He was moving too fast for me to get a more detailed shot (I had to run alongside him to shoot this). But the hitch was somewhat like a car hitch, a loop around either the seatpost or the seat creating a hinge that could pivot as he turned corners. But it wasn't sophisticated engineering, just clever, slapdash DIY work.

I saw some kids in a housing project playing with carts like this a few years ago. The plastic part was gone, leaving a sort of seat, and there were several carts attached in tandem. They rode their homemade rollercoaster down a sloping sidewalk, all screaming, at about five miles per hour.

Oh, I forgot to mention, the homemade rollercoaster was sighted in Worcester, Massachusetts.