turn round, revolve, roller
輥 centers on circular motion: turning around, revolving, or a roller that spins. The meanings all share the idea of something rotating or rolling.
輥 combines 車 (vehicle, wheel) with 昆, which likely contributes the sound. The character expresses a wheel turning or a roller.
A vehicle (車) with a component that suggests rolling (昆) makes a roller that turns round and revolves.
For コン, imagine a con artist spinning a roller to turn the wheel of fortune: con -> コン, and the roller revolves.