Very much more heavily built than the 10" model, the popular Rockwell Delta 11" underdrive lathe was available with a choice of three different spindle nose fittings: an ordinary thread (21/4" x 8 t.p.i), the much superior American long-nose taper in an L-00 size or (unfortunately for later private owners)  a short-type  "American Taper" with 6 retaining bolts. Two bed lengths were produced giving a capacity of either 25" or 37" between centres.
An underdrive cabinet stand was supplied as standard and fitted with the same type of variable-speed drive as the 10-inch.  Above the variable-speed drive pulleys was an intermediate countershaft from which a double V-belt drove the 13/8" bore headstock spindle at speeds between 45 and 1550 r.p.m. (the two belts must be matched exactly for length or horrible vibrations will be induced). A single lever on the front of the headstock controlled the engagement of backgear and also acted as a spindle lock; this mechanism, designed to be foolproof, offered an interlock to prevent engagement of gears when the spindle was rotating.
Used only for screwcutting, the leadscrew was slotted to provide power sliding and surfacing feeds via the usual worm-and-wheel arrangement inside the apron. However, although the mechanism was conventional, the T-slot was not - it being unique in have a "T" section, designed to prevent the edge of the sliding key from raising a burr along its edge. Feeds were selected by a three-position quadrant lever (neutral being in the middle) and engaged by a separate snap-in-and-out lever that was easily-operated and absolutely certain in operation.
Besides the normal range of centre-lathe accessories, a complete set of production extras: - bed-mounted capstan units, cut-off slides and quick-release collets holders, etc. was also available - as was the option of a flame-hardened bed.
If any reader can supply a clear copy or photograph of the screwcutting chart for this lathe , the writer would be very grateful..