This is a connection to a tow bar f

[gondola993]

This is a connection to a tow bar for towing a car behind a motorhome. I don't have any additional pics. Here's the bar: Link. This is all the information I have. How would you say the forces contributing to this failure occurred: Axially, vertically, or laterally (hard turn left or right), etc. I guess I'm asking, can you read the pattern of the break on the spherical end to tell me anything about what caused the break? Thanks.

 

[Compositepro]

This is what I would expect from jackknifing the trailer. The easiest way to to that without much drama is while backing up.

 

[metengr]

Hard to say from this one photograph but it looks like the failure was from overload under shear forces.

 

[EdStainless]

With better photos we could at least tell which direction force was being applied.

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P.E. Metallurgy, Plymouth Tube

 

[gondola993]

Thanks everyone. Sorry I don't have any more info or pics to share. I use the same bar and was hoping to learn how to avoid whatever caused this failure. My friend has a different style bar and he recently had a failure. This failure I know was caused by a high vertical load because the receiver inserted into the towing vehicle bent downward 0.5". What I don't know is if there were any cracks developing in the T6 aluminum prior to the complete fracture. Any thoughts?

You can get a magnified image over here:Link

 

[Ron]

Is this item welded? The lower photo shows a linear failure that looks like it might be a weld. There is also a crack evident on the drilled face on the left.

What alloy of aluminum is used? You mentioned T6 which is the temper, but not the allow.

I would question the use of aluminum in this application because of the fatigue potential.....yes, I know that aluminum is used for airframes and other fatigue applications; however, those items are fabricated under stringent criteria....I doubt that is true of a hitch manufacturer.

 

[gondola993]

No idea what aluminum is used; if it helps I believe it's cast and advertised as aircraft grade. The bar is of this design: Link. The first joint pivots about the x-axis, the second about the z, and the third about the y.

 

[Ron]

I agree with CompositePro....looks like jacknifing would cause this. Dynamic tensile failure on the right side.

 

[gondola993]

Thanks everyone!