RoyJ wrote:
valhalla360 wrote:
A monster truck camper with 1000-1500lb 6-8ft behind the axle gets rocking, it can put drastically more bending force on the frame.
It may visually appear that way, but the EC 1165 does NOT put thousands of pounds that far back from the axle.
Google its COG: 61.5", or roughly 5' measured from the front of the bed. That puts it right on, or a hair behind the rear axle.
Let's say it's 6" behind the rear axle: 6000 lbs x 6" = 36,000 in-lbs of moment. Assuming the typical hitch ball is 4' from rear axle, 36k in-lb/48" = 750lbs.
So the bending stress of a EC1165 is the same as 750 lbs of hitch weight. Who'd worry about that on a modern dually?
Empty & built to theoretical design standards sitting stationary...true.
Truck campers are notorious for being overweight by a significant amount and no guarantee the extra weight was evenly distributed.
Also, there are some substantial storage compartments all the way at the back. If he loaded it stern heavy, it could easily be an extra 500lb 6ft behind the axle (3000ft-lb).
Then you have the center of gravity well above the axle and frame. The forces on the ball when braking are generally at frame level. So when you brake hard, the force is in line with the frame putting it into compression not bending (0ft-lb). A truck camper with a COG a couple feet above the frame develops a moment arm. Under hard braking...6500lb * 2ft = 13,000ft-lb.
Realistically, probably multiple factors. Going down a smooth straight road at a steady speed, likely no problem grossly overloaded. Slam on the brakes just before hitting a big tope while overloaded with a frame that has had some holes punched in it for tie downs...the overloading may be an issue.
That's the problem with load ratings. The engineers generally assume a worst case scenario and people get away with overloading because actually experiencing that worst case is rare...but when you hit that worst case, the poo hits the fan.
We'll probably never see it but I would still like to see the actual weights and what the frame looks like at the failure. I'm betting with that info, it becomes obvious what happened.
