Posted by & filed under Bearings, Reliability, Windpower.


Join Rob Budny, well-known bearing and gear expert, and president of RBB Engineering, and Rick Brooks, manager of Wind Energy Aftermarket at Timken, as they discuss why case carburized bearings do matter for wind turbine applications.

In this webinar you will learn about:

  • Review a case study of field experience demonstrating the increased reliability of case carburized bearings
  • Learn about the common bearing failures in wind turbines
  • Understand the technical difference in bearing heat treatment methods

Rob Budny, President, RBB Engineering
President at an engineering consulting company offering comprehensive design and analysis services to the rotating equipment industry, with a focus on wind turbines. The company provides due diligence services, mechanical design, gear and bearing analysis, finite element analysis, failure analysis, RCA and corrective action design and implementation, component redesign, and develops optimal operations and maintenance practices.


Richard (“Rick”) Brooks, Manager – Wind Energy Aftermarket, The Timken Company
As Manager – Wind Energy Aftermarket, Rick Brooks is responsible for Timken’s wind energy business including bearings and related products for wind turbine maintenance and reliability. He was named to this position in 2011. In 21 years with Timken, Brooks has held positions in sales, information technology and business development for the company’s condition monitoring systems business. Brooks also previously managed Timken’s field reliability services in the United States, and is a Certified Maintenance and Reliability Professional.


Register for the free webinar here

Posted by & filed under Bearings, Failure Analysis, Reliability, Windpower.

Pitch Bearing Ellipse Spill

Pitch Bearing Ellipse Spill


RBB Engineering president Rob Budny will be presenting a webinar on wind turbine pitch bearing reliability on Thursday, July 14th, at 2:00 PM EDT. Rob will be joined by two experts from Kaydon, and the webinar will be moderated by Paul Dvorak of Windpower Engineering and Development. During the webinar, we will be sharing information on what causes pitch bearings to fail, along with steps owners can take to extend the life of their pitch bearings. The webinar will cover pitch bearing failure modes such as false brinelling, ellipse spill, and ring cracking. The importance of selecting the correct grease in maximizing the life of pitch bearings will be covered as well. Register today for the free webinar using the link here.





Posted by & filed under Bearings, Failure Analysis, Reliability, Windpower.

The root cause of wind turbine main bearing failures in a certain drivetrain arrangement used by many wind turbine manufacturers has become one of the costliest sources of unplanned maintenance for many wind turbine operators. Failure rates vary widely, and depend on factors such as wind turbine model, rotor diameter, main bearing manufacturer, and site wind conditions. As the root cause mechanism of the failures has become more well understood, so have means of detecting failures well in advance, along with means of reducing the number of failures and delaying their onset. The drivetrain arrangement which is prone to these failures is known as a “3 Point Mount”, and is illustrated in Figure 1.

3 Point Mount Drivetrain

Figure 1. 3 Point Mount Drivetrain (Source: NREL)

The configuration is called a 3 point mount because the gearbox is supported in three locations, one on the main bearing and two on the gearbox torque reaction arms. The main bearing in this configuration is known as a Spherical Roller Bearing, often abbreviated as SRB. SRBs are used successfully in many applications, and have many advantages over some other bearing types, namely a high radial load capacity, and most importantly, the ability to tolerate relatively large misalignments. However, in addition to the advantages offered by SRBs, they have some disadvantages as well. One disadvantage is that SRBs require a relatively high ratio of radial load to axial load. Another is that the design has high levels of sliding due to a phenomenon known as Heathcote slip. This means that large segments of the bearing rollers are both rolling and sliding along the bearing rings. The sliding portion of the contact results in high rates of wear, and is a risk factor in a gear and bearing failure mode known as micropitting, which is very common in wind turbine gears and bearings. These two disadvantages combine to result in the high rates of failure of SRB main bearings in 3 point mount configurations. The thrust loads on a wind turbine rotor vary with wind speed, and can be very large. By design, load in the bearing is supposed to be carried by both the upwind and downwind rows of rollers in the SRB. If the thrust load is too high, the downwind rollers carry all of the load, and the load is concentrated on the end of the roller. This condition results in micropitting damage to the bearing, which generates metallic particles. Figure 2 shows a typical example of a damaged SRB main bearing.

