1847    J. O. Halliwell  II  				Span-beam, the great beam..in a barn.
1860     		(new ed.)	 23  				Span beam, the horizontal beam passing over the whim in which the upper pivot of the perpendicular axis moves.
1883    W. S. Gresley  230  				Span-beam, a long wooden beam supporting the head pivot of the drum axle of a gin, and resting at the extremities upon inclined legs.