Early 11" and 12" Sheldon lathes were, apart from their centre height, almost identical. Both were available with between-centres capacities of 24", 36" and 48" and offered with either a semi (3-speed) or full quick-change screwcutting gearbox able to generate 48 threads and feeds.
Both machines could be supplied either as a "G" Type, with a plain apron, or as a "W" Type with power cross feed; in the latter case the apron was of a much stronger, double-wall construction.
A hardened and ground headstock spindle, of  11/16" bore and 4 Morse Taper, was supplied as standard and ran in bronze bearings but as an option the spindle could be supported on either pre-loaded ball bearings or Timken taper rollers.
Several styles of stand and countershaft were available, including a selection of  "fast-and-loose pulley" types for bench, wall and ceiling mounting  - the most complex of which was a "Double Friction Countershaft" which provided, via a crossed belt and locking clutches, a mechanical reversing system.
By the early 1940s this type of separate drive system was considered irredeemably old-fashioned and a range of compact, underdrive stands were made available, fitted with a choice of two all V-belt countershaft units. The "E" Type had eight hand-switched speeds  whilst the "U" Type offered a quick-change mechanism, controlled by two external levers  which could be moved whilst the lathe was running.  These well-designed drive systems, eventually fitted into more modern-looking stands, remained largely unchanged until production finished..