crank (n.) Look up crank at
"handle for turning a revolving axis," Old English *cranc, implied in crancstæf "a weaver's instrument," crencestre "female weaver, spinster," from Proto-Germanic base *krank-, and related to crincan "to bend, yield" (see crinkle, cringe). English retains the literal sense of the ancient root, while German and Dutch krank "sick," formerly "weak, small," is from a figurative use. The 1825 supplement to Jamieson's Scottish dictionary has crank "infirm, weak, etc."

The sense of "an eccentric person," especially one who is irrationally fixated, is first recorded 1833, said to be from the crank of a barrel organ, which makes it play the same tune over and over; but more likely a back-formation from cranky (q.v.). Meaning "methamphetamine" attested by 1989.
crank (v.) Look up crank at
1590s, "to zig-zag," from crank (n.). Meaning "to turn a crank" is first attested 1908, with reference to automobile engines. Related: Cranked; cranking.