Machine for automatic stringing or collaring of packages with plastic tape

Claim 1

A tape drive means comprising: a pair of rollers consisting of a first driving roller and a first counterpressure roller for advancing the tape; a second driving roller and a second counterpressure roller for retracting the tape; a seesaw upon which the driving rollers of the two pairs of rollers are mounted, the two counterpressure rollers being fixed, the first driving roller in a first position of the seesaw cooperating with said first counterpressure roller, and the second driving roller in a second position of the seesaw cooperating with said second counterpressure roller; said seesaw being provided with two pivotal frames rotatable about corresponding swivel shafts and connected together by a guiding member and which carry, at a predetermined distance from the corresponding swivel shaft one driving roller each of the roller pairs; two alternatingly energized driving motors having different rates of rotation, the driving motor having the higher rate of rotation used for both advancing the tape and retracting the tape, and the driving motor having the lower rate of rotation being used for generating the final tension in the tape during the final stage of tape retraction; and wherein, when the respective driving roller is in its position of operation, each of the pivotable frames assumes a position such that each of the lines connecting the shafts of the driving rollers with the swivel shafts of the pivotable frames, and each of the lines connecting the shafts of the driving rollers with the shafts of the corresponding counterpressure roller include an acute angle with the line connecting the swivel shaft and the shaft of the corresponding counterpressure roller, whereby the reacting tensile force of the tape engaged by the active pair of rollers tends to rotate the corresponding pivotable frame by togglelever action.