the invention shown herein the unidirectional electric motor is connected to a reversible clutch assembly 38 which is used to reverse direction of rotation of wheel 26 the passage 16 which leads the strap to the drive mechanism is formed by guides 39 and 40 the strap passageway 41 in the drive mechanism 18 is formed by guide block 43 in the nip assembly 28 and drive wheel 26 the drive wheel 26 includes a pair of flanges 44 only one of which is showing which act as guides and prevent excessive lateral movement of strap 6 the ang1e formed by the centers of the feed nip 30 drive wheel 26 and tension nip 32 is in excess of one hundred degrees and for the preferred embodiment is approximately one hundred and twenty degrees the feed wheel surface has been coated with urethane rubber or any other suitable elastomer compound so as to provide optimum frictional engagement between the polypropylene strap and drive wheel 26 the friction engagement is further optimized by the one hundred and twenty degree region of contact between the drive wheel and the strap this enables a drive mechanism having a sing1e movable tension nip to achieve high tension a front guide assembly 48 passes the strap from the drive assembly 18 to the grip and seal mechanism 22 the front guide 48 is pivotally mounted to the nip assembly 28 so that it has the same pivot point as feed nip 30 this permits the guide to maintain proper alignment with nip assembly 28 of drive assembly 18 as may be seen in fig4 7 front guide.