Originally Posted by darrentoma
You might be right about this design pivoting on 3 axis - in which case the word spherical would be misleading as would the below portion on etrailer's website:
Unique spherical axial bearing allows easy pivoting of hitch head
Smooth, 360-degree movement - not just front-to-back and side-to-side tilting
Built-in cushioning absorbs road shock
If it does in fact involve a 6 directional pivot, perhaps the spherical term (and otherwise) is more of a marketing thing (rather than a direct intent to mislead).
There is literally a spherical bearing in the middle of this design. It sits on a lateral (horizontal, side-to-side) non-rotating shaft; this is the "bearing shaft" in Figure 10 of the Q20 installation manual (CM_16130_INS.PDF
). It may sound good for marketing, but it is technically valid.
Certainly "360-degree movement" is false. The head can't (and should not anyway) rotate more than a small fraction of a turn in the lateral axis (pitching nose up and down), even though the spherical bearing itself would allow unlimited rotation in that axis. The head also can't (and again should not) rotate more than a few degrees in the longitudinal axis (rolling side-to-side), and the spherical bearing would not allow more than that anyway. Any rotation in the vertical axis (yawing as when turning on the road) is undesirable because that's that the pin does, and the extra parts of the design prevent this rotation. I think the "360" terminology was likely a marketing fabrication, because people wouldn't understand a multi-axis pivoting joint. Referring to "not just front-to-back and side-to-side tilting" is taking a disadvantage of the spherical bearing design and implying that it is beneficial, which is classic marketing spin.
I'll give Curt Manufacturing the benefit of the doubt and assume that the "360" references are earnest marketing and sloppy governance, rather than deliberately misleading.
The "road shock" claim is pretty shaky, as the rubber only cushions rotation limits. If you hit a bump in the road, the vertical shocks goes through the hitch metal-on-metal and is not cushioned. That's normal, and I have no problem with it, but I question claiming that the design's "Built-in cushioning absorbs road shock".
Originally Posted by darrentoma
The 'Built-in cushioning' aspect would relate to your comment of this design needing 'additional elements to constrain the head'. When you mention this aspect adds clunking (and potential wear points) - I think you would have to actually test the hitch - there is absolutely no clunking at all in my application - I find it super quiet; as does my friend with the Q16 (probably 7500+ fully loaded vs my 6,000 +/-).
The extra parts to prevent vertical rotation run into rubber bumpers, limiting both the vertical axis rotation and the other axes of intentional movement. In the same Q20 installation manual, Figure 13's diagram to show the right-side grease fitting also shows two heavy steel loops hanging down from the head; they are there to ride against rubber blocks to prevent vertical axis rotation and limit longitudinal axis rotation. Since it's not metal-on-metal sliding or banging the result is quiet, as everyone who has one seems to say.
I understood this design from the diagrams in the installation manual, but it's probably easier to see in person. It took a few minutes looking at one on display at a local RV dealership to be sure that I got how it worked.
Just a side note: anyone planning to use a Reese Sidewinder (which I am certainly not
suggesting) should be aware that is incompatible with the spherical-bearing Curt hitches; apparently the Sidewinder overloads the hitch's vertical rotation stops.
And all of this is only about the head pivoting design; the jaw design is another subject entirely. Interesting, since not so many years ago a recreational 5th wheel hitch was like a commercial hitch, pivoting on the lateral axis only, with bare shaft ends in greased sockets - no side-to-side tilt, no rubber cushioning, no extra parts.