I watched it again, looks like the tracks slid a fair bit before he went over. From what I can tell it's a combination of the "operator" trying to unload on an un-level trailer and after the bucket is set onto the groun he trys to steer using the swing (pushing the tracks the other way and sliding off the side). It's hard to see the swing movement when he's on the trailer but you can see it, and when he falls off you can see the counterweight is no longer centered on the tracks.
Looks like it slid a good 3-4 feet before it went off!
I'm guessing a lack of training is at fault as well, most of the time truckers want to unload equipment and watching them do so (even in civilian jobs) can be quite amusing
I watched some guy walk my 385 up along a shoulder, one track up on the pavement one track in the ditch. Pushed the shoulder down a good 2 1/2 feet, then when he tried to turn onto the pavement the track caught under the lift of pavement and was going to rip half the pavement out trying to get up. Sooooo then he tried to swing under the powerlines and got all jammed up with the bucket. I let him play around with it another 10 minutes before I went over an offered my help.
Needless to say they got me to unload it at the other end too haha!
Oh and my big pet peeve with truckers? You have to remove the counterweight of a 385 to move it, so you have to use the machine to load it onto a second trailer. Watching those monkeys scratch the **** out of my paint was the first and last time I ever let them do it. Ever since then -I- will load/unload the damn thing and then if you really want to monkey around trying to track a machine onto a trailer, be my guest.
