A few years ago there was a fellow taking his Oliver 77 home from a tractor show near my house. Where the road goes down a steep hill (fortunetly straight) I heard a crash. When I got there the guy was standing in the road surveying the mess. The tractor had rolled forward off the trailer, hit the pickup and broke the hitch (bumper) off. The Oliver was stratling the trailer tongue which was about 50 ft. behind the truck. He had driven the tractor onto the trailer, left it in gear and engaged the brake pedal locks. He then ran one 1 1/2" nylon tie down strap from one side of the trailer, over the tractor's hood to the other side of the trailer. He couldn't figure out how this could have had happened !!!