First let me say that I am not a truck driver. I've turned wrenches on them, but I'm no professional driver. With that said, I was on my way to the nursing home a while back when I came across an empty flatbed tractor trailer backing into a brick plant. As he backed in, his drive axle dropped off of the pavement and began to spin. He rocked back and forth a few minutes until his truck came to a rest with the drive wheels suspended in the air and still completely blocking the road. One of the guys from the plant came out and pointed to his front tandem axle and the driver just threw his hands in the air. The driver was walking around the truck with a puzzled look on his face. I walked up to the guy, and told him that I didn't mean to mind his business, but why wasn't he locking his tandems. He said that he had tried. I asked if I could take a look. I climbed up and locked his tandems for him. He said "Now what?" I told him to back the truck in and began to walk back to my car. I then started hearing rocks sling, so I turned around to look and both back axles were spinning as he backed in with the trailer brakes locked. The trailer was sliding and bouncing, but he cleared the road and I went about my business.