Green’s Dictionary of Slang

1. the ‘falling sickness’, epilepsy.

c.1566		Harman Caveat for Common Cursetours in Viles & Furnivall (1907) 51: Those that do counterfet the Cranke be yong knaues and yonge harlots, that depely dissemble the falling sickness. For the Cranke in their language is the falling euyll.
1592		Groundworke of Conny-catching Ch. 11: This monsterous desembler, a Cranke all about.
1610		Rowlands Martin Mark-all 58: One that counterfeited the falling sickness, they termed him a counterfeit Cranke, for Cranke in their language is the falling sicknesse.
c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions .
1788, 1796		Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn).
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.

2. a mendicant villain who specializes in faking sickness, esp. epilepsy, and who often displays convincingly horrific sores and wounds, created by the application of various herbs.

1622		Beaumont & Fletcher Beggar’s Bush II i: Jarkman, or Patrico, Cranke, or Clapper-dudgeon, / Frater, or Abram-man; I speak to all / That stand in fair election for the title / Of king of beggars.
1707		‘Rum-Mort’s Praise of Her Faithless Maunder’ in Farmer Musa Pedestris (1896) 36: Crank and dommerar thou couldst play, / Or rum-maunder in one day.
1754		Scoundrel’s Dict.

3. (US) a dedicated sports fan.

1889		Nat. Police Gaz. (NY) 7 Dec. 10/1: Where [...] baseball was running wild [...] football ha now got Its grip on the affections of the ‘cranks’.
1933		Bulletin (Sydney) 6 Sept. 40/3: Sam was a wrestling crank. Clean mad on the game, Sam was.
1955		L. Allen Hot Stove League 171: The word ‘fan’ was coined by Ted Sullivan, the legendary manager and scout of the early days, as an abbreviation of fanatic. [...] Before that fans were known as ‘cranks’.