Patent ID: 7082872

Claim:
An apparatus for applying tension to a strap in a strapping machine, the apparatus comprising: a. a first driving wheel and a second wheel, each of said first driving wheel and said second wheel having an axis of rotation, said axes of rotation of said first driving wheel and said second wheel being substantially parallel, said axis of rotation of at least one of said first driving wheel and said second wheel having a first position and a second position with respect to said axis of rotation of the other of said first driving wheel and said second wheel; b. said first driving wheel and said second wheel defining a selectable first strap path when said axis of rotation of said at least one of said first driving wheel and said second wheel is in said first position; c. said first driving wheel and said second wheel defining a selectable second strap path when said axis of rotation of said at least one of said first driving wheel and said second wheel is in said second position; d. said first driving wheel having a periphery, said periphery of said first driving wheel defining a first strap-engaging surface, said first driving wheel being adapted to rotate; e. said first strap path being configured such that when said first strap path is selected said first strap-engaging surface does not operatively engage the strap; f. said second strap path being configured such that when said second strap path is selected the strap is wrapped partially around said periphery of said first driving wheel, said second strap path being further configured such that when a sufficient initial tension is applied to the strap, said initial tension causes the strap to apply a sufficient force to said first strap-engaging surface to cause a frictional engagement between said first strap-engaging surface and the strap, said rotation of said first driving wheel when said first strap-engaging surface is in frictional engagement with the strap tensioning the strap; g. said second strap path being configured so that the strap does not move in both a feed direction and a take-up direction at the same time during tensioning of the strap.