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Slow speed operation of fan systems within the air handling
industry is generally performed due to two reasons: a coast
down operation is required for hot (induced draft) fans to
cool down before shutdown (often by using a turning gear),
and operational efficiency improvements can be achieved
during non-peak periods by slow speed operation using a
VFD. In either case, when these fans are supported by hydrodynamic
bearings, it is the oil film thickness developed from
the bearing-shaft interaction that limits the minimum speed
that can be maintained without causing premature wear and
bearing failure. This paper will present a brief overview of
lubrication theory and critical design parameters to achieve
slow speed operation.
Increasing pressure on many fronts is compelling mine operators to thoroughly examine every phase of their operations. Fluctuating demand
that whipsaws mineral prices, government-imposed environmental regulations and rising operating costs related to maintenance downtime all pose serious challenges for the mining sector. Add pressure from customers and stakeholders for more sustainable operations as well as union demands for higher wages, and you have a scenario that requires mine operators to exercise every possible option to
achieve more efficient operations.
Rolling-element bearings are high-precision components that need to be stored and handled carefully to perform as designed. Proper storage and
handling of a bearing before, during
and after installation is important because once debris enters a bearing, it
reduces the life.
Experienced operators can often
tell if a machine is not working
properly, on the basis that it does
not ‘sound right.’ The same principle can be applied — using modern electronics — to identify the exact cause of the problem.
Sensitive accelerometers can detect and analyze the vibrations from industrial equipment, highlighting problems such as misalignment
or bearing imbalance. The technique
is known as vibration analysis. It can
identify bearing failure in the very early stages, when there is a microscopic defect on the raceway, for example. The problem is that the
identifying signal is usually drowned out in all the other noise emanating from the machine.
I have a fairly straightforward question about a worm gear segment. But as of yet, I haven’t gotten a straight answer from any of the gear job shops I’ve approached about this job. Is there a "traditional" gear cutting method that can produce a ~180
degree enveloping worm gear segment when a feature on the back of the part will interfere with a complete rotation of the part? Or am I left with only the option of 4- or 5-axis surfacing with a CNC mill? I have presented this part to several well-known gear shops in the U.S. without a straight answer on how the part can be made. Any help you could offer would be appreciated.
In order to analyze the different gear
oils suitable for the lubrication of wind turbine gearboxes, five fully formulated ISO VG 320 gear oils were selected. In between the selected gear oils, four PAO base oils can be found: PAOR, PAOM, PAOC and PAOX. A mineral-based oil (MINR) was also included as reference.