Show notes
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.
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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,