8412.90.90.25 - Of linear acting engines and motors

This HTS subcategory, 8412.90.90.25, specifically designates parts for linear acting engines and motors. These are mechanisms where the primary output is a straight-line motion, as opposed to rotary motion. Examples include pistons, cylinders, seals, connecting rods, and housings designed for reciprocating engines or linear actuators driven by pneumatic or hydraulic power. The classification hinges on the integral function of these components in producing or transmitting linear force and displacement.

Distinguishing this category from its sibling, 8412.90.90.35 ("Other"), is crucial. The sibling category encompasses parts for other types of engines and motors not specifically enumerated, such as rotary engines or other specialized mechanisms. Therefore, if a part is specifically designed for a linear acting engine or motor, it will fall under 8412.90.90.25, whereas general or non-linear specific engine and motor parts would be classified elsewhere.

As this is a leaf node within the HTS structure, there are no further subcategories to introduce. Classification at this level requires careful examination of the component's design and intended application. The defining characteristic is its direct contribution to the linear mechanical output of the engine or motor system.