Staring down the shaft of yet another failed bearing at the worst possible time is nowhere an engineer wants to be.
So, what goes into the decision-making process to select the right water lubricated bearing or seal? Unfortunately, there is no chart available showing bearing wear rates to help guide operators to the most reliable option. The process can be complicated when considering cost, availability, shaft conditions, water conditions, alignment issues, thermal expansion, marine growth, and environmental impact.
When it comes to ships, operators have several options: Babbitt white metal that require seals and oil, both are problematic for leaking and spilling oil. Polymers, plastics, and composites all are prone to seizures, hydrolysis and wear from crustacean invasion that turns the shells into a calcium paste causing premature wear. Lignum vitae that operates on a mixed mode of lubrication allowing the shaft to bear directly on hard cold starts, then goes hydrodynamic as speed increases and requires no oil, seals, or possibility of wiping/smearing or melting onto the shaft. This is due to mother nature’s ability of building the wood molecule by molecule cell by cell leaving no voids vs. mixing a plastic or polymer that leaves voids of structure and lubricity leading to failure.
Shipping is a conservative business that considers how reliable the bearing will be in service. Currently there are approximately 20 different polymers in play, that begs the question; How long has the bearing been proven in service? Many manufactures point to recent tests in a laboratory environment with polished samples in de-ionized water as proof their bearing will perform. Does the test replicate the real world the bearing will work in and how does any laboratory test guarantee long term performance in warm water, cold water and abrasive water? Another question is how many excuses will you accept?
Lignum Vitae North America has engineered new cost effective, easy to install systems. Our staves and stern tubes range from 4”/100mm to 50”/1300mm and larger and require no freezing or special tooling. Lignum vitae conforms to any shaft condition due to tremendous tenacity of homogeneously woven fiber surrounded by guaiac resin that will wear itself into the current shaft/journal condition. Removing and turning a shaft will become a thing of the past.
Lignum vitae has secured its position as the world’s most dependable water lubricated bearing after 168 years of flawless operation in thousands of vessels worldwide. It has been in continuous service since the first rotating shafts replaced sail vessels. In fact lignum vitae is the only water lubricated bearing that has served in pre WWI ships, every WWII ship, including Nuclear submarines, Aircraft carriers, Victory ships and has recently been recertified by ABS to qualify for future Frigates, Destroyers and Icebreakers.
Its rich history of reliability was central to the Indian Navy’s decision to use lignum vitae to extend the service life of the Aircraft carrier INS Vikramaditya after receiving 33 years’ service with the previous set of lignum vitae bearings. LVNA supplied 16 bearings weighing 5,450 lbs. for the 4 shafts of the INS Vikramaditya from purchase order to shipment in just 7 days.
There is no number of slick ads, fast names, bright colors, or flavor of the day bearing that can replace tried and true lignum vitae that has performed for nearly 2 centuries. We are proud to be leading the way with a sustainable supply of renewable lignum vitae that exceeds every environmental standard, avoids all legal, EPA and sub chapter M requirements.