Strap tension sensing and cut off mechanism

In a strap tightening and cut off tool of the type having a housing, a fixed grip coupled to said housing, a movable trigger coupled to said housing for relative movement with respect to said fixed grip;

• a pull bar having a pawl at one end to grip a strap inserted in said tool, said pull bar coupled at its second end to said movable trigger, said movable trigger causing said strap to be further drawn into said tool as said movable trigger is moved towards said fixed grip and permitting said pawl to nonengagingly move with respect to said strap as said movable trigger moves away from said fixed grip;
• a strap tension and cut off mechanism comprising:
• movable block means having a first position relative to said housing and a second position relative to said housing, said second position being closer to said housing than said first position;
• said movable block means engaged by the head of a strap and having a force exerted thereon by said strap head as said strap is drawn into said tool, said force tending to move said movable block means from said first position to said second position;
• blade means for severing the strap adjacent the head thereof;
• control means selectively presettable to any one of a plurality of positions for applying a selected restraining force to said movable block means to prevent said movable block means from moving from said first position to said second position;
• and movable link means coupled to said movable block means and moved in response to the movement of said movable block means from said first position to said second position, said movable link means also coupled to said blade means to operate said blade means to sever the strap when the force applied to said movable block means by the head of the strap is greater than the restraining force applied to said movable block means by said control means permitting said movable block means to move towards said second position thereby causing said movable link to move said blade means and sever the strap.

A strap tightening and cut off tool for tightening a strap about a plurality of objects to be bundled and severing the excess tail portion comprising:

• a housing having a first end and a second end;
• a pull bar having a first end and a second end, said pull bar coupled to said housing and movable with respect thereto;
• drive means coupled to said pull bar second end for moving said pull bar with respect to said housing;
• pawl means capable of gripping a strap when moved in a direction towards said housing second end and nonengagingly moving over a strap when moved in a direction towards said housing first end;
• said pawl means coupled to said pull bar first end;
• stationary block means coupled to said housing first end;
• movable block means within said stationary block means, said movable block means being engaged by the head of a strap to be tightened, the head of the strap applying a force to said movable block means tending to move same towards said housing second end;
• blade means coupled to said movable block means;
• control means selectively presettable to any one of a plurality of positions for applying a restraining force to said movable block means to prevent the movement of said movable block means in response to the force applied by the head of the strap;
• and movable link means coupled to said movable block means and moved in response to the movement of said movable block means, said movable link means also coupled to said blade means to operate said blade means to sever the strap when the force applied to said movable block means by the head of the strap is greater than the restraining force applied to said movable block means and said movable block means is moved.