Oil-out conditions, or conditions
in which an aircraft is
operating without any oil in its
gearbox or transmission, are
devastating for an aircraft's
hardware. Even the sturdiest gears
usually can't last 30 minutes under such
conditions before they catastrophically
fail, and the whole system usually follows shortly after. That doesn't leave pilots with a whole lot of time to find a suitable location to land in the case of an oil-out emergency.
This paper addresses the lubrication of helical gears - especially
those factors influencing lubricant film thickness and pressure.
Contact between gear teeth is protected by the elastohydrodynamic
lubrication (EHL) mechanism that occurs between nonconforming
contact when pressure is high enough to cause large
increases in lubricant viscosity due to the pressure-viscosity
effect, and changes of component shape due to elastic deflection.
Acting together, these effects lead to oil films that are stiff
enough to separate the contacting surfaces and thus prevent
significant metal-to-metal contact occurring in a well-designed
The oil industry is (pardon the pun) tanking. That may conjure up horrific images of other industries following suit in a domino effect of collective collapse into the overabundant oil slick the industry is currently drowning in, but not everyone is getting knocked down alongside the oil sector.
Historically, wind turbine gearbox failures have plagued the industry. Yet an effective oil analysis program will
increase the reliability and availability of your machinery, while minimizing maintenance costs associated with oil change-outs, labor, repairs and downtime. Practical action steps are presented here to improve reliability.
When it comes to purchasing gear lubricants, many people on both the sales and purchasing side decide to play the numbers game. The person with the most numbers, or the biggest numbers, or the lowest numbers, must have the best product - right? Wrong; gear oil selection is not a game, and numbers alone cannot determine the right product for an application.
The October 2011 issue of Gear Technology featured the article “Low-Distortion Heat Treatment of Transmission Components,” which covered
the combination of low-pressure
carburizing and high pressure gas quenching in an automotive environment. Here, heat treating expert Dan Herring explains why oil quenching is an appropriate choice for many applications.
A study was performed to evaluate fault detection effectiveness as applied to gear-tooth pitting-fatigue damage. Vibration and oil-debris monitoring (ODM) data were gathered from 24 sets
of spur pinion and face gears run
during a previous endurance evaluation