Mechanical unit to selectively drive one of at least two shafts from only one driving shaft, preferably for moving the ink ribbon of a printer.

摘要

1. A mechanical device for selectively driving at least two driven shafts, from a single drive shaft, comprising : - a drive shaft (1) driving a driving wheel (2), - a satellite wheel (3) permanently driven by said driving wheel (2) and loosely mounted on a support (4) which is freely rotatable about the axis of the driving wheel (2), - a first driven wheel (5), rigidly affixed to the first driven shaft (6) for rotation therewith and with which the satellite wheel (3) can come into engagement, - a second driven wheel (7) rigidly affixed to the second driven shaft (8) for rotation therewith, and with which the satellite wheel (3) can come into engagement, - the axes of the driving wheel (2), of the satellite wheel (3) and of the two driven wheels (5, 7) being parallel, and said two driven shafts (6, 8) being disposed at equal distance from the drive shaft (1), said distance being less than the sum of the diameter of the satellite wheel (3) and of the radius of the driving wheel (2) and of the driven wheel (5, 7), characterized by the fact that : - the drive shaft (1) is disposed so as to be substantially in alignment with the two driven shafts (6, 8), - the two driven wheels (5, 7) are adapted to be elastically deformable locally in a radial direction, - and the distance between each driven shaft (6, 8) and the drive shaft (1) being less than the sum of the diameter of the satellite wheel (3) and of the radius of the driving wheel (1) and of the driven wheel (5, 7) by a value corresponding to the amount of possible radial deformation of each of the two said driven wheels (5, 7), whereby, when one of the two driven shafts is jammed, the satellite wheel bears on the corresponding driven wheel, causes elastic radial deformation thereof and, by rolling over its circumference, succeeds in escaping from contact therewith, thereby allowing the support of this satellite wheel to move angularly until the satellite wheel is engaged with the other driven wheel to rotate it and thus to drive the other driven shaft, the whole of this procedure then being repeatable when said other driven shaft is itself jammed.