Motiivihöyrysuutin

Motiivihöyrysuutin, also known as motive steam nozzle in English, is a component primarily found in steam locomotives. Its function is to efficiently entrain and exhaust the waste steam from the cylinders, accelerating it and directing it through the chimney. This process creates a vacuum in the smokebox, which draws air through the firebox, thus stimulating combustion and ensuring a strong draft for the boiler.

The design of the motive steam nozzle is critical for the overall performance of a steam locomotive. A well-designed nozzle optimizes the flow of steam, leading to better boiler efficiency and more power output. Conversely, a poorly designed or improperly adjusted nozzle can lead to steam "blowing" or short-circuiting, reducing draft and negatively impacting the locomotive's steaming capabilities.

There are various types of motive steam nozzles, including single, double, and triple designs, each with its own advantages and disadvantages. The choice of nozzle type and its dimensions often depend on the specific engine design, boiler characteristics, and desired operating performance. Adjusting the nozzle’s opening, often referred to as the "blastpipe," allows engineers to regulate the draft and thus control the fire's intensity. This adjustment is a key aspect of managing a steam locomotive's performance during operation.