COLLARIN EJE 50mm. STD (ZN)

Function and technical context

The 50 mm standard size (STD) shaft collar with zinc protection is a component of the vessel's underwater transmission line, whose main function is to retain and axially position the tail shaft within the hull, preventing unwanted longitudinal displacements during propulsion. It works on the external transmission system, in close collaboration with the stuffing box, shaft bearings and stern tube, maintaining correct alignment between the engine and propeller. The incorporation of zinc as a sacrificial material or coating in this collar also fulfills a galvanic anticorrosive function, protecting both the part and the adjacent metal components of the shaft against the electrochemical attack of salt or brackish water. If the collar fails or shows excessive wear, axial play may occur in the shaft, abnormal vibrations, accelerated wear of the stuffing box and, in severe cases, water entering the hull through the area of ​​the shaft passage.

When to replace this part?

The most common symptoms that indicate that the shaft collar needs inspection or replacement are: noticeable vibration in the shaft line while underway, clunking or knocking in the aft compartment, and visible wear or advanced corrosion of the sacrificial zinc indicating that the galvanic protection has been exhausted. It is recommended to inspect the axle collar at each annual grounding or during seasonal maintenance, checking the condition of the zinc, the tightness of the fixing screws and the absence of axial play. Replacing the collar preventively when the zinc is consumed by more than 50% or when any play in the shaft is detected prevents breakdowns at sea and extends the useful life of the stuffing box and adjacent bearings.

Compatibility table