Why is HTAD Class I to Class III Trailer Hitch Adapter Not Recommended for Towing

Question:

I have seen multiple sources that say that with a Class I to Class III trailer hitch adapter one should not tow even lightweight trailers. Why is this? Im an engineer and Im not seeing why the adapter is not as good as a class I drawbar with a ball, which is the suggested method. I havent done any calculations, but the adapter uses as thick a steel as the drawbar, and the adapter has more weld area. Is it all about the change in cross section between the 1.25 bar and the 2inch square section? That would be a big, abrupt, change in stiffness. That creates a large stress concentration factor at the weld, inviting a fatigue failure. Whereas the drawbar doesnt have as big, rapid, stiffness change. Is that it, or am I overthinking it? Thank you. Phil

asked by: Phillip B

Helpful Expert Reply:

The hitch manufacturers and the manufacturers of the adapters tell us that adding an adapter between the receiver and ball mount or the receiver and a hitch mounted accessory not only increases the distance between the load and the receiver, but also introduces another piece to the system which can allow additional bouncing which increases the leverage and shock delivered to the hitch. This could apply more leverage than the hitch or its attachment points to the vehicle are designed to withstand.

An adapter like the # HTAD you mentioned is best suited for a hitch mounted accessory like a bike rack.

The best practice would be to avoid the use of a hitch adapter if at all possible, and use parts that were designed to work together.

Do folks use these for towing? I'm sure they do, but it's not a safe practice and I'd be doing the fine folks I work for and the customers we rely on a disservice if I recommended something possibly unsafe.

expert reply by: Mike L