Here is my story. We were doing a trenching job for drain tile. We had done most of the trenching the day before, then had a huge storm which lasted into the next day. Anyway, we were loading the 3 ton trencher onto the trailer connected to our parked Dodge 3500 which was sitting, pointing down the rain soaked hill. Needless to say, as the trencher went up the ramps, the front of the trailer put enough lifting power on the trailer ball that the back of the truck lifted enough to start skidding 8 feet down the hill. One employee jumped into the truck and jumped on brakes and emergency brake. Can't imagine what would have happened. Just remember to get big machines onto the trailers before the truck has time to start moving.