from The Century Dictionary and Cyclopedia
- n. A supplementary coupling between railroad-cars, etc., used for security in case the main coupling should accidentally give way or become unfastened.
- n. A hook or other device attached to the end of a chain for the purpose of connecting it with another chain or of fastening it to any object.
Sorry, no etymologies found.
For pedal-driven fans, a chain-coupling would suffice, such as a bicycle chain.
"Bear the boat off from the boom, and fire at the chain-coupling; that ought to do the business for us."