UIC classification of locomotive axle arrangements facts for kids

Trains are amazing machines! Have you ever wondered how people describe the different types of trains, especially how their wheels are arranged? The International Union of Railways (UIC) has a special way to classify, or sort, locomotives, multiple units, and trams based on their wheel arrangements. This system is called the UIC classification of locomotive axle arrangements. It's used in many parts of the world to easily understand how a train's wheels are powered and organized.

How Train Wheels Are Classified

Every train, from a powerful locomotive to a speedy tram, has wheels. The way these wheels are arranged, and which ones are powered, tells us a lot about the train. The UIC system is like a secret code that helps engineers and train enthusiasts quickly understand a train's design.

What Does the UIC System Describe?

The UIC system focuses on the axles of a train. An axle is a rod that connects two wheels. Think of it like the bar between the wheels of a skateboard.

• Powered axles: These are axles that have their own traction motor to make the wheels turn. This is how the train moves!
• Unpowered axles: These axles just roll along and don't have a motor directly powering them. They help support the train's weight.
• Bogies: A bogie is like a mini-frame with its own set of wheels and axles. Many modern trains have two or more bogies under them. Each bogie can turn separately from the main body of the train, which helps the train go around curves more easily.

The UIC system uses letters and symbols to show how many axles are on each bogie and whether they are powered.

Common UIC Examples

Let's look at some common examples of how trains are classified using the UIC system. These codes might look tricky at first, but they are quite simple once you know what each part means!

Bo'Bo'

• Meaning: This is a very common arrangement for many locomotives.
• Breakdown:
  • The first Bo means there's a bogie with two powered axles. Each axle has its own motor.
  • The apostrophe () means that each axle on that bogie is driven by its own separate motor.
  • The second Bo means there's another bogie, also with two powered axles, each with its own motor.
• In simple terms: Imagine a train with two separate wheel sets (bogies) underneath it. Each of these sets has two wheels that are powered by their own motors. This makes the train strong and flexible.

Co'Co'

• Meaning: This arrangement is often found on heavier or more powerful locomotives.
• Breakdown:
  • The first Co means there's a bogie with three powered axles. Each axle has its own motor.
  • The apostrophe () again means each axle on that bogie is driven by its own separate motor.
  • The second Co means there's another bogie, also with three powered axles, each with its own motor.
• In simple terms: This train has two bogies, and each bogie has three wheels that are powered individually. More powered wheels mean more pulling power!

Co'Bo'

• Meaning: This is a less common but interesting mix.
• Breakdown:
  • The first Co means one bogie has three powered axles, each with its own motor.
  • The apostrophe () shows individual axle drive.
  • The second Bo means the other bogie has two powered axles, each with its own motor.
• In simple terms: This train has two bogies, but they are different! One bogie has three powered wheels, and the other has two powered wheels. All these wheels are powered individually.

Other Classification Systems

While the UIC system is used in many parts of the world, other countries have their own ways of classifying train wheels.

• The United Kingdom used a similar system, but with slightly different names (like Bo-Bo instead of Bo'Bo').
• The United States uses a simpler system called the AAR wheel arrangement for modern locomotives.

See also

In Spanish: Clasificación UIC de disposiciones de ejes de locomotoras para niños