Thursday, 20 April 2017
Thursday, 30 March 2017
Sunday, 19 March 2017
Thursday, 9 March 2017
latest Ideas about the gearbox bearings
Gearboxes have long taken blame as the typical cause for a failure, and for good reason. Many gearboxes fail to pass the five-year mark without need for component repairs or full replacement. But when the industry first got its start, few considered the high winds, vibration, or environmental conditions that turbines must withstand.
“At the time, the same basic gearboxes used at cement mills or in industrial applications were simply hauled up some 300 feet in the air, place inside a nacelle, and expected to work to the same standards,”
Nowdays gearbox is specifically designed for its intended application, such as for use in a wind turbine. However, the “gearbox legacy design issue,” as Brooks calls it, has led to years of lessons learned for the Bearings industry that continue to this day. “For example, Nowdays a gearbox designed for a brand-new turbine today is exceptionally better than one even made five or seven years ago because of the accumulative knowledge engineers have gained and continue to gain over time.”
Although this progress has led to more durable gearboxes capable of better handling the harsh conditions turbines face, there is still one fundamental challenge. This challenge primarily relates to differences in speed, according to bearings industry. “A turbine’s rotor may be turning at about 15 rpm but the generators are going 1,500 rpm, which represents an increase of 80 to 100 times,”
Typically, a designer would select different types of bearings and lubricants for low and high-speed applications. “But here you have one gearbox handling different speeds and loads with one type of lubricant. This isn’t the best scenario.” the turbine design would make use of two different gearboxes — one for low and one for high speeds — but that’s too complicated and not economical or feasible for the industry.
“Nevertheless, you’re still stuck with a machine that must deal with compound speeds in a harsh and complex environment, while facing high dynamic loads. Over time that leads to failures.” the industry is likely never going to fully overcome this challenge in gearbox-driven turbines, but quality bearings properly maintained are one step in mitigating turbine downtime.
High-speed bearings
Although there is some truth to the statement that a gearbox is only as good as its components, even the highest quality equipment has a limited life expectancy in the industry. Bearings offer no exception.
Bearings serve numerous roles in a wind-turbine gearbox and show different failure rates based on their position. For example, planet carriers and low-speed bearings work with some thrust load but generally have a low failure rate.
Planetary bearings
While high-speed bearings have the highest failure rates and low-speed bearings have some of the lowest, planetary bearings rank somewhere in between. Life expectancy is about 10 years before failures typically set in, although this can vary depending on the make and model of the gearbox.
“But regardless of gearbox model or bearing type, we generally find that deflections and loading problems are the primary issues with planet bearings”, “This is because of the variable loads that come into the gearbox and cause undesired deflections. This is made worse when the main bearing wears and lets even more thrust and load than intended into the gearbox. Over time, these forces take a toll.”
Integrated bearings
A bearing typically has three pieces: the rollers, an inner race that is pressed onto a shaft, and an outer race that is pressed into the gear bore. But now there are options that integrate the inner race with the shaft or the outer race with the gear, or both, into one solid component. “Integrating essentially machines the bearing’s outer race into the inner bore of the gear,”
An integrated bearing reduces the total number of components in the assembly by directly machining bearing races into the surrounding components of a gearbox. It is an option for cylindrical and tapered gearbox planet bearings.
“In some ways it brings complexity into the manufacturing process because bearings are not made at gear plants nor are gears made at bearing plants,” says Brooks. “But there are a lot of advantages to integrating the two.” Most notably: integrated bearings show improved performance and greater power density.
“At the time, the same basic gearboxes used at cement mills or in industrial applications were simply hauled up some 300 feet in the air, place inside a nacelle, and expected to work to the same standards,”
Nowdays gearbox is specifically designed for its intended application, such as for use in a wind turbine. However, the “gearbox legacy design issue,” as Brooks calls it, has led to years of lessons learned for the Bearings industry that continue to this day. “For example, Nowdays a gearbox designed for a brand-new turbine today is exceptionally better than one even made five or seven years ago because of the accumulative knowledge engineers have gained and continue to gain over time.”
Although this progress has led to more durable gearboxes capable of better handling the harsh conditions turbines face, there is still one fundamental challenge. This challenge primarily relates to differences in speed, according to bearings industry. “A turbine’s rotor may be turning at about 15 rpm but the generators are going 1,500 rpm, which represents an increase of 80 to 100 times,”
Typically, a designer would select different types of bearings and lubricants for low and high-speed applications. “But here you have one gearbox handling different speeds and loads with one type of lubricant. This isn’t the best scenario.” the turbine design would make use of two different gearboxes — one for low and one for high speeds — but that’s too complicated and not economical or feasible for the industry.
“Nevertheless, you’re still stuck with a machine that must deal with compound speeds in a harsh and complex environment, while facing high dynamic loads. Over time that leads to failures.” the industry is likely never going to fully overcome this challenge in gearbox-driven turbines, but quality bearings properly maintained are one step in mitigating turbine downtime.
High-speed bearings
Although there is some truth to the statement that a gearbox is only as good as its components, even the highest quality equipment has a limited life expectancy in the industry. Bearings offer no exception.
Bearings serve numerous roles in a wind-turbine gearbox and show different failure rates based on their position. For example, planet carriers and low-speed bearings work with some thrust load but generally have a low failure rate.
Planetary bearings
While high-speed bearings have the highest failure rates and low-speed bearings have some of the lowest, planetary bearings rank somewhere in between. Life expectancy is about 10 years before failures typically set in, although this can vary depending on the make and model of the gearbox.
“But regardless of gearbox model or bearing type, we generally find that deflections and loading problems are the primary issues with planet bearings”, “This is because of the variable loads that come into the gearbox and cause undesired deflections. This is made worse when the main bearing wears and lets even more thrust and load than intended into the gearbox. Over time, these forces take a toll.”
