There is a known infrequent failure mode for tilting bed trucks that cause the bed to tilt up without the operators knowledge. It is not difficult to find examples. The force reaction for a hinge behind the rear axle will always make the front end lift. How far can be calculated from your statics and dynamics textbook.
[ul]
[li]
From the pictures and the video, it doesn't look like a dump truck; it looks similar to a POD mover truck, which has four columns that can be raised up about 5 ft higher than the top of the POD. The picture posted by Spartan5 shows at least two similar columns.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
Those posts appear to be part of the bridge. A pod-mover is highly specialized and it is extremely unlikely that a scrap dealer will have any use for one.
Roll-offs are common as are straight dumps and semi dumps.
Bill
-------------------- Ohm's law
Not just a good idea; It's the LAW!
It's odd, because there's nothing that looks like a dump bed, which should be behind the remnants of the walkway, and the columns don't look like they belong to the walkway
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
Those are sign supports similar to the ones on the other side of the highway.
I have been looking in vain for a picture of the part that actually hit the bridge.
If it was rails for a drop bin, they may have been peeled all the way back and be on the ground under the debris.
Bill
-------------------- Ohm's law
Not just a good idea; It's the LAW!
I expect the truck had the empty roll-on frame raised.
You can see the back of the frame with the big roller in the second post in this thread and there is no box behind it so it doesn't appear the truck had a box on it.
Judging from this picture, you are exactly correct, Lionel.
He probably dropped the bin and pushed the control to lower the rails(sub frame).
For some reason the rails didn't lower all the way, and he never looked back.
By the way, the truck has at least four rear view mirrors, maybe five.
Bill
-------------------- Ohm's law
Not just a good idea; It's the LAW!
Frank must have gotten the subframe at exactly the right angle to maximize damage and momentum transfer to the walkway. Most videos I've seen of such collisions resulted in subframe just sliding up the obstacle.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
Hi IR; Most dump trucks have a single acting hydraulic lift system and may easily ride up.
The roll off trucks have a double acting hydraulic system and something fairly bog, has to break before they ride up.
In this case I think Frank hit both effects.
By the way the truck reared up, he may have had the angle just right.
The angle notwithstanding, it looks as if something big broke and the subframe then peeled back.
Bill
-------------------- Ohm's law
Not just a good idea; It's the LAW!
