The procedure for offloading a grain truck includes pulling into the elevator, opening the dump gate and hydraulically lifting the bed until empty. It also requires lowering the bed before driving away. The last step is critical, as illustrated here.

Unfortunately this particular driver forgot to lower the dump trailer before driving out of the stall and as a result the bed broke the dump valves for the overhead bin. The bin was full of wheat and the rest is a very messy history. (Thanks for the tip John!)

(Photo credit Steven Tucker, whose truck was the next in line behind this mess)