Collapsing railcar during multi-forklift unloading - video

[awright]

Like jdurand said, except that my analysis would be that any forklift moving ever so slightly FASTER than the others would "drive out from under the load," transferring his load further forward relative to his front wheels. As he began to lose his load it would transfer to the others. Also, as his mast tipped ever so slightly forward his lift vector would push the load out, further disturbing the forces on the other lifts.

Coordinating three (or four? I couldn't see) forklifts with powerful engines to move in exact synchronism would be a challenge. I wonder if this unloading mode had been used successfully in the past.

Note: I have NEVER operated a forklift. Just physics.

[Frank S]

As pretty much all of us have said there were a possibility of a multitude of mitigating factors that could have and would have caused the load to be dropped.
Even the act of tilting back once the stanchions were cleared needed to be carefully executed and done at the slowest possible rate. all it would take in doing that would be 1 guy being a little ambitious while the other were taking their sweet time he would have noticed the rear of his forklift begin to rise then in a panic would have lowered his forks slightly causing the others to have more load then it would have been just what happened a domino effect.
We've unloaded stuff here at my place using 3 lifts 2 on 1 side to do most of the lifting and 1 on the other to counter and over balancing effect when doing it like that though you can't tilt back unless there is enough room for the fork lifts to run under the load. In my case 2 machines were actual forklifts and the 3rd was a backhoe with the loader bucket removed and a carriage & forks installed that time we were picking up a 18,000 lb trailer 2 machines could lift 8K each and the other one only 6k but even with 22K total cap being on sand we had little margin of safety to work with and we didn't have to move the machines just lift high enough for the truck to drive out from under, the next time we made a heavy pick was my pencil sharpener lathe that weighs close to 26k. For that I built my A Frame Gantry which is strong enough to hold the entire lathe but we put 1 8k fork lift on one side and my backhoe on the other. Most of the weight was held by the gantry giving us a great margin of safety for that pick.

[stillldoinit]

In the many years I was in the factory setting doing machine repair and millwright type work I saw many machine movers do magic in some of their moves. One time I picked up a machine with forks at what I thought was a good place to swing so all the CG was low. I needed to sit down and get a better pick. As soon as the weight was released from the fork, the machine tipped back and fell over backward. Made one hell of a boom but fortunely it was shop made machine weldment and was still functional. The only thing damaged was my ego. It was near lunch time and when I got back from lunch, there was a rubber chicken hanging from a noose on the front of the machine. For the next 20 years until I retired, anytime anyone made a mistake, they got the chicken until one day it disappeared. What I learned from me dropping the machine, was always have a piece of wood or cardboard on the fork for friction and have the machine chained to mast. The machine movers always said steel on steel is no deal. Lift and tilt back to get CG closer to the machine and move very slow.

[Frank S]

In the many years I was in the factory setting doing machine repair and millwright type work I saw many machine movers do magic in some of their moves. One time I picked up a machine with forks at what I thought was a good place to swing so all the CG was low. I needed to sit down and get a better pick. As soon as the weight was released from the fork, the machine tipped back and fell over backward. Made one hell of a boom but fortunely it was shop made machine weldment and was still functional. The only thing damaged was my ego. It was near lunch time and when I got back from lunch, there was a rubber chicken hanging from a noose on the front of the machine. For the next 20 years until I retired, anytime anyone made a mistake, they got the chicken until one day it disappeared. What I learned from me dropping the machine, was always have a piece of wood or cardboard on the fork for friction and have the machine chained to mast. The machine movers always said steel on steel is no deal. Lift and tilt back to get CG closer to the machine and move very slow.

A piece of old conveyor belting or a rubber mud flap from a truck is what I have used the most

[MeJasonT]

what they needed was a Peugeot 205 car, I drove my lathe 440lbs from Yorkshire to Cumbria, i figured it was no heavier than two fat adults in the back, although that may have been true the COG was that well thought out. any speed over 50 and the car started to weave like a roller skate. The relationship with my girlfriend was still new and it was her car, ooops. That little car was built like a tank. The lathe was man handled into the car by 4 men at Harrogate show ground and unloaded by two farmer boys in Brampton. Would i do it again, hell yes - NOT.