomotives with DCC also have sound. And that makes running trains much more realistic – and fun! The saying in the model railroad community is, if you have 20 locomotives and one has sound, you really have one locomotive. And as a result of all the sound work done for DCC locomotives, more realistic sound is now available for newer DC locomotives. Furthermore, recordings of actual steam and Diesel locomotives in operation are available from various sources, and at least one commercially available sound decoder (from LokSound) allows you to download sounds for use in your model.

So, do you choose DC or DCC? Sound or no sound? If you just plan a seasonal Christmas layout or a static collection, then don’t bother with DCC. DC is cheaper and simpler to set up and learn to operate. However, if you plan anything more than a small or seasonal layout, look seriously at DCC. If you join a model railroad club, see if they are using DC or DCC. Many clubs have either converted to DCC or are planning to do so. DCC is becoming ever more popular and, in my opinion, is the system of choice for serious operators. And if you have DC equipment, it can be converted to DCC with decoders that are available from several manufacturers.

Many current production locomotives are available in two versions, DC and DCC with sound. These are almost always labeled “DCC ready”, which means that you can easily convert them to DCC by installing a DCC decoder into a socket in the locomotive.

Converting a locomotive to sound is a little more challenging due to the need to find a place for the speaker. You want to install the largest speaker that will fit because, in general, the larger the speaker the better the sound quality. If you are converting a locomotive that was also available as a version with sound; there is generally a space with mounting holes already drilled for the speaker that makes this job easier.


You now have the basic information and resources needed to check out model railroading and get started if you are interested. Have fun!


Railroad Books & Videos:

q  Basic Model Railroading: Getting Started in the Hobby by Kent J. Johnson, Kalmbach Publishing Company (November 1998), ISBN-10: 0890243344

q  Guide to North American Steam Locomotives by George H. Drury, Kalmbach Publishing Company (December 1993), ISBN-10: 0890242062

q  The DCC Guide by Don Fiehmann, Kalmbach Publishing Company (October 2007), ISBN-10: 0890246769

q  The Model Railroader's Guide to Passenger Equipment & Operation by Andy Sperandeo, Kalmbach Publishing Company (May 31, 2006), ISBN-10: 0890246203

q  Maintaining and Repairing Your Scale Model Trains by Jim Volhard, Kalmbach Publishing Company (May 1999), ISBN-10: 0890243247

q  The Brass Train Guide Book by Dan Glasure, Brass Guide 2008, ISBN Number: 1882727134 / 9781882727131

Websites and Online:

q  Brass train retailer:

q  Brass trains on consignment and new, mass-produced trains:

q  How do you make your brass steam locomotive run like a charm? See Mark’s brass clinics at:

q  DCC retailer, online DCC and sound tutorials:

q  Java Model Railroad Interface for more advanced users:

q  General model railroad reference:

q  Yahoo groups on prototype railroads and model railroading, such as:

o   Southern Pacific Railroad:

o   Union Pacific Railroad:

o   DCC:

o   Re-powering and re-gearing older locomotives:

o   Passenger cars:

Brass model trains:

Fun Time 6
© Jack Herris, 2008

Steam Locomotive Development in North America

Last time we explored some practical model railroad issues. If you’ve looked at model steam locomotives you probably noticed the many different kinds. But why were there all those different types of locomotives? So let’s look at locomotive evolution on the real railroads.

How Do We Describe Steam Locomotives?

Before we can talk intelligently about the evolution of steam locomotives, we need to discuss how to describe or classify them. While there are different ways to do that, for the common rod locomotives, the most useful, and thus the most common, is called the Whyte system.

The Whyte system is fairly simple. Starting at the front of the locomotive, count the number of non-powered wheels in the front, or pilot, truck if any. Then count the number of driving wheels. Finally, count the number of non-powered wheels, if any, in the trailing truck behind the driving wheels. For example, a locomotive with four wheels in the pilot truck, six driving wheels, and two wheels in a trailing truck behind the drivers, would be described as a 4-6-2. A locomotive with two wheels on its pilot truck, eight drivers, and four wheels in its trailing truck would be described as a 2-8-4.

In addition to the wheel arrangement, other issues arise. The simplest is whether or not the locomotive has a separate tender for fuel and water. If not, there are water tanks and separate fuel tanks or bunkers on the locomotive; this is indicated by a “T” after the wheel arrangement to indicate tank locomotive, meaning no separate tender. An example is a 2-8-2T logging locomotive. Tank locomotives did not have the long range of locomotives with separate tenders, which carried more fuel and water, and were therefore used in short-range operations such as mining, logging, switching, and commuter service.

