If this device is what I think, I may have seen one or two. The appartaus
I saw a few years ago in effet extended the trailer tongue, so that the
pivot point was very close to the rear axle of the tow vehicle. The
standard hitch mechanism was held in line with some bars which resembled an
equalizing hitch.
Stick with me here, and I'll tell you why this seems to be a good idea. It
has been stated by others that a two axle trailer tends to understeer.
Now, if that trailer starts to swing out of line with the tow vehicle, it
would push slightly sideways on the hitch, and since that is on the rear of
the truck, well behind the axle and center of mass. This could (at least
in theory) cause the truck to move in the same direction that the rear of
the trailer went. Worst case outcome: jackknife. Now, imagine
stretching the tongue of the trailer, and put the reciever at the rear
axle. The trailer now has quite a bit less leverage to push the tow
vehicle around, so it should be more stable. It might also be possible to
have a higher tongue weight for the same reason. Basically, the closer you
can get things to the center of mass of the tow vehicle, the better off you
are. Anyway, that's my take on it, but this could be an entirely
different animal. Hope I didn't confuse anybody.
Calvin K
Trailer physics 101
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