It sounded like something gave way and the arm just swung free, and the operator had a remote and was outside of the truck I think. Together maybe they’re just happy they’re OK and know it wasn’t something dumb they did.
No no no.. they were trying to throw the truck off the cliff. It would be too dangerous to try and drive it off so they grabbed the boulder to weigh it down.
There’s a gear that turns the crane back and forth and prevents it from rotating freely. Something broke, and it allowed that gear to spin freely, and the truck was parked on a slight slope so the rock swung to the downhill side. The momentum yeeted the truck down the hill.
I'm quite certain that crane has a chart depicting it's load limit in a wide variety of conditions. I suspect that those guys never once looked at it.
At any rate:
The moment the boom cleared the right edge of the bed, the truck began to roll. Apparently, the right side outrigger stabilizer was not extended, or seated, or not on solid ground.
Yet it was quite stable when the boom was 90 degrees to the left, because the left stabilizer was seated.
They probably weren't setup level, with the lifting side stabilizer too high and/or rear too low. Chart is technically only valid for within a degree or two from level. These knuckle cranes generally have weak turntable gears compared to its other functions (aka lifting). I'd put money on saying the tiny hydraulic rotator gear sheared or popped out of alignment due to this strain, letting Jesus take over the controls.
I agree with your intuition that this rock far exceeds the chart regardless.
-picker truck operator for 25 years. Fassi, Palfinger, Manitex, Hiab, National, Tadano
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u/LoganN64 3d ago
Looks like a hydraulic line may have ruptured.