One of the most important accessories for a watchmaker's lathe is the drive system. A properly designed and built unit can transform the lathe, making it possible to select exactly the right speed for the spindle - as well as being able to drive various milling and grinding accessories held on the bed.
The Leinen unit below is a good example of modern practice, the one-piece supporting base for the lathe being made from from cast-iron and standing on three rubber feet. The motor supplied was of either a 3-phase 0.12 kW precision-balanced  unit which drove through a belt change to give speeds of 1000, 2400 and 5300 rpm - or a 1-phase a.c 0.07 kW unit with variable speed drive to 2800 rpm which gave, in conjunction with belt changes, a speed range from 300 to 7500 rpm. The motor speed was changed by the handle fastened to the right-hand motor end plate.
An extension shaft above the motor provided a means of taking the drive to a countershaft which powered milling, drilling and grinding attachments held in the compound slide rest.

Drive Unit No. 155 for WW Lathes.
This neat assembly was built on a cast-iron base with a swivel-mounted flange holding the motor and countershaft. The motor was available to exactly the same specifications as that fitted to the No. 154 Unit shown above

Drive Motor No. 156 for WW Lathes. A beautifully presented, rubber-foot repulsion induction motor for 1-phase. 0.08 kW with speeds to 2800 rpm infinitely variable in both directions by operation of the black-knob topped lever. The motor was available in a variety of specifications and voltages.