Unlike many other lathes by TOS, where the model number reflected the swing, in the case of the SUS63 and SUS80 this was not the case, the two lathes having, respectively, swings over the bed of 650 mm and 840 mm.
Although of the same design and mechanical construction, the two lathes had different, beds (unhardened as standard) that on the smaller SUS6 being 580 mm wide and 819 deep mm while that on the SUS90 was wider at 710 mm but shallower at 765 mm. As with many lathes of the same design, but different capacities, the larger machine was not intended to take heaver jobs, but to accommodate ones of a larger diameter - the maximum load of 6000 kg able to be carried between centres at their minimum spindle speeds being the same for both.
Other than the previously-mentioned differences in capacity, the two lathes were of identical specification and with the same choice of between-centres capacities of 1250, 3000, 2750, 3500, 5000, 6500 and 8000 mm. The headstock held a 80 mm bore spindle with a metric 100 taper, the reducing sleeve having a 1:20 outside taper and bored to take a standard No. 5 Morse centre - the spindle nose being a type CSN 20/1010 (though a more handy and much quicker to change Camlock 8 nose fitting was an option) .
22 spindle speeds from 9 to 1120 r.p.m. were provided on the SUS63 - and the same number from 7.1 to 900 on the SUS80. Power came from a 18 kW motor that drove by V-belts to a gearbox that incorporated hydraulically-controlled, duplex electromagnetic clutch/brake unit and from there to the headstock's internal gearing. As an option, both lower and higher speed ranges were available, the former using a two-speed 11/16 kW motor that gave 25 speeds from 4.4 to 1120 r.p.m. on the SUS63 and 3.55 to 900 r.p.m. on the SUS80. Higher speeds required a more powerful 22 kW single-speed motor, this providing 12.5 to 1600 r.p.m. on the SUS63 and 10 to 1250 r.p.m. on the SUS80.
On both lathes, over the full spindle speed range, the longitudinal carriage feed rate varied from 0.049 to 3 mm/rev and, when in backgear running at slower speeds, from 0.780 to 48 mm/rev. Cross feed rates were set at exactly half those longitudinal.
Rapids, driven by a separate motor built into the apron, were not provided as standard but could be fitted at extra cost.
Screwcutting, by a 65 mm diameter by 12 mm pitch leadscrew, gave 48 metric pitches from 0.5 to 224 mm, 48 Whitworth pitches from 0.25 to 56 t.p.i., 37 module from 0.25 to 56 and 48 Diametral from DP 0.5 to 112 and Circular pitch threads from CP 1/64 to 31/2.
Equipped with a large No. 6 Morse taper, the tailstock spindle was 130 mm in diameter with a travel of 275 mm on the SU63 and 255 mm on the SU80
The shortest bed SU63 weighed approximately 5200 kg, the equivalent SU80 5700 kg.
By comparison, the two longest lathes in each model weighed 9000 an 10300 kg.
For customers who wanted a large and very strong lathe - but with no need for screwcutting - the makers offered two "production" versions, the SSS-63 and SSS-90. In addition to the removal of the large screwcutting and gearbox and its replacement by a much simpler unit feeds-only box, both lathes had more power motors and higher spindle speeds.
The full specification of the two lathes - and details of the various options and wide accessory range - can be found below..