5th wheel help

Be sure you are not lifting the trailer too much with the landing gear. If you put the landing gear down too far, it lifts the kingpin in the hitch. This causes the wider part at the bottom of the kingpin to put upward pressure on the jaws, jamming them. When unhooking, use the landing gear to take up some of the weight, but when you drive out from under the trailer the truck should still raise up 1/4 to 1/2". Same principle as when hooking up, the truck should squat just a little as you back under the trailer. That's why there are ramps on the back of the 5th wheel plate and front of the pinbox.