The above discussion concerns the rod locomotive, the most common design of steam locomotive, in which the driving wheels are moved by rods connected to the steam pistons. However, small, specialized locomotives used gear drive instead of rod drive. These were commonly used for track with sharp curves or steep slopes, such as are found in logging or mining operations. The most common geared locomotive designs are the Shay, Heisler, and Climax, named for their inventors or manufacturers. These are nearly all tank locomotives and are described by their names rather than a Whyte designation since all wheels are driven.

There were many different wheel configurations, and the most popular were even named for convenience when talking about them. But why were there so many? One reason was that railroads ordered steam locomotives custom-built to their specifications, so the variety of steam locomotives was greater than Diesels, which are far more standardized by their manufacturers. But that does not explain all the variations. Steam locomotives were built for different purposes; switching duties, freight hauling, and passenger hauling. Also, locomotive types evolved as operating requirements changed and technology improved.

Switching Steamers

Switch locomotives generally needed to be compact to operate effectively in freight yards. They also needed to have lots of pulling power, called tractive effort. To achieve these conflicting requirements, most had all their weight on their driving wheels, and did not use pilot trucks or trailing trucks. Pilot trucks help locomotives stay on the tracks, but because switch locomotives work at low speeds, they were able to operate safely without pilot trucks. Small switchers had four drivers, medium switchers had six drivers, and large switchers had eight or even ten drivers. These types are written:

0-4-0                0-6-0                0-8-0                0-10-0

The medium 0-6-0 was most common, followed by the 0-8-0. In addition to the locomotives specifically designed for switching duties, older, smaller freight locomotives were also commonly used for switching. This enabled the railroads to avoid buying specially designed switch locomotives and get extra use from their obsolescent small freight locomotives. For example, older 2-8-0 freight locomotives were commonly used for switching, as were, to a lesser extent, 2-6-0 and 2-8-2 locomotives.

Freight Steamers

Steam locomotives designed to haul freight initially had 2-wheel pilot trucks to keep as much weight on the drivers as possible for maximum tractive effort. Due to slow freight speeds, 2-wheel pilot trucks were generally sufficient; 4-wheel pilot trucks were not usually necessary. However, after WWI freight train speeds had to be increased due to competition from trucks, and 4-wheel pilot trucks became more common on freight locomotives for better tracking at those higher speeds. In addition, the 4-10-2 and 4-12-2 type freight locomotives were 3-cylinder designs and needed the larger 4-wheel pilot truck to support the additional weight of a third, center piston and cylinder.

At first, trailing trucks were not needed. However, locomotives became larger and more powerful as the need to haul larger, heavier trains increased. Eventually the firebox on some locomotives became too large to fit in the space between the aft wheels and was often extended behind them. Two-wheel trailing trucks were needed to support the greater weight of the enlarged firebox that often extended behind the driving wheels. In addition, the Santa Fe railroad faced a situation where, in one mountainous location, their 2-10-0 helper locomotives had to back down the mountain for a long distance. To help them move backwards faster without derailing, a 2-wheel trailing truck was added to create a 2-10-2. So while the trailing truck came into use primarily to support larger fireboxes, it also enabled locomotives to run backwards safely at higher speeds.

Initially, the tractive effort of steam locomotives, their pulling power, was the most important criteria because it determined the size of the train they could start and pull. After WWI the need for greater power to move trains faster resulted in a number of innovations, and in particular a new locomotive type with much larger firebox for more power. This larger firebox required a larger, 4-wheel trailing truck for support, and the 2-8-4 type was developed. This was the first of the so-called super-power locomotives, and introduced the final development stage in steam locomotives that was soon followed by the 2-10-4, 4-6-4, 4-8-4, and modern articulateds.

Another path of development led to large articulated locomotives. These locomotives had two sets of drivers supporting a single boiler. To enable these huge locomotives to go around curves, the forward set of drivers was articulated, or allowed to turn with respect to the rear set of drivers, that were built solid with the firebox and frame of the locomotive. A typical articulated locomotive would be designated 2-8-8-2, which means the locomotive had a 2-wheel pilot truck, two sets of eight drivers, and a 2-wheel trailing truck.

