• neidu3@sh.itjust.works
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      15 hours ago

      No. The joint isn’t threaded, it’s a slew ring. Think of it like a wide diameter ball bearing (rod bearing? Pin bearing? Not sure about the English word…) with some extra locking mechanisms to hold the top part in place.

      What happened here is most likely a damaged or worn slew ring.

      Source: I helped replace the busted slew ring on a ships crane once.

    • Ferrous@lemmy.ml
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      19 hours ago

      There’s a remote risk of this catastrophic failure happening due to bad maintenance, installation, or building, but there’s no risk of this happening due to normal rotation/swing. In other words, assuming the machine is in good working order and used for realistic applications, this will never happen.

      Here’s a video that explains how excavators achieve infinite swing angle without tangling the hydraulic hoses that go to the motors in the tracks. The dude in the video knows his stuff.

      https://youtu.be/oUVE2PIV5_k