When slide 1 with ratchet wheel 2 travels to the left in fixed guides k-k, blade 3 remains stationary in the position shown until pin d of wheel 2 leaves the heel of blade 3. Then blade 3 is forced upward by spring 4 a distance less than the diameter of pin d. Further upward motion is restricted by the collar on the stem of blade 3. When, before this, pin a leaves blade 3, upward motion of the blade with counterclockwise rotation of wheel 2 is prevented by pawl 6, pivoted on slide 1 and engaging the teeth on wheel 2. When slide 1 travels to the right, pin d runs up against surface g of blade 3 turning wheel 2 together with disk 5 (only a part of the disk is shown) clockwise until pin b pushes blade 3 downward to its lower position and pins d and b slide along the blade. Since pins a, d, b and e are located at angles of 90°, disk 5 is indexed 90° to each full stroke, back and forth, of slide 1. Pawl 6 prevents counterclockwise rotation of disk 5.
$2783$RG,FD$