Technology also improved as engineers worked to improve safety and efficiency. In addition to tractive effort and power, fuel efficiency was critical and two important technical developments were applied in the 1900–1920 timeframe to improve it. First was the feedwater heater, a device to heat the cold water before it was injected into the boiler. The feedwater heater reduced the fuel needed to heat the cold feedwater by heating the feedwater using waste heat before it was injected into the boiler. This also helped the fireman maintain proper steam pressure and water level in the boiler when adding feedwater. The second device was the superheater, which heated the steam to higher temperature than was needed just to produce the steam. The hotter steam was thermodynamically more efficient and also reduced the problem of steam condensing to water after it contacted the pistons. Not only were the feedwater heater and superheater applied to new locomotives, they were also retrofitted to many existing locomotives to increase their fuel efficiency.

Yet another technique applied to steam locomotives to improve their fuel efficiency was compounding. Compounding means running the steam through the pistons more than once. So-called simple steam engines run the steam through the piston once, then it is exhausted to the air. In contrast, a compound steam engine runs the steam at high pressure to the first piston; the exhaust of that high-pressure piston is then run to a larger low-pressure piston to extract additional work from the same steam. While theoretically more fuel efficient, compounding generally resulted in slow-speed locomotives and required much more maintenance than a simple steam locomotive – a very serious problem given that simple steam locomotives already required considerable maintenance. Although compounding was used on a number of steam locomotives, many, perhaps most, compound steam locomotives were eventually converted to simple steam locomotives without loss of efficiency and with a gain in speed and maintainability. Except for a few experiments, no simple steam locomotives were converted to complex locomotives.

The general evolution of freight steam locomotive types by wheel arrangement is shown below, with the arrows indicating the direction of development. For example, the 2-10-4 was an enlarged 2-8-4 and was not, as one might suppose, developed from the 2-10-2, which was an earlier design. Although the first 2-10-4 was actually a 2-10-2 modified to have a 4-wheel trailing truck, this was a one-of-a-kind prototype that was not developed further. All other 2-10-4 locomotives were developed from the 2-8-4 type, which was a ‘super-power’ locomotive with larger firebox.

2-6-0    Ž  2-6-2


2-8-0    Ž  2-8-2    Ž  2-10-2  Ž  4-10-2  Ž  4-12-2  Ž  4-6-6-4   Ž 4-8-8-4

   ß                ß                                                                (articulated)   (articulated)

2-10-0        2-8-4    Ž 2-10-4 


Articulated Freight Steamers

0-8-8-0   Ž  2-8-8-0   Ž  2-8-8-2   Ž  2-8-8-4


                                          4-8-8-2 (Cab Forward)

Passenger Steamers

Passenger steam locos usually had 4-wheel pilot trucks for better tracking at the higher speeds used by passenger trains. Furthermore, their driving wheels were larger diameter than those of freight locomotives to enable higher speeds to be reached. The general development of steam locomotives designed for passenger service is shown below.

4-4-0    Ž  4-4-2    Ž  4-4-4

   ß                ß

4-6-0    Ž  4-6-2    Ž  4-8-2    Ž  4-8-4



The 4-6-4 was used for high-speed passenger service on routes with shorter trains or that were nearly level. In the West the passenger trains were fewer and longer than in the East, requiring more powerful locomotives to handle larger trains over mountains. The larger, more powerful 4-8-4 became the ultimate passenger steamer and was also powerful enough for use as a fast freight locomotive.

Although early articulated locomotives were usually too slow for passenger service, there were at least two notable exceptions among modern articulated locomotives. The Union Pacific Railroad designed their Challenger type 4-6-6-4 for dual service, and this type was so successful it was purchased by a number of other railroads. And newer versions of the Southern Pacific’s unique Cab Forward articulated locomotives had 4-wheel pilot trucks and were capable of the higher speeds required by passenger trains. The mighty Cab Forwards were used in passenger service over mountain routes.

In addition to the dual-service articulated locomotives noted above, some other locomotives, mostly 4-8-4 types, were designed with both freight and passenger service in mind. Finally, passenger trains were often pulled by steam locos designed for freight service when passenger locomotives were not available.

