The two countershaft units in the base of the stand provided separate drives to the spindle and headstock backgears.  The drive from the variable speed unit passed to the right-hand unit and from there, via a dog clutch, either across to the left-hand unit (and up to the end of the spindle) or up to the lower of the two V-belt pulleys on the headstock - and hence into the backgear assembly.

The Rivett 1020S drive unit was cushion mounted, within the cabinet base, and formed a complete system which could be maintained through large openings in the end and the back of the bed - or withdrawn completely through the end door.
The electric motor carried an expanding and contracting pulley arrangement, the opening and closing of which was activated by a smaller motor controlled by push buttons, marked Fast and Slow, positioned to the right of the screwcutting gearbox. The drive then passed to a shaft carrying a dog-clutch arrangement which allowed the motion to continue either to its end - and so drive a triple V belt connected to the backgear assembly in the headstock - or to be passed across to a parallel countershaft which directed the drive straight to the end of the headstock spindle.