Trailers are typically attached to tractors by a "fifth wheel, " in which a coupling pin on the trailer fits into the center of a large horseshoe-shaped piece of metal.
"It is possible that with an old, not properly maintained fifthwheel that the device can get loose, the sides can wear away, the hole that the pin fits into is no longer snug and rigid, " Scott said.
Button's disappointing season continued when he failed to finish in the points after being sent out from his final pit stop with a loose front wheel, having been fifth at one stage.