Just How Big Are the Biggest Bearings?

I don’t recall a single bearing class where someone didn’t want to know what the largest bearing ever made was. From my stint as a bearing engineer in heavy industry, I gained quite an appreciation these behemoth bearings and the machines that use them. On the engineering side, there really isn’t all that much difference. There are a couple of extra zero’s, but the principles and techniques are fairly transferrable between a 1 inch bearing and a 1 yard bearing.


Chasing down THE largest bearing is tricky…because everyone wants the credit and most of the largest bearings are custom built with only 1 or 2 being built with a couple of replacements. Certainly, we can narrow the field down to some select.

Machinery: Wind turbines, drag lines, continuous miners, mining trucks, tunnel bores and perhaps a little surprisingly, giant Ferris wheels.
We covered a story back in 2007 that is very well in contention from SKF for the Repower Systems 5M Wind Turbine. The 5M’s bearing, with its 1.5-meter inside diameter, weighs 2,700 kg and is the largest of its type ever manufactured by SKF. https://www.powertransmission.com/issues/0207/skf.pdf

Slewing ring bearings are quite an animal that can grow up to 25’ in diameter or more. These are usually assembled on site with the rings shipped upright on a semi. These giant slewing (or turntable) are used under large bases that have to turn; think draglines, steel mill cranes, construction cranes, etc. You can see a 24’ bearing being assembled here: https://www.youtube.com/watch?v=2cA9CuKHg6k. These bearings can easily pass $300k each and insurance companies will usually require that at least one replacement bearing is produced and stored.

There are so many great applications; mining truck wheel end tapered rolling bearings, steel mill multi-row rollneck bearings, crane sheave bearings, the applications are numerous.
What is the largest bearing that you know of? I would interested in finding THE largest bearing ever made.

http://jalopnik.com/5934614/the-ten-biggest-land-vehicles-ever-built