Southern Pacific’s Unique Cab Forwards

Due to the extensive length of snow tunnels on the Southern Pacific’s difficult route over the Sierra Nevada Mountains (Donner Pass), the SP found that the smoke and fumes from the large 2-8-8-2 articulated locomotives they attempted to use over this route asphyxiated the locomotive’s crew. The unorthodox solution was to run the locomotive in reverse; the crew went through the tunnel before the smokestack and thus were able to breathe. This was possible because the SP had already moved to heavy bunker oil instead of coal to power most of their locomotives. SP then ordered a very successful series of Cab Forward locomotives that eventually totaled 256 engines. There were a number of series and types as described below.

Class AM-2: Ordered for fast passenger service, these 2-6-6-2 locomotives were quickly converted to 4-6-6-2 configuration for better tracking after derailments due to their 2-wheel pilot trucks early in their career. Originally MM-2 compound locomotives, they were converted to simple locomotives and re-designated class AM-2. Used as freight locomotives for most of their lives, they were retired in 1948.

Classes AC-1, -2, and -3: Slow but powerful 2-8-8-2 compound locomotives ordered for freight service, they were originally designated classes MC-4 and MC-6 but were re-designated classes AC-1, -2, and –3 when converted to simple locomotives. Despite their slow speed, these were often used for passenger service over the steep, difficult Donner Pass, where no locomotive was very fast. Three production batches of essentially identical locomotives; the last were retired in 1948. All subsequent AC classes were designed and built as simple locomotives for higher speed and reduced maintenance.

Classes AC-4, -5, and -6: Powerful, fairly fast 4-8-8-2 locomotives ordered for fast freight service, they were distinctly more modern than the earlier AC classes in all respects. The AC-6 batch differed in steam pressure and minor details from the AC-4 and AC-5 batches. Much faster than earlier Cab Forwards and used in passenger service in the mountains, all lasted until the end of steam.

Classes AC-7, -8, 10, 11, and -12: Powerful, fairly fast 4-8-8-2 locomotives ordered for fast freight service and also used in passenger service in the mountains. These were five batches of essentially identical locomotives that lasted until the end of steam. The very last built, AC-12 #4294, rests in the California Railroad Museum in Sacramento; it is the only surviving Cab Forward.

Class AC-9: Conventional (cab aft) 2-8-8-4 locomotives ordered for fast freight service. These were coal-burning locomotives intended for use in the desert where there were no snow tunnels, so the cab forward configuration was not needed. Designed to the same technical specifications as the late Cab Forwards, they were converted to oil burners in the early 1950s and lasted until 1955.

American Steam Locomotive Wheel Arrangements

Here is a summary of the most common American steam locomotive types. With few exceptions, such as the 2-8-8-2, common wheel arrangements were named.

Whyte        Common Name        Notes

0-4-0           Four-coupled             Switch engine

0-4-4T         Forney four-coupled  Industrial use

0-6-0           Six-coupled               Switcher

0-6-4T         Forney six-coupled    Industrial use

0-6-6-0        none                           First articulated Mallet in USA

0-8-0           Eight-coupled            Switcher

0-8-8-0        Angus                        Low speed helper locomotive

0-10-0         Ten-coupled               Heavy switcher

0-10-2         Union                         Heavy switcher; 5 built for Union RR, Pittsburg

2-4-4-2        none                           Smallest articulated, used for logging

2-6-0           Mogul                        Freight

2-6-2           Prairie                        Dual use

2-6-4T         none                           Suburban passenger service

2-6-6-2        none                           Freight

2-6-6-4        none                           Freight

2-6-6-6        Allegheny                  Freight

2-6-8-0        none                           Freight, used by GN and Southern

2-8-0           Consolidation            Freight

2-8-2           Mikado                      Freight

2-8-4           Berkshire                   Freight, first super-power locomotive

2-8-8-0        Bull Moose                Freight

2-8-8-2        none                           Freight

2-8-8-4        Yellowstone              Freight

2-8-8-8-2     Triplex                       Freight (one 2-8-8-8-4 was built)

2-10-0         Decapod                    Freight

2-10-2         Santa Fe                     Freight, Santa Fe RR was first user

2-10-4         Texas                         Freight, Texas & Pacific RR was first user

2-10-10-2    none                           Freight, used by Santa Fe and Virginian railroads

