Simonet Drive Unit and Accessories The DC-102/DZ-450 drive unit incorporates a two speed oil-bath gearbox with output ratios of 1:1 or 6:1. The drive motor is supplied as either a single speed device of 1500 or 3000 rpm or a two speed unit with 1500 or 3000 rpm output selected through a commutating and reversing switch. The drive unit also carries the overhead drive for the milling and grinding attachments. This ingenious unit is self tightening under spring tension.  The milling attachment, which will fit both the DC-102 and the DZ-450, is very similar to the early Schaublin item illustrated elsewhere in this archive. The milling head employs W12 collets and also has a speed reduction gearbox.   Height adjustable grinding attachment. The spindle, running in taper roller bearings, accepts B8 collets and has a maximum speed of 20,000 rpm.