COLLARIN EJE 25mm. STD (ZN)

Function and technical context

The 25mm shaft collar is an axial positioning and retaining element that works directly on the boat's drive shaft, keeping it in its correct longitudinal position within the propulsion assembly. Su función es evitar el desplazamiento axial del eje propulsor, garantizando que la hélice y los demás componentes del tren de transmisión mantengan la alineación y las tolerancias de trabajo previstas por el fabricante. Made of zinc (ZN), it also acts as a galvanic protection element, sacrificing itself to electrolytic corrosion to preserve the most expensive metal parts of the transmission system. A collar in poor condition compromises the integrity of the stern tube seal, can generate abnormal vibrations in the shaft and cause premature wear in the support bearings.

When to replace this part?

The most common symptoms of a deteriorated shaft collar are: noticeable vibrations in the horn or bottom of the hull during navigation, visible axial play in the shaft when manually inspected, and obvious signs of corrosion or mass loss in the zinc collar. As it is a galvanic sacrificial component, it is recommended to inspect it at the beginning of each season and replace it when it has lost approximately 50% of its mass, or at least once a year in boats that remain in the water. Replacing the collar preventively at each annual tune-up is the best guarantee to avoid damage to the shaft or horn that would force you to take the boat out of season.