4-2-2           Bicycle                       Dual purpose

4-4-0           American                   Dual purpose, widely used early type

4-4-2           Atlantic                      Passenger

4-4-4           Jubilee                        Passenger

4-6-0           Ten-wheeler               Passenger

4-6-2           Pacific                        Passenger

4-4-4-4        Duplex                       Passenger

4-4-6-2        none                           Passenger

4-4-6-4        Duplex                       Freight

4-6-6-2        Cab Forward             Passenger

4-6-6-4        Challenger                 Dual purpose

4-8-0           Twelve-wheeler         Freight, also called Mastodon

4-8-2           Mountain                   Passenger, NYC called theirs Mohawk

4-8-4           Northern                    Passenger, Northern Pacific was first to use,

                                                      some railroads used other names

4-8-8-2        Cab Forward             Dual purpose

4-8-8-4        Big Boy                     Freight

4-10-0         Mastodon                  Freight, one built for Central Pacific

4-10-2         Southern Pacific        Freight, Southern Pacific was first to use

4-12-2         Union Pacific             Freight, Union Pacific was first to use

6-4-4-6        The Big Engine          Passenger, one built for PRR

6-8-6           none                           Dual purpose, one built for PRR


You now have a basic overview of steam locomotive development, with a special look at the Southern Pacific’s unique Cab Forwards. For further information, check the books and other resources below.


Railroad Books & Videos:

q  If you want more information on steam locomotives, this is probably the first book to read: Guide to North American Steam Locomotives by George H. Drury, Kalmbach Publishing Company (December 1993), ISBN-10: 0890242062

q  American Steam Locomotive by Brian Solomon, MBI (May 23, 1998), ISBN-10: 0760303363

q  Cab-Forward: The Story of Southern Pacific Articulated Locomotives by Robert J. Church, Central Valley Railroad Publications; Revised Edition edition (1982), ASIN: B0006EDVP6

q  Perfecting the American Steam Locomotive by J. Parker Lamb, Indiana University Press (June 2003), ISBN-10: 0253342198

q  Model Railroader Cyclopedia: Steam Locomotives by Linn Westcott, Kalmbach Publishing Company (June 1980), ISBN-10: 0890240019

Websites and Online:

q  Steam locomotive site:

q  Extreme steam locomotives; unusual variations on the steam locomotive:

q  Yahoo groups on prototype railroads and model railroading, such as:

o   Southern Pacific Railroad:

Union Pacific Railroad:

Fun Time 7
© Jack Herris, 2008

Turbine and Diesel Locomotive Development in North America

Last time we explored steam locomotive evolution on North American railroads, so it is only natural to follow that with a discussion of the locomotives that replaced steam, the turbine and Diesel locomotives.

Why Diesel Locomotives?

As you may have noticed, I love steam locomotives. They are huge, powerful, impressive, have their own distinct personality, and they changed the world by making railroads practical. However, they have a number of drawbacks, and if I owned a railroad, that railroad would use Diesel locomotives despite my love of steamers. Why is that?

The most important reason Diesels replaced steam locomotives is economic. First, Diesels need far less maintenance than steam locomotives, which translates into much lower costs due to a far smaller maintenance workforce and smaller facilities. The difference in maintenance costs between steam and Diesel is huge and therefore compelling. Whereas steam locomotives changed the world, Diesel locomotives changed the economics of railroading. In addition to lower maintenance costs, Diesels also do about twice the amount of work as steamers with the same amount of fuel. The difference in fuel cost is very important, especially with today’s oil prices. Of course, steam locomotives could also coal and wood for fuel, something Diesels cannot do.

Another Diesel advantage is that they are easier on the track, reducing track maintenance requirements. There are two reasons for this. First, the unbalanced dynamic forces of the driving mechanism on steam locomotives pounded the track, loosening the spikes and ties. Second, the driving wheels of steam locomotives have a longer wheelbase than Diesels, so when steamers go around curves they try to spread the track apart much more than Diesels do, creating more track wear and more maintenance to do.

Diesels also have some operational advantages over steam locomotives. Diesels are easier and faster to start and get into operation, they don’t need to stop for water or other consumables nearly as often as steamers, and they can have dynamic brakes. As mentioned in an earlier column, dynamic brakes are the ability of the Diesel, when going down grades, to get braking from the Diesel engine. This greatly simplifies and speeds operations in areas with grades.

Finally, and increasingly important, Diesels are cleaner than steamers. Steam locomotives were noted for their heavy smoke pollution, which made them unpopular in cities even before the environment was nearly as big a concern as it is today. Although not pollution-free, Diesels essentially solved this problem.

