8406.90.45.40 - Rotors or spindles and rotor or spindle assemblies

This HTS category, 8406.90.45.40, specifically covers rotors or spindles, as well as complete rotor or spindle assemblies, that are components of steam turbines and other vapor turbines. These are critical rotating parts that form the core of the turbine's energy conversion mechanism, where steam or vapor causes rotation to generate mechanical power. This classification applies to the actual rotating shafts and their associated rotating elements, designed for use within the steam turbine.

Distinguishing this category from its sibling, 8406.90.45.80 ("Other"), is crucial for accurate classification. While 8406.90.45.80 encompasses a broader range of parts for steam turbines that do not fit the specific definition of rotors or spindles, 8406.90.45.40 is narrowly focused on these precise rotating components and their assemblies. For example, a turbine casing or a blade separate from the rotor would likely fall under the "Other" category, whereas the entire assembly including the shaft and attached blades would be classified here.

As this is a leaf node within the HTS structure, there are no further subcategories. Therefore, classification within 8406.90.45.40 relies on confirming that the imported item is indeed a rotor, spindle, or a complete rotor/spindle assembly intended for use in a steam or vapor turbine. The focus remains on the inherent function and design of these components as the primary means of generating rotational energy within such turbines.