COLLARIN EJE 38mm. STD (AL)

Function and technical context

The 38 mm aluminum shaft collar is an axial retention and positioning element for the transmission shaft in motor boat propulsion systems. It works in the transmission system, acting as a mechanical stop that prevents the longitudinal displacement of the propeller shaft within the stern tube or corresponding housing. Its correct installation guarantees that the shaft maintains the intended working position, ensuring alignment between the propeller and the motor and avoiding abnormal vibrations, clearances and premature wear in the shaft bearings. A collar in poor condition can cause uncontrolled axial movement of the shaft, which results in progressive damage to seals, bushings and the stern tube itself, with the consequent risk of water entering the hull.

When to replace this part?

The most common symptoms of a damaged shaft collar are: noticeable axial play in the propeller shaft when manually pushing and pulling the propeller, unusual vibrations transmitted to the hull during navigation, and visible wear in the contact area of the collar with the housing. At each grounding or seasonal maintenance, it is advisable to inspect the collar along with the rest of the components of the axle system—seals, horn and bearings—since the wear of one of these elements accelerates the deterioration of the others. Replacing the collar preventively during scheduled maintenance is significantly more economical than facing an emergency repair due to navigational breakdown.