How Powerful Is A Steam Locomotive?

Steam locomotives were once a crucial part of the global economy, given that they were used for transporting people, goods, and raw materials to the better part of the world. They might not be as fast or strong as the modern trains, but they had their purpose in propelling global trade and connecting cities. Steam locomotives are still very strong and can haul heavy loads, prompting many train lovers to ask exactly how powerful these trains are.

A steam locomotive has an average tractive effort (pull or push force) of 37,000 pounds, mostly found in a K37 engine. However, the K27 had a tractive effort of 27,000 pounds. The Union Pacific ‘Big Boy’ 4014 is the most powerful steam locomotive with a tractive effort of 135,375 pounds.

That’s not all, as you still need to know the amount of torque a steam locomotive can have, whether steam locomotives are still in use and built and whether this type of engine is more powerful than a diesel one, which you will learn if you read on.

logging railroad
Jeff Hampton

What’s the Power of a Steam Locomotive?

Steam locomotives were a backbone of global industrial growth as they helped to usher in the much-needed economic growth. They were preferred since they could accommodate and haul heavy loads and travel greater distances.

Besides what they could carry, the steam locomotives were an ideal choice for many factories and companies due to their immense power. They were built for power, given the amount of work required and the unfavorable landscapes back then. Just how powerful were the steam locomotives?

Steam locomotives came in different sizes, designs, and power capabilities as they were meant for different purposes. Not all steam engines were used on locomotives, and the ones that did had a minimum tractive effort required. Here are the common ones:

  • The K27 Engine –had a tractive effort of 27,000 pounds and was found in the earlier models of locomotives.
  • The K37 –had a tractive effort of 37,000 pounds and was considered a significant upgrade to the K27.

These engines might have been powerful but are no longer in service. However, there’s still one very powerful steam locomotive in operation in the United States, and it’s the ‘Big Boy’ from Union Pacific, with a tractive effort of 135,375 pounds.

The tractive effort is the ability of the train to push or pull a load. It’s measured in pounds as it’s the amount of weight a steam locomotive can pull on one trip. Exceeding this capability would overload the engine and damage it.

How Much Torque does a Steam Locomotive Have?

Although there’s no way of knowing the exact figures to determine the amount of torque in a steam locomotive, it’s safe to say that such an engine produces more torque as it runs. It’s also capable of producing maximum torque at 0 RPM, which is more than a diesel engine.

The amount of torque produced by a steam locomotive depends on steam pressure, driver diameter, and cylinder bore and stroke. If a locomotive has a massive steam pressure, you should expect the torque also to be higher. Similarly, it’s usually hard to start a locomotive with a huge driver diameter, and this would require a lot of torque to get it moving.

The cylinder bore is used to ingest fuel into a combustion chamber, and the wider the cylinder, the more fuel can flow through it. With huge amounts of fuel directed into the combustion chamber, you should expect more energy and torque.

Locomotives with these components in mid-sizes or smaller measurements would struggle to produce the amount of torque needed.

rio grande
Bill Hooper

How Many Cars can a Steam Locomotive Pull?

On average, a steam locomotive can pull around 23 fully-loaded cars. However, the number of cars depends on the terrain, the load, and the engine size. The sharpness of the track’s curve and its grade is another issue to consider.

Even so, there have been cases where a steam locomotive pulled many carts at a go, with a great example being the Challenger 3985 that hauled 147 cars while still maintaining speeds of 65 MPH.

The total tractive effort of a steam locomotive determines the number of carts it can pull. However, since the locomotive’s torque increases as the train run, it’s hard to see how such an engine cannot pull more carts. The landscape of the route also determines the number of carts one steam locomotive can handle. For instance, it’s hard for a steam train to pull many carts on hilly terrain than on a flat surface.

Additionally, the weight of the carts also determines the number you can attach to one steam train without overloading the engine.

What is the Largest Steam Engine ever Built?

Steam locomotives are known for their sheer size, which was a standard requirement given the heavy work they were supposed to carry out. Currently, the largest steam engine in existence is the Union Pacific Railroad ‘Big Boy’ 4014. It has a 4-8-8-4 wheel arrangement and was meant to haul heavy objects without requiring assistance from helper locomotives.

Additionally, the locomotive weighs an astonishing 600 tons, has a horsepower of 6,290, and measures 132 feet. It drives at 70 MPH top speed, with a steam pressure of 300 PSI. It’s fueled by coal and can run for 100 miles without needing servicing.

The locomotive is still in use, and you can see it in Wyoming, although it keeps moving. The locomotive has attracted a lot of attention after it was revived in 2014, and many have even considered it one of the greatest steam locomotives ever made.

locomotive weight
Bill Johnson

Are Steam Locomotives Still in Use?

Although diesel-powered and electric trains are taking over the world, there are still some parts of the world where the steam locomotive is very active. For instance, this type of transportation is widely used to connect the rural areas of India.

