Understanding the Configuration of Diesel Locomotive Drivetrains and Powered Wheels

The efficient operation of a diesel locomotive relies heavily on its drivetrain configuration. This system is designed to convert the mechanical energy from a diesel engine into the motion of the locomotive's wheels. Whether using a diesel-electric, diesel-mechanical, or diesel-hydraulic configuration, the objective remains the same: to move the locomotive along the tracks. Let's delve into the details of how these systems work and the specific configurations of powered wheels in diesel locomotives.

Diesel-Electric Locomotive Drivetrain

Diesel-electric locomotives are the most common type used in modern railway systems. In this setup, the diesel engine is the main power source, but it doesn’t drive the wheels directly. Instead, the diesel engine powers a generator or alternator, converting its mechanical energy into electrical energy. This electrical energy is then sent to traction motors, which convert the electrical energy back into mechanical energy to turn the powered wheels.

Key Components of a Diesel-Electric Drivetrain

Diesel Engine: Powers the generator or alternator. Generator/Alternator: Converts mechanical energy from the engine into electrical energy. Traction Motors: Turn the electrical energy back into mechanical energy to drive the locomotive's wheels.

Axle Configurations

The traction motors in a diesel-electric locomotive typically drive specific axles, which can vary depending on the design of the locomotive. Here are some common configurations:

B-B: Four powered wheels, with two bogies and two powered axles each. A1A-A1A: Six wheels with three powered axles and three non-powered axles. C-C: Six powered wheels, with two bogies and three powered axles each.

In the configuration WDM2, which stands for Wide or BroadGauge, Diesel Engine Driven, and Mixed Service, each bogie has three axles, and each axle is driven by one traction motor. This setup is commonly used due to its efficiency and reliability.

Diesel-Mechanical and Diesel-Hydraulic Locomotive Drivetrains

These two configurations provide a direct power transfer from the diesel engine to the wheels, eliminating the need for a generator or traction motor. In a diesel-mechanical system, the engine drives the wheels through a mechanical transmission, while in a diesel-hydraulic system, the engine drives a hydraulic system that then transfers power to the wheels.

Powered Wheels

In diesel-mechanical and diesel-hydraulic systems, the configuration of powered wheels can vary widely. Some locomotives, like those with B-B configuration, have all wheels powered, while others, like those with A1A-A1A, have specific axles powered. The choice of configuration depends on the design and intended use of the locomotive.

Summary

In most diesel-electric locomotives, the traction motors drive specific axles, which are typically located on the rear bogie but can vary depending on the design. In mechanical or hydraulic systems, the diesel engine drives the wheels directly, often resulting in all wheels being powered or specific axles depending on the design. The specific configuration of powered wheels can vary based on the design and intended use of the locomotive.

Note: The term WDM2 stands for Wide or BroadGauge, Diesel Engine Driven, and Mixed Service, which can be used to describe a locomotive with specific characteristics, such as having two bogies, three axles per bogie, and each axle driven by one traction motor.