Figure 2 Damaged SRB

Figure 2. Damaged SRB Main Bearing (Source: Timken)

The metallic debris particles generated by the micropitting contaminate the grease in the bearing, and result in abrasive wear, which generates even more particles, further increasing the rate of wear, and ultimately resulting in failure of the bearing. As these failures have become more common, operators have developed several ways of detecting damaged bearings. Identifying damaged bearings in advance of complete failure can result in large cost savings. If a large site has more than one damaged bearing, they can all be replaced with a single crane visit, therefore avoiding the cost of crane mobilization for each and every damaged bearing. There are three basic methods which can be used to identify damaged main bearings:
1. Main bearing temperature trends
2. Main bearing condition monitoring data
3. Main bearing grease analysis
In addition to detection, there are steps owners can take to reduce the rates of failure of main bearings. The most important, and cost effective, step than an owner can take is to ensure that the bearing is greased frequently, and with an adequate amount of grease. Many owners have found that the amount of grease specified by the turbine OEM to be added to the bearing at each maintenance period is not sufficient, and have increased the amount of grease that they are adding to the bearing during maintenance. Some owners have also found that a grease other than what was originally specified by the OEM provides better protection to the bearing. Note that changing the amount and type of grease can have negative consequences as well, and any change must be made with the participation of the bearing and grease supplier, and such changes should be validated on a small number of turbines before the change is rolled out to an entire fleet. If a bearing has been shown to be damaged, either through monitoring of the bearing temperature data, through a grease analysis, or a bore scope inspection, a thorough flush of the grease in the bearing and a replacement with new grease has been shown to be effective in significantly extending the life of the bearing. The reason for this extension of life of the bearing is that the metallic debris generated by the damaged bearing, which causes abrasive wear, is removed from the bearing by the purge, thus reducing the rate at which the damage progresses. If a bearing has failed, and needs to be replaced, several bearing companies have developed replacements which are designed to be resistant to micropitting damage. In most cases, the replacement bearing is an SRB that has been specially engineered to improve its performance in wind turbine main bearing applications, usually through a combination of bearing geometry changes and the application of wear resistant coatings. One company however, has developed a type of taper roller bearing known as a TDI (taper double inner) that is a drop in replacement of the original SRB. The TDI bearing has a number of design advantages over the original SRB, including less sliding and skidding, and increased stiffness, which helps improve gearbox life.
SRB mainshaft bearing failures are costly, and not infrequent. However, as is typical with many wind turbine reliability issues, as the root cause factors responsible for the failures are identified, steps that owners can take to reduce the rate of failures are developed. This article provides an overview of the root cause factors responsible for SRB bearing failures, how damaged bearings can be identified well in advance of failure, and steps that owners can take to reduce the number of failures of this type.

Posted by & filed under News, Windpower.

Windpower Conference


RBB Engineering will be a featured exhibitor at the 2016 AWEA Windpower Conference and Exhibition May 23-26 in New Orleans. Use the link below to see the location of our booth in the convention center. Be sure to stop by to learn more about how RBB Engineering is helping wind operators reduce cost and increase reliability. Contact us at to schedule a meeting during the conference. Exhibit hall map.


Posted by & filed under Bearings, Failure Analysis, News, Reliability, Windpower.

RBB Engineering is attending the AWEA O&M Seminar at the Hotel Del Coronado in Coronado, California February 8th through 10th. RBB Engineering president Rob Budny will be giving a presentation on pitch bearing reliability during the seminar. You can learn more about Rob’s talk here. To set an appointment for a meeting during the seminar, please contact us at Please also plan to stop by our booth, where we will have several interesting gear and bearing failure specimens, and we will be raffling off a laminated Gear Failure Atlas Poster. We will also be unveiling our new visual brand identity material, please stop by and tell us what you think.


Posted by & filed under News, RBB Blog, Windpower.

RBB Engineering has announced that it will provide support to WEG in the development of WEG’s next generation wind turbine technology. RBB Engineering support will include design due diligence, specification development, supplier selection, and other technical tasks. Rob Budny, President of RBB Engineering, commented: “It is a real pleasure to be working with one of the world’s leading industrial companies as they continue their entry into the wind market, building on the success they have achieved with the AGW 2.1. We look forward to using our expertise to support WEG in the development of what will surely be an extremely reliable and cost competitive wind turbine”. Haral Serafini, Turbine Project Coordinator for WEG commented: “RBB Engineering has supported WEG by providing guidance on best practices for the design, manufacture, and qualification of wind turbines, which are complex systems that demand cross functional engineering interaction. RBB has already provided great value in the areas of cost optimization, reduced warranty costs, and conceptual design”.

Posted by & filed under News, Windpower.

WEG 2.1 MW wind turbine in commercial operation

WEG 2.1 MW wind turbine in commercial operation

An article in Recharge News discusses a 2.1 MW wind turbine currently in production by WEG, and describes a 3.3 MW turbine currently under development. The contributions of RBB Engineering to both turbines are called out in the article. You can see the article here:

Posted by & filed under Bearings, Failure Analysis, News, Publications, Reliability.

Bisson Award 1

RBB Engineering learned today that a paper on white etch cracking that was co-authored by Rob Budny won the Edmond E. Bisson award for best paper published by the STLE in 2014. The lead author of the paper was Bob Errichello, and Bob deserves the majority of the credit for the paper, which has been very influential in advancing the understanding of how white etch crack bearing failures can be prevented. Rainer Eckert of Northwest Labs was also a co-author of the paper.