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PB 200 Lift Frame Failure - Industry Warning

PostPosted: 27 Jun 2010, 13:17
by Canadianbombar
We had a total failure of the lift frame on one of our PB 200's this spring (a 99) just behind the pivot point. Entire frame split in half. I initially figured it was a half asleep rookie op backing over the damn thing but then I determind that it had been growing for some time from the bottom up...not the top down due to some rust in the split. I was then thinking maybe the rookie was doing the ole blade/tiller pivot point crash bang but he swore up and down no. Believe it or not, the metal used to build the frame box at that point is incredibly thin for it's intended purpose...somewhere around 1/8th of an inch. Regardless, if I was to take my rookies word he did nothing out of the ordinary..what caused the failure? It stumped me for a while what the problem was other than poor construction specs showing with age as it was the first instance of something like that which I had ever seen on any cat. I finally came to the conclusion that the standard PB 200 can't handle steep approach and departure angles with the tiller down such as terrain park features and tube park walls due to this weak point. This cat did a lot of work in our tube and terrain park. It looked to me that there was a heck of a lot of upward force on the tiller when grooming thru quick transition up and down angles that the lift frame ram did not allow any give for even in up pressure, I would have to lift the tiller the equivelent of 2 or 3 feet to actually get it off the snow at the worst part of a feature angle. As a rusult, I concluded the point on the lift frame that failed would be taking around 8000 lbs of upward force at that point as it was essentially lifting the back of the cat. I think years and years of this may have caused metal fatigue to hairline crack to the failure. Anyone else seen this? Thoughts?