the 1800 rpm synchronous motor may need a gear reduction gearbox connected to it to reduce the speed of the input shaft 65 to something more reasonable for example 180 rpm instead of 1800 rpm then small differences in clutch apply release times would have negligible effect on positional accuracy power is transmitted from the input shaft 65 to the clutch assembly 55 via the 90 u00b0 meshing of the input shaft drive gear 90 and clutch drive gear 85 which can be either a worm gear a helical gear or some other gear combination as long as a 90 u00b0 change in power flow is permitted to drive the input side of the clutch assembly 55 the input shaft 65 is supported by bearings 60 which can withstand both radial and axial thrust forces the bearings 60 are retained by suitable bearing caps or restraints which can withstand both axial and radial forces the clutch assembly 55 when deactivated will not transmit rotary motion to the clutch output shaft 105 each clutch assembly 55 must be activated by a timed electric signal which connects the flow of power from the clutch drive gear 85 through the clutch assembly 55 to the clutch output shaft 105 and lead screw 10 or 510 a controller 78 including a central processor unit capable of applying these timed signals can be used with either centralized or distributed logic the controller 78 may operate using either an open loop mode.