What is the origin of "journal" to mean a mechanical shaft?

What is the origin of "journal" to mean a mechanical shaft? A more common modern use is in "journal bearing" which refers to the sliding surface between a rotating shaft and a hole it passes through and supports it relative to some other component.

OED 1, 10, says

in Machinery. The part of a shaft or axle which rests on the bearings. (Sometimes erroneously identified with ‘bearing’.)
  Originally used in a more restricted application: ‘It was proposed by Buchanan, in his Treatise on Millwork, to apply the word gudgeon only to the bearing part at the end of a shaft or axle, which is exposed to bending action alone, and not twisting action; and journal to an intermediate bearing part through which a twisting moment is or may be exerted; but the custom of using the word “journal” in both senses indiscriminately is so prevalent, that it is impracticable to carry out Buchanan’s suggestion’. (Rankine Machinery & Millwork (1869) III.iii. § 460.) [Journal or journey in this sense seems to have arisen in the Scotch workshops. No explanation of its origin has been found.] (my emphasis)

I'm going to guess that it originally designated the part which moves → travels → ‘journeys’ in contact with the bearing; but I have no evidence at all for that derivation.