The water-lubricated bearing are made with an outer bearing of brass (OT63) or technoplastic polyamide resin that has the advantage of neutralising electrolytic corrosion.
The inside of the bearings are coated with black nitrile rubber with the following characteristics:
Density = 1.23
Hardness = 70/75 shore
Tensile strength at break = 2,2 Kg/mm²
Elongation at break = 225%
Suitable for shafts with forward and reverse rotation.
The bearings are lubricated with water that forms a very thin film between the shaft and rubber of the bearings, and reduces the coefficient of friction to very low values. Never run dry because a high temperature would immediately damage the bearing. Make sure the rubber does not come into contact with harmful substances, such as grease or lubricating oil. The circulation water contributes to evacuating the heat from the inner surface of the bearing, whose temperature must never exceed 50/60°C.
Therefore, it is necessary to:
Leave a minimum clearance between the shaft and rubber bearing, which should vary depending on the diameter (0.10 to 0.30 mm).
Make sure the peripheral speed of the shaft does not drop below 0.2 m/sec.
Keep the necessary amount of circulating water by installing an independent sea cock.