Cont:
On all the lathes above 18 inches in capacity, both spindle bearings were hardened - but on the smaller machines only the front bearing benefited from this treatment. The headstock bearings had their own oil supply, separate from that within the geared headstock, each being fitted with an adjustable sight-feed 'drip' oiler. The spindle end thrust was absorbed by alternate bronze and hardened-steel thrust collars against the rear of the headstock casting.
Power was fed, via large, flat pulleys into a layshaft - so reducing some of the vibration and stresses before the drive was passed to the mainshaft - whilst he main drive pulley on the headstock was given its own (ball) bearing to prevent belt loads beings transmitted into the drive shaft. The internal headstock gears were arranged so that only those required to drive the spindle were in mesh, all the others remaining idle to reduce frictional losses - a system that was widely used on all types of geared-headstock lathe at that time.  The initial drive shaft transmitted its power to a 'driven shaft' with a cone of five gears. Power was then sent to a second 'driven shaft' having a cone of three sliding gears that engaged with three of the cone gears on the first driven shaft. On one end of the three sliding gears a positive stepped clutch was formed and, by sliding these three cone gears along the shaft, they connected with a spring-tensioned cone of two gears with another positive stepped clutch. When in this position the cone of three gears - and the cone of two gears - were clutched together and gave power to the fourth and fifth cone gears on the second driven shaft. By sliding these five gears further along, the fifth cone gear on the second driven shaft was engaged, thus making five changes of speed direct to the spindle - as well as five changes of speed through the back gear - thus providing a total of ten spindle speeds - all selected one lever. A wonderful arrangement, until it went wrong.
Instead of an ordinary thread backed by short register, the spindle nose had a  register both in front and behind - that at the front acting as a pilot to the chuck or face plate whilst the larger diameter was threaded with a wide shoulder ground accurately at right angles to the smaller diameter. To help customers, the various spindle diameters and threads were standardised on the 16", 18" and 20" lathes - as were those of the 24" and 30" models - thus allowing chucks and face plates to be (economically) interchangeable between the models in each group.
More on the early days of Greaves, Klusman Company can be found here:

Greaves-Klusman lathe with the headstock spindle removed to show the arrangement of the three shafts, the drive gears and the associated selector mechanism.

The Greaves-Klusman lathe had the option of this neatly arranged and very compact drive system - though the lack of a jockey pulley to increase the "wrap-around" of the wide flat belt around the motor pulley would have been the limiting factor in the lathe's ability to remove metal.