The Competitive Environment

Diesel engines for locomotives got their start in the 1920s when railroad management was looking for cheap passenger transportation for routes with low ridership. These routes had too few paying passengers to make steam-powered passenger trains economic, and management looked for cheaper ways of addressing this need. Internal combustion engines, first gasoline, later Diesel, were tried in self-propelled passenger cars, and their operational success led to designs for Diesel powered switch engines.

Early Diesel locomotives had neither the power nor sturdiness to replace steam in mainline freight service, but from the 1930s they gradually proved their reliability in switching duties. As locomotive manufacturers and railroads became more experienced with Diesels, more powerful Diesels were developed that were successfully applied to streamlined passenger trains in the late 1930s. By 1940 the Diesel (in the form of the FT series from the Electro-Motive Division of General Motors, formerly the Electro-Motive Corporation) had finally proved itself in mainline freight service, and the writing was on the wall for the future of steam.

However, replacing steam locomotives, especially in heavy freight service, was not easy. By the late 1920s modern steam locomotives were developing more than 6,000 hp. The most powerful steamers ever measured were the 2-6-6-6 Alleghany at 7,500 hp and the Pennsylvania Railroad’s 4-4-6-4 Q-2 at 8,000 hp; both were production steamers delivered in the 1940s. The Pennsylvania Railroad’s huge 6-4-4-6 S-1 passenger locomotive, exhibited at the 1939/1940 World’s Fair in New York, was measured at 7,200 hp and could easily pull a 1,200 ton passenger train at 100 mph. The impressive performance of modern steam locomotives raised the bar for competing Diesels and led many at the time to question whether Diesels would ever demonstrate the toughness and performance to replace steam, especially in heavy freight service.

In stark contrast, early Diesel locomotives were typically rated at 1,500 hp, far less than large steamers. So passenger and freight Diesels were designed from the outset to operate in sets of three, four, or more to deliver the needed power. In essence the Diesel was a modular locomotive; the railroads just hooked together as many as necessary. And they were connected so one engineer controlled the entire set. In contrast, steam locomotives required a separate crew for each locomotive. The most powerful Diesel locomotive ever to see service, the Union Pacific’s Centennial series, incorporated two Diesel prime movers (engines) into one chassis and had a total of 6,600 hp. Today’s most powerful Diesels develop 6,000 hp with a single engine. Yet even today’s Diesels are not as powerful as the steamers of the late 1920s!

The Impact of External Events

The most important external event affecting the steam to Diesel transition in America was World War II. Preparation for the war and the war itself generated ever increasing amounts of railroad traffic just as the Diesel was proving itself in mainline freight service. Some railroads were early adapters of Diesel power and had ordered or already received substantial numbers of freight Diesels by 1941. But Pearl Harbor and America’s entry into the war as a direct combatant changed everything. First, traffic immediately soared to new highs, resulting in an extreme demand for motive power. Second, the War Production Board assumed control of locomotive production. With high demand for large Diesel engines from the Navy for submarines and landing craft, very few Diesel locomotives were built for the railroads. The result was a number of railroads that ordered Diesel locomotives during the war, or wanted to do so, were forced to settle for steam locomotives.

With the end of the war, the railroads were exhausted and their locomotives, rolling stock, and track were all suffering from deferred maintenance due to higher wartime priorities for the resources. Many steam locomotives were simply worn out, and many others, having been recalled from retirement when the war started, were obsolete. All these locomotives needed to be replaced, and almost without exception they were replaced with Diesels.

Diesel Evolution

As already noted, the first Diesel locomotives were relatively small, low-powered models for switching duties. These were not intended for use at high speed so were boxy, non-streamlined locomotives with cabs featuring large windows for good all-around visibility in the freight yard environment. Power for these locomotives was typically 900–1200 hp.

The next Diesel locomotives were larger, more powerful models designed to haul streamlined passenger trains. For esthetic and marketing reasons they were streamlined and painted to match the passenger cars. Initially, the same locomotive types, suitably geared down for more pulling power and lower speed, were also used for freight trains. These locomotives were generally of 1,500–1,750 hp, with some as high as 2,250 hp.

