Quote:
Originally Posted by gburlison
So just to make sure I understand your point.
Assume the trailer has a tongue weight of 5 pounds.
Build a two wheel drive bot with a third wheel opposite the trailer....
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Not just two-wheel drive, but two-wheeled, if you like.
I don't see it so much about tongue weight as about the torque that the clevis (or whatever's pinning the hitch) will sustain.
Imagine a robot. Put a pair of wheels on it and hitch a trailer to it. Move some robot weight as far forward of the wheels as necessary to get the trailer hitch to lock up (there's a barrel pinned into C-channel, and you're trying to rotate it the "wrong" way). Now if you move more weight forward it's not just the tongue weight of the trailer pressing down on your hitch, but rather the weight of the trailer -- like you're actually trying to lift the trailer. I haven't built a trailer, but from kicking across some regolith I might estimate it at 20 lb. At max, you could actually have the whole robot+trailer weight balanced on your two wheels, as long as that pin and C-channel hold.
On the PRO side:
Ironically, by trying to flex the hitch in the "wrong" direction and making it harder to flex in the "right" direction, you might make some maneuvering easier.
You've increased F_n (and everything downstream of it) by ~12%
CON:
Minimal resistance to spinning the whole assembly -- you've both taken load off of the trailer's wheels and eliminated the degree of freedom intended in the hitch.
I don't really think it's worth doing, but I think it's well worth reminding ourselves that mg and F_n are not always synonymous.