Ferris Trade and Wheel

This is a Ferris Wheel, but the original trailing centers, when they meet in the middle, Trade with each other before finishing.

\syhlines{b3n,g3n,g4s,b4s} \sxvlines{b3s,b2s,g2n,g1n}
3 1 3 1 4 2 4 2 3 1 2 4 2 4 1 3
before Ferris Trade and Wheel after