The next step in Diesel locomotive fashion was the road-switcher, a type that combined the boxy look and high visibility cab windows of switch engines with the larger size and greater power of passenger and freight Diesels. These locomotives were marketed to the railroads as versatile, dual-purpose locomotives equally suitable for road freight hauling and switching duties. By the end of the 1950s, the greater visibility from the road switcher compared to streamlined Diesels proved decisive, and all new locomotives were essentially designed to be road switchers; streamlined Diesels were no longer being produced.

By the late 1950s Dieselization was complete on major North American railroads, and railroad managements were looking for more powerful Diesels to reduce the number of units they had to purchase and maintain. Developing more powerful prime-movers (as the engine itself is called) was difficult and expensive for the locomotive manufacturers, and they had little incentive to do so and thereby reduce demand for the number of locomotives required. Railroad management was forced to pursue different alternatives.

Union Pacific Railroad decided to turbo-charge some of their Diesels to get more power. Their efforts, with reluctant support from the manufacturer, were successful and the manufacturer started offering new, more powerful turbo-charged locomotives.

After studies indicating that Diesel maintenance costs were essentially independent of the unit’s size and power, Union Pacific also specifically requested locomotives from the manufacturers with two engines to create more powerful units. The resulting dual-Diesel locomotives were used for some time by the Union Pacific, but with one exception remained unique to it. Only the Southern Pacific purchased a handful of these dual-engine units for evaluation and did not follow up with more orders.

The Southern Pacific, faced with problems similar to those experienced by the Union Pacific, finally went to foreign manufacturers for more powerful Diesels. The SP imported some German units with 4,000 hp engines at the time when 2,400 hp was about the best American manufacturers offered. This was intended not only to get more powerful locomotives for the SP, but also to put pressure on American manufacturers to offer more powerful locomotives.

In addition to their greater power, these German units had another innovation. Most Diesel locomotives use Diesel-electric drive. This means the Diesel engine powers an electrical generator, and the current from that generator is used to power traction motors on each driving axle of the locomotive. The problem was that traction motors of the time were limited to 500 hp, limiting the power per axle. The German locomotives were hydraulic drive; their Diesel engine drove a hydraulic pump that powered hydraulic motors in the trucks. This eliminated the power per axle limitation of the traction motors. While successful in Europe, hydraulic drive was less successful in American operating conditions. There were several reasons for this, including that American railroaders were used to traction motors and the hydraulic drive Diesels were therefore viewed as an odd, foreign innovation at a time, the early 1960s, when things American were definitely preferred to things foreign on the railroads.

The net result of the pressure from the railroads – especially UP and SP – for more powerful Diesel locomotives was that American locomotive manufacturers decided they had better develop more powerful locomotives or risk losing their market. Soon more powerful locomotives using a single, more powerful prime-mover and more powerful traction motors were being offered by the manufacturers and eagerly purchased by the railroads.

Steam Turbine Tangent

Although Diesel locomotives have dominated the discussion to this point, Diesels were not the only new type of power investigated to replace conventional steamers. Two different types of turbine engine, the steam turbine and the gas turbine, were also tried.

By the late 1930s steam turbines had been in use in ships and stationary power plants for many years. This successful experience, coupled with the familiarity of steam, lead to steam turbines being tried in locomotives. The first steam turbine locomotive was made by General Electric Company for the Union Pacific in 1938 for hauling a streamlined passenger train. The two units built worked, but, like all new technology, had teething troubles. After six months of testing the units were withdrawn from service.

The Pennsylvania Railroad, the Chesapeake & Ohio, and the Norfolk & Western railroads all tried their own versions of steam turbine locomotives. Pennsy received one coal-burning steam turbine locomotive in 1944. Using a gear drive from the turbine, it was a fast, powerful, 6,900 hp locomotive that could out-pull anything on rails at the time and was used in passenger service. Unfortunately, at low speeds it used enormous amounts of coal and water, and eventually it was scrapped in favor of Diesel locomotives.

The C&O built three coal-burning steam turbines in 1947 and 1948 using turbine-electric drive. These huge units were simply too complex and unreliable; by the middle of 1948 the C&O decided to Dieselize. The final steam turbine locomotive was delivered to the N&W in 1954. Like the C&O steam turbines, it was coal-burning and used turbine-electric drive. It was smaller and less complex than the C&O turbines and much more successful, but still was scrapped in 1958 in favor of Diesels.

