When lever 5 is turned clockwise about fixed axis A, lever 4 turns counterclockwise and moves pawl 3 which turns ratchet wheel 8. At this, tape a is unwound from reel 1 and wound on reel 2. When tie-rod 6 is shifted upward, pawl 3 is disengaged from wheel 8 and pawl 7 engages ratchet wheel 9. Now when lever 5 is turned clockwise, pawl 7 turns ratchet wheel 9 and the motion of tape a is reversed. Springs 10 and 11 hold the links in contact with one another.
$1852$LR,FD$