Believed to have been founded in 1904 - with production finally ceasing during early 1964 - the lathes made by the American Sidney Company are, compared to the likes of South Bend, Monarch and Hendey, relatively uncommon. However, always very well constructed, they are considered by experienced machinists to be the equivalent of - or even better - than those by other high-class makers such as Monarch (built in the same town), Lodge & Shipley and American Pacemaker.
By the 1940s, all Sidney lathes were massive, squat-looking and especially powerful machines built to withstand very hard work. They were offered in two distinct versions: one with eight and later twelve spindle speeds with ordinary spur-gears in their headstocks - and a very heavy-duty type, with a choice of 16 or 32-speeds, fitted with very smooth-running and quiet double-chevron* (herringbone) gears. As herringbone gears cannot be slid into mesh, these ran in constant engagement with speed changes by dogs with internal and external gears sliding on splined shafts and being moved by the headstock controls so that they locked into the faces of the main drive gears.
From the early 1940s onwards, the twelve-speed lathes were described as "Sliding Spur Tooth Geared Head Lathes" and listed in seven sizes, the model designations being expressed in inches as: 14", 16", 18", 20", 25", 32" and 36". However, this was not a single type, but three distinct designs each intended for their expected duties: the 14" and 16" were, in effect the same, with both taking 30 inches between centres and with three spindle-speed controls levers mounted on a "frosted" rectangular plate on the front face of the headstock. The 18" and 20" accepted 48 inches between centres, the headstock having a large, centrally-placed, 4-position quadrant speed-control lever that hung downwards with two smaller levers, one to the left and the other to the left but above. The standard 24", 30" and 36" models had a capacity of 48 inches between centres, their headstocks being of massive construction with the three speed-control levers all of the quadrant type and arranged in a line across the headstock's front face. All versions could be had with longer beds in intervals of 24 inches.
The 16-speed with herringbone gears in the headstock - often listed with the 32"  in sales literature as "Heavy Duty" - was available as the models 14", 16", 18", 20", 25" and 32". 32-speed models were available as the 14", 16", 18" and 20". In addition, two toolroom versions were listed: a 16-speed and 32-speed with models names of 14", 16", 18" and 20".
By 1958 the range had been slimmed down a little to the Type 16 - a very model very similar to those of the previous decade - offered as two Models, the 2717 (previously known as the 25") and the 3419 (previously the 32"). Also listed were General Purpose Model 16 lathes, described as being: - Heavy Duty Engine, Tool Room and Gap Lathes in three versions, the 14", 16" and 20". All had herringbone-type, 16-speed headstocks with a 3-bearing Timken-supported spindle. An interesting alternative was a newly-developed lathe, the "Model 32 Dial-Master", this retaining the herringbone headstock with 32 speeds engaged by sliding dogs, but with selection using a rotary dial and shifting by a hydraulic mechanism, this activated by a lever once the operator had dialled in the required speed. Two models were offered; the 2013 with a 21-inch swing over the bed and 30 inches between centres and the 2516, the latter with a swing of 25.5 inches and taking 48 inches between centres. Another late-model Sidney lathe, made from the late 1950s until the early 1960s, was the 1307, this version also being sold as a South Bend. The lathe was fitted a 3-phase motor driving a DC generator that supplied the lathe's DC drive motor through a Louis Allis Select-a-Spede Drive.Full details of these later lathes can be found here.
Continued below:

Continued:
Interestingly, in every case and seemingly from at least the early 1920s, the actual swing of a Sidney lathe was 2.5 inches greater than its "Model Type" i.e a Model 24" would have had a real swing of 26.5 inches over the bed (a centre height of 13.25"). Most Sidney lathes from 1940 carried a build plate giving the date of manufacture, the size - expressed as the swing - and often a Government contract number. If the plate is missing, some measurements will be necessary together with reference to the various catalogs shown on this and other pages.
As advanced machines, built to a standard rather than down to a price, Sidney lathes were expensive and the total made of all types very low in comparison to other makers - the "herringbone" versions being particularly rare. Unfortunately, full details of the numbers made is not available, the surviving records beginning in 1930 with Serial Number 5532, this possibly indicating, if they ran in a true series, of only 5432 lathes constructed over a span of 25 years (it's possible that numbers would have started at 101, or even 1001). By 1940 serial numbers had reached  6318, a total production for the decade of only 786. However, by 1946 - obviously contributed to by war-time demand - a further 2,000 examples had been built with serial numbers reaching 8388. With the war over, production once more resumed its more leisurely pace, another 1,991 machines being manufactured before records finish in 1962 at serial 10269 - a yearly average of around 118.
Considered to be overbuilt compared to their size designations - no great disadvantage in an industrial lathe - all Sidney lathes from the late 1930s enjoyed an advanced specification with useful details including, on some, the option of bedways lined with strips of replaceable tool steel. This latter fitting is easy to identify for, when compared to the silvery-grey of the ordinary beds - made from cast chilled iron - they have a bright, chrome-like appearance.
Other feature on many (but not all) Sidney lathes included a massive bed in a "semi-steel" cast iron with four longitudinal walls braced, every 12 or 24 inches, with cross girths; every gear and shaft throughout the machine heat treated and hardened; headstocks with a spindle machined from an alloy-steel forging and running in high-precision Timken roller bearing that took both radial and thrust loads; spindles with a central support bearing; headstock oil filtered and pressure pumped with various distribution methods over the years including one where a tubular manifold in cast iron was set above the gears with holes that directed lubricant over each gear set - a sight glass being provided to check that oil was flowing; a twin-disc combined clutch and brake unit incorporated in the drive from the motor; oil from a sump in the apron pumped around its interior and also directed, automatically, to the bed and cross and top slide ways; cross-feed and top-slide nuts with adjustment to eliminate backlash; a saddle with underneath keeper plates at the front and rear; anti-friction bearings supporting not only all the shafts in the headstock, but also the changewheel gearing, screwcutting and feeds' gearbox, apron, leadscrew, power-feeds' drive rod and the tailstock, cross-slide and top-slide feed screws - the latter pair also provided with ball races to take thrust in both directions.
One owner reports that his 25-inch Sidney was "... incredibly massive with a slowest speed of 9 r.p.m. and, with 30 h.p., a mind-bending 17,507 lbs/ft of torque on hand.... though more importantly, it was a machine built to actually handle that kind of power..."
One surviving earlier model includes an 8-speed, 30-inch type admitting nearly twenty feet between centres with a bed having three supports between the headstock and tailstock plinths. Weighing in excess of 22,000 lbs - nearly 10 tons - the speed range was necessarily slow at 8 to 330 r.p.m..
*Ever wondered why a "double chevron" badge is used on Ciroen cars? It's the result - so claimed - of the company founder, Andre Citroen visiting Poland and seeing large, double-chevron gears in wood driving large machines. The smooth running of the gear form allowed what should have been an unsuitable material to perform well beyond its normal limits. Having bought the patents - believed to be Russian in origin - he took them back to France and began (with the help of  American machine-tool expertise) to make them in steel - one of the first uses being in the back axle of his cars and trucks.