Locomotives are much less benign operating environments than ships and power plants. They vibrate more, are subject to much more mechanical shock, and constantly change speeds. Furthermore, the need for a compact design to fit on the rails makes it more difficult to keep coal dust out of the rest of the mechanism, especially the traction motors and other electrical components. While these problems are solvable with time and effort, the Diesel was, by this time, a readily-available, proven solution. Railroad management had many other demands for their attention and investment, and Diesels were the easy choice.

Gas Turbines – the Big Blow

While the steam turbine locomotive was quickly discarded in favor of the Diesel, the gas turbine locomotive was more successful.

In America the gas turbine locomotive was a joint development of GE and the Union Pacific, last seen together in 1938 trying a steam turbine without great success. However, during World War II GE was given a prototype jet airplane engine developed in Britain and was asked to manufacture it in America for warplanes. GE went on to become a major jet engine manufacturer. Post war, GE wanted to expand their jet engine market and UP wanted more powerful locomotives than the 1,500 hp Diesels then on offer. The result was a gas turbine locomotive of 4,500 hp. The prototype was demonstrated to several railroads but only UP ordered production models in three distinct production batches and variations. Delivery of the 4,500 hp production model started in 1952; the final version, initially rated at 8,500 hp and later up-rated to 10,000 hp, was delivered from 1958 and remains the most powerful locomotive in history. Like Diesels, these gas-turbine locomotives used generators and traction motors to power their wheels.

The gas turbine locomotives had much more power than competing Diesels, which was a key advantage for the Union Pacific. Used for hauling heavy freight trains over long distances, the turbines were initially very useful to UP. The turbines used heavy oil that was relatively cheap at first, but later became more expensive as more uses were found for it. The turbines were reasonably efficient at full power, where they were intended to operate, but guzzled fuel at rest and low power. In addition, like any jet engine they were noisy, a characteristic that gave the final model their nickname of the “Big Blow”. While the noise could be tolerated on much of UP’s route system over the Great Plains, it was not acceptable in heavily-populated areas.

Union Pacific’s turbine story would not be complete without mention of their prototype coal turbine. Unlike earlier coal-burning turbines, which burned the coal to produce steam that then powered the turbine, this prototype burned powdered coal in the turbine itself. In contrast, conventional gas turbines burned liquid fuel in the turbine. This locomotive was built in 1962 by the UP in conjunction with GE and Alco (American Locomotive Company) and tested in revenue service for some time. Along with coal particles causing problems with the electrical components, as experienced earlier by the C&O and N&W prototypes, the powdered coal eroded the turbine blades too quickly and the experiment was eventually dropped.

Although a few specifically-designed turbine-powered passenger train sets were active into the 1980s, high fuel consumption and noise spelled the end of the gas turbine locomotive in general service.


You now have a basic overview of Diesel and turbine locomotive development. While turbines offer some advantages, continued development of the Diesel provided a practical and economic solution to the railroads without the time, effort, and resources required to bring the turbine to a comparable state of practical development. For now, the Diesel locomotive reigns supreme. However, as petroleum becomes more expensive and harder to find, might the coal turbine and coal-steam turbine be investigated again?

For further information, check the books and other resources below.


Railroad Books & Videos:

q  For much more information on development of both steam and Diesel locomotives on one of America’s most famous railroads, read: Santa Fe Locomotive Development by Larry E. Brasher, Signature Press (2006), ISBN: 978-1-930013-20-9

q  For information on Union Pacific’s turbine locomotives and dual-Diesel locomotives, read: Giants of the West: A Pictorial Presentation of Union Pacific’s Super Powered Locos by George R. Cockle, Overland Publications (1981), ISBN-10: 0-916160-12-2

q  For more information on Union Pacific’s turbine locomotives, read: Union Pacific's Turbine Era by A. J. Wolff, Withers Publishing (2001), ISBN-10: 1-881411-30-3

q  Another useful book on Union Pacific’s turbine locomotives is: Turbines Westward by Thos. R. Lee, T. Lee Publications (1975), ISBN-10: 0-9162-44-01-6

q  Model Railroader Cyclopedia: Diesel Locomotives by Bob Hayden, Kalmbach Publishing Company (June 1980), ISBN-10: 0890245479

Websites and Online:

q  EMD Diesel locomotive site:

q  GE Diesel locomotive site:

q  List of ALCO diesel locomotives:

q  Gas turbine-electric locomotive site:

q  Steam turbine locomotive site:

q  Yahoo groups on prototype railroads and model railroading.