Hipster jokes at the ready...

[Mr. President]

A what from a what :tongue

a crank is a bent portion of an axle, or shaft, or an arm keyed at right angles to the end of a shaft, by which motion is imparted to or received from it.



Where as a sprocket is a profiled wheel with teeth that meshes with a chain, track or other perforated or indented material. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth.



:tongue