<font color="blue"> a big machine that looked like a street sweeper with a really big hopper to pick them up. </font color>

That sounds a little different than the shakers they use for Cherries. Do I take it the pecans fall to the ground and are swept up? On the cherry shakers, there is a metal frame that goes around the tree and holds a canvas that catches the fruit before it hits the ground. The canvas is tilted and the cherries roll off into containers.

Steve