POWERED CORD REELING DEVICE WITH AUTOMATIC CORD TENSION-CONTROLLED DISENGAGEMENT AND TYPEWRITER CARRIAGE RETURN MECHANISM USING SAME

摘要

The cord reeling device (18) includes a cord tension sensing mechanism (112, 114, 106) for detecting the increase tension of cord (80) when a driven load, such as the paper carriage of a typewriter, ceases to move and the drive mechanism continues to operate. It is desirable to disengage the drive mechanism at that point rather than to cause frictional wear or overloading of the motor pending a predetermined amount of driving time prior to disengagement. Upon the cord tension reaching a preset value, a clutch pawl (82) will disengage a drive clutch (70) and prevent further wear of the clutching arrangement. To prevent premature disengagement of clutch (70), a shock unloading pretensioned spring (39) is incorporated in the drive unit (24) to absorb the initial shocks and forces experienced during acceleration of the load driven by cord (80).