Marine Link
Tuesday, September 26, 2017

Bently Nevada Looks to Perfect Bearing Technology

February 20, 2001

Bently Nevada Corporation, already known to the marine market as a leading supplier of monitoring and diagnostic products and services for the rotating and reciprocating machinery, is taking the next step in their evolution as a machinery information and knowledge company. The company's protection systems are no strangers to gas and steam turbine main propulsion units, turbine and diesel generators, as well as other critical service equipment such as cargo pumps and fans. Now Bently is moving ahead; not directly in monitoring the condition of machinery, but getting to problem root cause and improving the reliability of machines.

Donald Bently, President of Bently Nevada says, "Our field engineers and customers are constantly diagnosing machinery problems, and a large number of those problems stem from poor bearing designs. If our probes have taught me one thing, it is that current bearing technology is badly obsolete, and the market is long overdue for superior bearings. Hydrodynamic bearing technology simply hasn't progressed substantially in many years. I saw a need for improved technology and technical leadership in the area of bearings and stepped in. I'm offering bearings that reflect 21st century capabilities - not 19th century technology. I think the technology we have is the most important thing to happen to bearings in the last 100 years."

Applications for this new bearing technology range anywhere from steam and gas turbines, to the turbo-chargers on diesel engines, large pumps and fans, and even line shaft bearings.

Until now, the rotor dynamic properties of a machine were something you simply "lived with." Making deliberate changes to the machine's rotor dynamic characteristics meant at least two things: Removing the machine from service; and Physical modifications to the geometry of bearings, seals, blades, rotors, or support structures.

A benefit of Bently's ServoFluid technology is that it is designed to make possible a whole new generation of machines with adjustable rotor dynamic characteristics. In plain terms, adjustments can be made to the machine without removing it from service and physically modifying the rotor and associated items; eliminating downtime and minimizing maintenance costs. Pairs of bearings can be used to provide cantilevered support rather than the vertical-only support provided by traditional bearings. Designers are therefore able to use shorter rotors with smaller diameters, reducing the physical space requirement for the machines.

Since the ServoFluid Control Bearing (SFCB) uses a hydrostatic instead of hydrodynamic lubrication system, the design is not limited to petroleum-based lubricants. Lubricant materials that are more compatible to the process or environment, such as water, air or process fluids, can therefore be used. Improved efficiency is one benefit that results from this flexibility. The SFCB is an externally pressurized bearing, and contrary to conventional internally pressurized bearings that require sufficient fluid viscosity to internally develop a supporting pressure wedge, the SFCB's external pressurization of the lubricant allows use of low viscosity fluids, thus reducing the mechanical losses.

Machine problems such as high vibration and instabilities dissipate otherwise useful energy from the intended process. Proper application of the SFCB reduces these mechanical losses, allowing more efficient conversion of fuel to energy. Along with a reduction in mechanical losses, application of the SFCB enables optimizing of the machine's rotor dynamic performance which can extend machine maintenance intervals, in turn maximizing uptime. Additionally, application of an externally pressurized bearing nearly eliminates excessive wear due to frequent start-ups/shut-downs of machines typical in the marine environment.

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