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Rheology models express the way tribological conditions translate to shear stress of the lubricant and friction force on the interacting surfaces. Due to the complexity of the lubricant rheology, the friction coefficient is usually obtained experimentally either under the same operating conditions or by curve fitting in a properly chosen friction map. The current study aims at determining the rheological parameters of a lubricant based on friction measurements carried out on a commercial, readily available ball-on-disc machine.
This issue, we're pleased to present our annual Buyers Guide. It's our comprehensive directory of suppliers of mechanical components, including gears, bearings, motors, couplings, clutches, brakes, gear drives and more.
While metal-to-plastic parts conversion actually began way back in the Fabulous Fifties, think toys, household products, etc., it is only in more recent years that plastic conversion has gained a firm foothold in the more strength- and lifetime-demanding applications such as aerospace, under-the-hood automotive, motors, valves, bearings and, as they say, much more.
Sustainability is becoming one of the most important aspects within the power transmission business. Users demand low-maintenance drive systems with as little disruption as possible, and expect lifetimes of more than 10,000 hours. Approximately 40 percent of long-term gearbox leakages can be traced back to poor interaction between the radial shaft seal (RSS) and the lubricant. Thus, it becomes essential to analyze the tribological system as a whole, which includes the gear oil, seal grease (if required), elastomer material and design, and the shaft.
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.