Main Bearing Failures: Detection, Coatings, and Solutions with Malloy Wind

Allen Hall and Joel Saxum talk with Cory Mittleider from Malloy
Wind about the complex world of wind turbine main bearings. Cory
breaks down why traditional bearing coatings are failing in newer
turbine models and explores how electrical discharge, material
choices, and monitoring systems play crucial roles in solving these
costly failures. Dive into the technical challenges of detecting
problems in these massive, slow-moving components and learn what
operators should do during warranty periods to prepare for
long-term maintenance. Sign up now for Uptime Tech News, our weekly
email update on all things wind technology. This episode is
sponsored by Weather Guard Lightning Tech. Learn more about
Weather Guard's StrikeTape Wind Turbine LPS
retrofit. Follow the show
on Facebook, YouTube, Twitter, Linkedin and visit
Weather Guard on the web. And subscribe to Rosemary Barnes'
YouTube channel here. Have a question we can answer on the
show? Email us! Pardalote Consulting -
https://www.pardaloteconsulting.comWeather Guard Lightning Tech -
www.weatherguardwind.comIntelstor - https://www.intelstor.comWind
Energy O&M Australia Conference - https://www.windaustralia.com
Joel Saxum: Welcome to Uptime Spotlight, shining light on wind
energy's brightest innovators. Allen Hall: This is the progress
powering tomorrow. I'm your host, Allen Hall, joined by my co host,
Joel Saxum. Today, we're tackling a critical issue that's affecting
wind farm operators across the industry, main bearing failures and
the evolving solutions to combat them. Joining us is Cory
Mittleider business unit manager at Malloy Wind, who brings over 15
years of hands on experience in power transmission and bearing
technology. Cory has built his career at Malloy Electric where he's
become their go to expert for complex bearing challenges. His
journey from technical sales support engineer to wind business unit
manager has given him a unique perspective on the evolution of
bearing technology and the real world challenges faced by wind farm
operators. Malloy Wind, based in Sioux Falls, South Dakota, has
been at the forefront of developing solutions for wind turbine
bearing issues, particularly focusing on advanced materials. and
designs to combat common failure modes like peeling damage and
premature wear. Cory, welcome to the Uptime Wind Energy Podcast
Spotlight. Thanks for having me. You are our go to guy for Anything
bearing related. And as Joel and I travel around the United States
this summer, we ran into a lot of people with bearing issues and
now main bearing issues. And we've seen quite a bit in the press
this summer about main bearings and coatings on main bearings and
what is the right kind of main bearing to use and a lot of
operators looking at different solutions at the minute, and we
figured. Cory will know. So let's just ask Cory what his thoughts
were on main bearings and try to get a sense of what can be done.
Cory Mittleider: Yeah. We've definitely spent a lot of time looking
into main bearings, main bearing failures. Joel Saxum: So let's
dive into this, Cory, then what is the. Just for our users or
users, for our listeners can you give us the rundown basically of
what the main bearing is, where it sits in the turbine and what it
does? Cory Mittleider: On the wind turbine drivetrain, you've got
the blades and the rotor hanging out front, and then ultimately
that's connected to a shaft. Which then connects it to the gearbox
and the generator. And on that shaft, that's what we'll call the
main shaft. On that shaft, there is a really big pillow block. And
it's got the main bearing inside. So we'll call it the main
bearing, the main shaft bearing, a couple of different
nomenclatures there. But that's what helps support that load of
this very heavy drive train, but also connect it and allow the
rotation to generate the power from the turbine. Some turbines do
have two. main bearings on this main shaft. And most of them
installed in the U. S. have one. That's what we'd call a three
point suspension. The two main bearing ones we call four point
suspension. There are some other designs some direct drives and
stuff like that, but very small install, install base in the U. S.
