Line Tensioner

A device for moving an object comprising:

• a drive cylinder with at least three drive grooves rotating in parallel planes that are perpendicular to a long axis of the drive cylinder;
• a shaft parallel to the drive cylinder upon which at least two idler pulleys rotate;
• wherein the idler pulleys rotate in planes parallel to each other, which planes are at an angle to the parallel planes of the drive grooves, such that, as a line passes around a first drive groove, onto a first idler pulley, and around the first idler pulley, the line, as it comes off the first idler pulley, is aligned with a second drive groove;
• and wherein as the line comes around the second drive groove, onto a second idler pulley, and around the second idler pulley, the line, as it comes off the second idler pulley, is aligned with a third drive groove;
• wherein the line is attached at a first end to an object and a second end is under tension;
• wherein, as the drive cylinder is rotated the object is moved;
• a line tensioner assembly that provides the tension to the second end comprising:
• a stationary cam surface;
• and
• a plurality of line tensioners rotating with the drive cylinder, each having a line gripping portion and a cam follower, wherein the line gripping portion is brought into and out of contact with the line as the cam follower rides along at least a portion of the cam surface, the line gripping portion pressing the line, providing tension, when the line gripping portion is in contact with the line.