Stern Shaft Seal Lubrication Oil System

The stern shaft bushings of the stern shaft sealing device are made of high-chromium stainless steel, providing excellent corrosion and wear resistance. The sealing rings consist of imported Nitrile Rubber (NBR) from Japan combined with stainless steel springs. The lips offer excellent conformity, strong compensation capability, and high shock resistance, allowing effective isolation of two different media under high-speed and high-pressure conditions. This design effectively solves leakage problems caused by axial shaft movement, and offers advantages such as superior sealing performance, long service life, low power consumption, and easy installation. Additionally, it provides sand- and net-prevention functions, making it widely applicable for both radial and axial sealing of stern shafts on various inland vessels, coastal ships, ocean-going transport ships, and engineering vessels.

The lubricating oil system of the stern shaft sealing device is relatively simple. The stern tube, together with the forward and aft sealing devices, forms a sealed space filled with lubricating oil, in which the stern shaft and stern bearings are immersed. This constitutes a closed lubrication system. A gravity oil tank is installed 3–4 meters above the ship’s design waterline in the engine room and connected via a pipeline to the inlet pipe above the stern tube. The return oil pipe at the bottom of the stern tube allows oil to flow back to the gravity tank. The gravity oil tank serves to supplement and maintain the oil level in the stern tube, generate a certain pressure acting on the #3 sealing ring, and maintain a stable pressure differential between the internal lubricating oil and the external seawater. Additionally, the gravity tank facilitates venting, oil circulation, and heat dissipation.