So we're really talking about this type of configuration where
we're talking about main bearings most of the time. Joel Saxum:
Okay. So I'll ask you another really basic and simple question for
people like myself. There's a lot of people in the wind industry
that have never been uptower and have never seen these things, so
they may not know exactly what size and what kind we're looking at,
but, you've been in the wind industry for a while, Cory, so you've
seen some small ones, and now we're growing in from that one
megawatt, sometimes 500 you're in. South Dakota. So you've got some
Zahn Z50s and stuff out your door. Cory Mittleider: Yeah, we've got
some 750s out here. Joel Saxum: So there's, there are a lot smaller
in the main bearing size, but now we're getting all the way up to
the point where we're actually hearing of, like right now, GE is
one, one 6. 1 megawatt, 158s are being installed in Wyoming. So
we're getting to that larger size. What is the size of these things
look like? Cory Mittleider: Yeah, it's been fun to see the
trajectory on size. I remember one of the first main bearings I saw
in person was a shaft size. That's 12 inches. And coming from the
industrial bearing space, where a good size bearing is 4, maybe 5
inches. That thing was huge, right? I'm like, wow, look at that big
thing. Over the last 10, 11, 12 years now we're talking that mid
two megawatt range, we're talking 700 800 millimeter shaft sizes
that's about 30 inches. Shaft diameter. It's really tremendous to
see the size grow from another point of information, that shaft
size bearing weighs in at about 2, 500lbs. So 30 inch shaft size,
2, 500lbs, call it 50 inch on the OD about. So Joel Saxum: putting
this Cory Mittleider: into Joel Saxum: scale, right? Like I, I
drive a three quarter ton diesel truck. That truck on the hoof
weighs like 7, 700 pounds, 7, 800 pounds. So just three of these
bearings weighs as much as that three quarter ton truck sitting out
there in the park, in my driveway. That's insane, right? Just to
put that into scale. The scale, but I will, in the wind industry,
you get that conversation quite a bit. Like people don't realize
how big turbines are until you've stood underneath one. You can
drive by on the highway. Drive up I 35 in Iowa and you look out and
you're like, wow, they're cool looking. That's big. But then you
stand on the pad underneath one and you're like, whoa, this is a
different story. Because when we talk about this, that main bearing
supports a lot of weight, right? So you have blades, you have that
hub sitting out there. And these blades can be 20, 30, 40, 000
pounds. Each, right? So you're talking, this bearing, the weight
that's hanging out over the front of it easily can surpass a
hundred thousand, 150, 000 pounds that it's supporting. So they
become a massively critical element in the drivetrain. Like they're
very important to the whole mechanism. If these things start to
fail, which we've, Alan and I have been hearing in the field,
right? Oh, we've got main bearing problems. We've got main bearing
problems. This is not a trivial piece of kit to change out. Cory
Mittleider: No, and that's a really good point. You look at the
complexity of the system, the fact that to your point, this system,
when you drive down the interstate a little ways away, it's like,
Oh, that's big, but. Once you put your hands on this stuff, you
really start to appreciate just how big it is. And so one of the
the mid two megawatt main shaft bearings is a 750 millimeter shaft
size. This is the size of a roller from that main bearing. There's
maybe 60 of these. Joel Saxum: So if you're listening online,
rather than watching the YouTube version of this, you can see Cory
was, Cory, you can't see, but Cory was holding up a roller bearing
that is the size of, it's a larger than even a Coke can of just,
and this is just one of these elements. Cory Mittleider: Yeah.
Yeah. And there's quite a few inside. The other interesting thing
is there's a curvature to it, so it's not just like a Coke can, but
it's actually bulged in the middle. And, there's a lot of different
bearing types. Used just in any industry. And the thing that makes
this this main shaft bearing special is it's, they used in the
design primarily, but are called double row spherical roller
bearings. And those have been around for a long time. They were
invented in 1919. Very well defined from an envelope point of view.
But the benefit of this bearing type is that curvature of the
roller and the corresponding curvature of the raceway allows. for
some deformation and it'll accommodate what we call misalignment.
So you imagine you've got this a hundred plus thousand pound drive
train on the up in the air, it's 80, 90, a hundred meters in the
air on top of a stick in a cornfield, right? The environment is
changing constantly. Temperature, wind, weather, all this stuff.
The ability of that system to move a little bit is why you pick a
double row spherical type bearing. So that allows. confidence that
it will still carry the load effectively while still potentially
being able to move. So that's why the vast majority of mainshaft
bearings are in fact, this double row spherical type as well. Allen
Hall: So if you have different OEMs you'll see different
manufacturers for those same bearing types, right? That they're not
uniform. I haven't seen. Two manufacturers of bearings produce
really the same bearing. Everybody has their own particular flavor
that they add to it. Cory Mittleider: Yeah, that's true. Every
bearing manufacturer, tries to and they do a good job of setting
themselves apart from one another,