1889 P. N. Hasluck ii. 14 The bed-plate is..cut away to allow the crank-arm and cross-head to pass.
1911 XVII. 1005/1 In a turning piece, the perpendicular let fall from its connected point upon its axis of rotation is the arm or crank-arm.
1951 25/1 A flexible brush should be used to brush away any dust..at both ends of the crank arms.