What is the primary function of the main reservoirs on a locomotive?

The primary function of the main reservoirs on a locomotive is to store, cool, and dry the supply of compressed air. These reservoirs play a critical role in the locomotive's air brake system by ensuring that there is a sufficient supply of compressed air available for braking and other pneumatic systems.

When air is compressed, it can contain moisture and impurities, which can be detrimental to the proper functioning of the air brakes. Therefore, the reservoirs help cool the air and allow any moisture to condense, ensuring that the air is dry and free of contaminants before it is used in critical applications. This process is vital for maintaining the reliability and safety of the braking system, as any issues with moisture or impurities could lead to brake malfunction.

In summary, the main reservoirs are essential for storing and conditioning compressed air to ensure that the air brake system operates efficiently and safely.