ARB Bearings
ARB Bearings is India’s leading bearing manufacturer company. The company was incorporated in 1990 and its headquartered at Delhi.
Thursday, 30 March 2017
Sunday, 19 March 2017
Thursday, 9 March 2017
Learn about new ideas for 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.