Integrated bearings
A bearing typically has three pieces: the rollers, an inner race that is pressed onto a shaft, and an outer race that is pressed into the gear bore. But now there are options that integrate the inner race with the shaft or the outer race with the gear, or both, into one solid component. “Integrating essentially machines the bearing’s outer race into the inner bore of the gear,”
An integrated bearing reduces the total number of components in the assembly by directly machining bearing races into the surrounding components of a gearbox. It is an option for cylindrical and tapered gearbox planet bearings.
“In some ways it brings complexity into the manufacturing process because bearings are not made at gear plants nor are gears made at bearing plants,” says Brooks. “But there are a lot of advantages to integrating the two.” Most notably: integrated bearings show improved performance and greater power density.
Thursday, 23 February 2017
History of the Projector
we eat, breathe, and live presentations. We also acknowledge that our unusual lifestyles would never have existed without the projector: The Mother of All Presentations. Let’s pay our respects by learning a bit more about the projector.
An Ancient History
Projecting images onto a larger surface is an old trick; the first known instance of this was recorded in a drawing by Johannes de Fontana in 1420. In which, a nun holds a lantern with a small translucent window that projects an image of a devil. Leonardo da Vinci also drew a similar device, later known as a magic lantern, in 1515.
But who invented the actual, official magic lantern? And when? To find out the truth, you will need a time machine and a boxing ring to let all of these potential inventors fight it out:
Pierre Fournier – 1515, France
Giovanni Battista della Porta – 1589, Italy
Athansius Kircher – 1646, Germany
Christiaan Huygens – 1659, Holland
Thomas Rasmusser Walgenstein – 1660, Denmark
Claude Millet – 1674, France
These early projectors were often used for devious purposes, nicknamed “lantern of fright” because they were adopted by magicians to “summon ghosts” or appear in two places at once. Not exactly the stuffy tools of boardrooms we use today.
Getting Civilized
In the late 1800s, magic lanterns using oil lamps began to be adopted by photographers, lecturers, and the general public rather than the spooky magician crowd. They were also wisely renamed “opaque projectors.” As time progressed, incandescent light bulbs with halogen lamps took the place of outdated light sources. These opaque projectors (as we know) were great teaching tools. For example, Chicago’s public school system had around 8,000 opaque projectors by the end of World War I.
Overhead projectors eventually replaced the opaque projector. In World War II, soldiers were trained from presentations using a version of an overhead projector. Through the 50s and 60s, schools, businesses, and even police departments relied on overhead projectors to share information.
Our Fancy Future
Overhead projectors evolved into multimedia projectors when digital images took over in the 20th century. On May 22nd, 1990, Microsoft launched a slide-based presentation computer program. We know it today as our beloved PowerPoint, though it was originally called “Presenter” by developer Dennis Austin.
The goal of PowerPoint was to have a number of pages or “slides” that could represent the transparencies used in an overhead projector. It was more efficient than other forms of visual aid such as whiteboards or chalkboards, and served many kinds of audiences and presentation needs. The projector game had changed forever, signaling the end of overhead projectors and physical slide sheets.
Today you can buy portable, wireless, and digital projectors for less than you might spend on a good pair of jeans. However, we still tip our hats to the projectors of yesteryear, and all the ingenuity it took to create them.
An Ancient History
Projecting images onto a larger surface is an old trick; the first known instance of this was recorded in a drawing by Johannes de Fontana in 1420. In which, a nun holds a lantern with a small translucent window that projects an image of a devil. Leonardo da Vinci also drew a similar device, later known as a magic lantern, in 1515.
But who invented the actual, official magic lantern? And when? To find out the truth, you will need a time machine and a boxing ring to let all of these potential inventors fight it out:
Pierre Fournier – 1515, France
Giovanni Battista della Porta – 1589, Italy
Athansius Kircher – 1646, Germany
Christiaan Huygens – 1659, Holland
Thomas Rasmusser Walgenstein – 1660, Denmark
Claude Millet – 1674, France
These early projectors were often used for devious purposes, nicknamed “lantern of fright” because they were adopted by magicians to “summon ghosts” or appear in two places at once. Not exactly the stuffy tools of boardrooms we use today.
Getting Civilized
In the late 1800s, magic lanterns using oil lamps began to be adopted by photographers, lecturers, and the general public rather than the spooky magician crowd. They were also wisely renamed “opaque projectors.” As time progressed, incandescent light bulbs with halogen lamps took the place of outdated light sources. These opaque projectors (as we know) were great teaching tools. For example, Chicago’s public school system had around 8,000 opaque projectors by the end of World War I.
Overhead projectors eventually replaced the opaque projector. In World War II, soldiers were trained from presentations using a version of an overhead projector. Through the 50s and 60s, schools, businesses, and even police departments relied on overhead projectors to share information.
Our Fancy Future
Overhead projectors evolved into multimedia projectors when digital images took over in the 20th century. On May 22nd, 1990, Microsoft launched a slide-based presentation computer program. We know it today as our beloved PowerPoint, though it was originally called “Presenter” by developer Dennis Austin.
The goal of PowerPoint was to have a number of pages or “slides” that could represent the transparencies used in an overhead projector. It was more efficient than other forms of visual aid such as whiteboards or chalkboards, and served many kinds of audiences and presentation needs. The projector game had changed forever, signaling the end of overhead projectors and physical slide sheets.
Today you can buy portable, wireless, and digital projectors for less than you might spend on a good pair of jeans. However, we still tip our hats to the projectors of yesteryear, and all the ingenuity it took to create them.
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