Forum Discussion
Endricken
Apr 18, 2015Explorer
The Lever and Breaker bar analogies are fine if the components are movable, however typically the Adapter/Pinbox/Frame are all "fixed/pinned" solidly, so only forces greater than the strength of any of these would cause rotation. For example, if a lug nut was welded to anything, a torch or saw would be needed to remove it vs. any normal breaker bar.
Hence my earlier problem of the horizontal Kingpin plate being slightly bent up along the rear where it was least reinforced after encountering unusually great forces/stress on two separate towing occasions reflects some bending / rotation of this part only of the Pinbox. NO Frame problems were evident when the Pinbox was removed and replaced with the Goosebox. Nor were ANY evident until after the pothole collision and presumably failure crack occurred that got slowly worse with additional towing duration and stresses.
The broken frame was cracked along the same Wing mounting side as the Pothole shock occurred and was bent STRAIGHT up - reflecting a direct Vertical stress, not twisted as one might expect if rotational forces were present (Unless the box beam was so rigid to prevent this).
Hence my earlier problem of the horizontal Kingpin plate being slightly bent up along the rear where it was least reinforced after encountering unusually great forces/stress on two separate towing occasions reflects some bending / rotation of this part only of the Pinbox. NO Frame problems were evident when the Pinbox was removed and replaced with the Goosebox. Nor were ANY evident until after the pothole collision and presumably failure crack occurred that got slowly worse with additional towing duration and stresses.
The broken frame was cracked along the same Wing mounting side as the Pothole shock occurred and was bent STRAIGHT up - reflecting a direct Vertical stress, not twisted as one might expect if rotational forces were present (Unless the box beam was so rigid to prevent this).
About Fifth Wheel Group
19,006 PostsLatest Activity: Jan 13, 2025