That's a good suggestion, Lee. My next step has to be to take a look at
my clamps, and see whether I need to make any adjustments. I didn't think
of the issue you mentioned, and you are absolutely right!

Actually, no he isn't. The length of the clamp handle tip to the pad it
pushes on is always a fixed length. The end of the pipe or the beam goes up
or down on the screw, but it does not affect the clearance to a cross piece
above it.

I would suggest one modification. A bar on a pivot that can be lowered over
the clamps a few inches below where they sit, for when you move the cart.
It seems I always hit a cord or block of wood, the rack stops quickly, and
half of the clamps fall off on my head or toes.
--
Jim in NC