Currently, the country has over 250 steam locomotives still in service, with a huge chunk of the fleet retired and placed in museums. The decline in their use is a consequence of embracing new technology and adopting diesel engines that are considered easier to manage, have a longer lifespan, and can haul heavier loads.

China is another place you can find steam locomotives, especially in the Western region. However, their use is dwindling, given the country’s massive investment in high-speed trains. Currently, there’s only one steam train serving passengers, Jiayang Steam Train, and there’re plans to retire it.

South America is still big on steam locomotives, especially in Venezuela. Parts of Eastern Europe still use the steam train to carry people and cargo across the countries. Although the steam trains are disappearing as the diesel and electric trains take over, some governments are still reconsidering reintroducing them, but only as part of culture and heritage. Most of the trains would be used for recreational purposes and to educate the new generation about where the innovation started.

Why did Steam Locomotive’s Use Decline?

Steam locomotives might have been useful a few decades ago, but they have become absolute in recent years. Their replacement was systematic, and they’re now viewed as ancient technology passed by time. What exactly led to their decline when they seemed irreplaceable?

powerful steam locomotive
Jeff Hampton

Technological Advancements

Technology is evolving, and we’re at a golden age where everything is dependent on new innovations. Steam locomotives were the first culprits of these changes as they were deemed ineffective. New ways of traveling were discovered that were cheaper than steam.

Type of Fuel

Steam locomotives relied on coal as a primary source of fuel. Coal might be cheaper than diesel, but you need it in bulk to power one steam train. This meant having more space to store the coal, which added to the overall weight of the train. There was also the issue of pollution, as you won’t have hundreds of these trains in a city and not face the fog problem.


Every transportation method requires being efficient enough to serve its purpose. For the longest time, steam locomotives might have been efficient given the alternative. However, that efficiency was only 10%, with 90% of the energy going to waste. The diesel trains promised 40% efficiency, which was an upgrade. Even so, none of them compare to the 90% efficiency offered by electric trains.

Maintenance Costs

It was considered economically unsound to maintain a steam locomotive, given the costs associated with running the train. For instance, you needed many people to operate and service the train, which added to the labor cost. The resources were also needed in bulk, which was eating into a huge chunk of profits.


Steam locomotives were once a pride and joy for many. However, with all developments and advancements taking place globally, it was hard to continue using outdated means of transportation. A need for comfort, speed, and class contributed to the development of diesel, electric, and high-speed trains, rendering the steam ones absolute.

Santa Fe steam locomotive
Drew Jacksich Photo

Are Steam Locomotives Still Being Built?

Unfortunately, the production of steam locomotives was halted a few years ago, paving the way for new and improved trains. The cost of building and maintaining one was too much for governments and businesses to handle. People’s attention was also focusing on newer and more advanced trains and didn’t see a need to bother with the old.

The steam locomotives that are still operational today date back almost a hundred years. There are also environmental concerns, given that the world is moving toward a cleaner and renewable energy. Coal might have been cheaper, but the waste was too costly to the environment. It wasn’t seen as a viable long-term energy supply, and electricity performed much better.

Instead of building new ones, governments and railway companies are opting to revive the older models by equipping them with better-performing engine parts. They’ve also improved on the comfort, making the renewed steam locomotives worth a ride.

Many of these revived locomotives are barely used to ferry people or cargo but as a cultural attraction where people pay to see them. Most of them are nearly a century old and are connected to the industrial revolution that paved the way for current developments.

Are Steam Locomotives More Powerful than Diesel?

A lot of things determine how powerful an engine is by looking at the following:

  • Horsepower
  • The engine’s size
  • Tractive effort


The amount of horsepower determines an engine’s strength. Huge models of steam locomotives are very powerful and can give off over 4,000 HP. They’re also large in size and require a lot of fuel to run them. The more fuel an engine requires, the more power it gives off.

However, a diesel engine has several edges over the steam one, and they include:

  • Starting power – a diesel engine can start and take off very fast, given that it can utilize its full power almost immediately. The steam engine requires a bit of time to accelerate and gain enough power.
  • Combining factor – you can combine two diesel engines, adding more power. It’s usually common in bigger freight trains. You can only use one steam engine at a go.

Sophisticated steam locomotives like the ‘Big Boy’ are three times powerful as modern diesel engines. A steam locomotive also becomes more powerful as it gains speed and produces constant pulling effort, making it more powerful at top speed.

Bigger diesel locomotives are more powerful than smaller steam ones as they have more horsepower and can handle more fuel.


Steam locomotives were once an industrial jewel. They performed better in hauling goods and transporting masses of people than the alternative modes of transport at that time. Their power is measured in horsepower, with bigger ones being very powerful than the small ones. Some countries are still using them, although many favor diesel and electric trains. They’re not being built anymore as the focus has shifted to more efficient diesel and electric ones. A steam locomotive can haul around 23 fully loaded cars, although there’re those that can pull more. The ‘Big Boy’ steam locomotive is the biggest of its kind in existence today.


Lifelong Rail Enthusiast and Owner of Worldwide Rails

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