This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
輷 combines 車 (vehicle) with 訇, which likely contributes sound. The exact historical development is uncertain.
The left side 車 suggests a vehicle, and the right side 訇 looks complex. Picture a heavy cart rumbling loudly, but remember its standalone meaning is unclear.
For コウ, imagine a cart making a loud 'koh' sound as it rumbles over stones: koh -> コウ.