The ball-bearing races in the Cataract headstock were "pre loaded"; this idea can be better understood by referring to the illustration below: Figure 1 shows the Duplex Double-Row Bearings before being correctly set, the clearance between the inner rings at point '"B" having been calculated by the bearing manufacturer to produce a pre-determined initial load suitable for bench lathe purposes.
When the bearings have been pressed into the headstock casting they can be set to the correct pre-load by turning the locking  nut shown at "A", in the lower illustration, until the inner races meet.

Section through a late-model, completely enclosed, twin V belt driven Cataract headstock , showing the location of the pre-load setting screw A.
The bearings were lubricated through wick-feeds from cups on the back of the headstock. The bearings were sealed with cork rings and the ball separators made from Bakelite.
A mechanical brake, actuated by an external lever  marked "FORWARD - STOP - REVERSE, was located inside the headstock, with its band and friction lining arranged around the spindle. The Friction material was not riveted to the band, but free to move within it and so distribute wear as evenly as possible. 
Depending upon the drive unit selected, either six or eight speeds were available from 230 to a maximum of 1500, 2000, 2500 or 3900 rpm depending upon the particular model.
Although the model illustrated used two V belts to drive the spindle, some versions were fitted with three. No backgear was fitted.