Ball Bearing Provides Sealing And Lubrication

Baldor Electric has launched a Dodge-brand mounted ball bearing incorporating sealing and lubrication functions. Dodge Ultra Kleen ball bearings can extend equipment lifetimes in harsh, washdown-duty operating environments, such as food and beverage processing. They employ a 100 per cent stainless-steel bearing insert and feature a patented sealing system and a ball retainer that maintain lubrication and prevent washout in wet operating environments.

The new sealing system, Quadquard, consists of two patented features: a triple lip seal and a rubberised flinger. The triple lip seal offers three points of contact, keeping the lubricant in and contaminants out. This design maximises sealing with a minimal amount of drag, according to the company. The rubberised flinger is a moulded nitrile rubber component that is bonded to the flinger surface, providing an additional barrier to contaminants.

The rubber-baffled design on the external surface of the flinger enhances the removal of liquid as it rotates, while grease chambers on the internal surface of the flinger prevent lubricant from exiting the bearing. A new two-piece ball-retaining cage, called Maxlife, creates a grease compartment around each of the rolling elements. The compartments provide constant contact between ball and grease so an oil film always exists to prevent wear and to minimise friction and heat.

The compartmental construction holds in the grease and prevents it from being washed out. This design extends the life of the bearing and requires less frequent relubrication than standard designs, according to the company. A 65-degree spacing of the setscrews is intended to provide excellent locking force without compromising the strength of the inner ring, while a stainless anti-rotation pin prevents the insert from rotating in the housing.

The stainless housing is made with 300 grade steel. Polymer-housed versions have an added antimicrobial agent that retards bacteria and fungus growth. Both housing styles contain all-stainless hardware and fittings, as well as stainless-steel inserts. All versions feature a solid, flat base that has no cavities or areas that can provide a site for bacterial growth. For additional protection, the housings are machined with a groove to accept a snap-on polymer end cover to cover exposed, rotating shafts and create safer working conditions.

These covers incorporate a drain hole to prevent moisture build-up. Dodge Ultra Kleen bearings are offered in a variety of stainless-steel and polymer housings. The range is available in a range of imperial and metric sizes, from 20mm to 50mm.

Pitch Gears With Intelligent Shaft Sealing

Simrit has developed a radial-shaft seal system featuring a leakage sensor that allows for telediagnosis of the shaft seal and automatically sends a signal when the seal's wear limit is reached. With the help of these intelligent shaft seals, Wittenstein alpha has maximised the service life and service intervals of its pitch gears for rotor adjustment. Pitch gears are key components in wind turbines around the world.

They are used to adjust the pitch of the rotor blades, which in turn changes the aerodynamic efficiency of the turbine. Thanks to pitch gears, wind turbines can be operated at the optimum pitch until the rated power of the generator is reached. If the maximum generator torque is exceeded, the speed is adjusted by changing the pitch of the rotor blades. If performance remains constant, pitch gears allow wind turbines to operate continually at the optimum operating point.

One pitch gear per rotor blade is attached directly to the hub by screws. Wittenstein alpha has optimised the pitch gear for 1.5MW wind turbines and designed it to cope with approximately 50,000 operating hours over a 20-year period. To achieve optimum service intervals and maximum service life for these pitch gears, the specialists at Wittenstein alpha opted for a Simrit radial shaft seal with condition-monitoring function.

The outstanding advantage of this shaft seal, which is subjected to extreme stress during operation, is that it keeps the turbine operator informed of its serviceability. This means that the rotary shaft seal - which, for physical, tribological or chemical reasons, is always a part subject to wear - is only replaced when absolutely necessary.

If the sealing function of the radial shaft-seal begins to deteriorate at the end of its service life, the leakage is instantly absorbed by a leakage collector. An integral sensor in the sealing system identifies the leakage and generates a signal that is then evaluated by a programmable electronic unit. Once the first leakage has been registered and the progression of the leakage has been automatically evaluated, a message is sent to the operator or the service expert at the end of a freely programmable interval.

The system can be individually adjusted to suit the required leakage tolerances of the component manufacturer or the turbine operator. The programmable electronic unit can easily be integrated into existing monitoring systems. From there, the digital status signals can be sent by SMS, internet or telephone to the defined recipient. This means that wind-turbine operators and service companies can check the operating status of the sealing system at any time by means of remote data retrieval.

It also means that the replacement of the sealing system can be planned on the basis of the size of the leakage or can be done during regular servicing without the need for any additional turbine downtime. This means it is no longer necessary to replace seals 'just in case'. This in turn makes it easier to plan the servicing of wind turbines and allows operators to minimise downtime and costs.