First offered during the 1970s, the large and powerful TOS SU100 and SU125 lathes shared a bed of identical dimensions - 800 mm wide and 630 mm deep - but with centre heights of, respectively, 1050 and 1250 mm. Distances between centres available for both include 2000, 3000, 4000, 5000, 6000 and 8000 mm - though the real between-centres capacity on both was some 215 mm shorter. The lathes were able to take a workpiece between centres weighing up to 5 metric tons, or 6 metric tons with the use of a fixed steady.
Other than the previously-mentioned differences in capacity, the two lathes were of an identical mechanical specification with the same headstock, 105 mm spindle bore, 54 longitudinal rates of carriage feed from 0.08 to 7 mm per minute and 54 in traverse at 33% of the longitudinal rate. Rapids on both directions of feed were an option, a separate 1.1 kW, 2800 r.p.m. motor being provided that gave rates of 3600 mm/min longitudinally and 1200 mm/min in traverse.
Screwcutting was arranged to provide 27 metric pitches from 1.125 to 56 mm by gearing that meshed directly with the bed-mounted rack, and 27 metric pitches from 0.66 to 112 mm by using the 65 mm diameter by 12 mm pitch leadscrew. 42 English pitches could be generated from 28 to 0.25 t.p.i. and 32 module from 0.5 to 28.
Driven by a 25 kW motor and incorporating a combined, hydraulically-operated brake/clutch unit, the spindle speeds offered as standard ran from 2.24 to 450 r.p.m on the SU100 and from 1.8 to 355 r.p.m on the SU125. As an extra-cost option, both faster and slower ranges could be specified.
The shortest bed SU100 weighed 7600 kg and the equivalent SU125 7900 kg while the heaviest of both - the 8000 mm between-centres models, ran to 11600 and 11900 kg respectively.
The full specification - and details of the various options - can be found below.