Operating Conditions of the Stern Shaft Sealing Device

The operating conditions of stern shaft sealing devices are extremely harsh. During operation, in addition to being subjected to severe wear and the effects of high frictional temperatures, they are also exposed to river water containing silt and sand. For vessels with deeper drafts in particular, the stern shaft seal must withstand the pressure differential between higher external seawater pressure and the internal static pressure of the lubricating oil. Furthermore, when the propeller rotates, cantilever forces and uneven loads are generated, causing significant radial runout and eccentric motion of the stern shaft within the stern bearing.

In addition, the main engine frequently operates under both ahead and astern conditions, which often induces transverse and axial vibrations of the stern shaft during operation, thereby adversely affecting the sealing device. These working characteristics are highly unfavorable for maintaining an effective stern shaft seal. Moreover, once a stern shaft sealing device fails, it may not only cause lubricating oil leakage or generate large amounts of bilge water, polluting the marine environment, but also require the vessel to undergo dry-docking or slipway repair, disrupting normal operations. For these reasons, research and development on stern shaft sealing devices is of great necessity.