Punched tape 1 passes over tape-transport roll 2 which is mounted on carriage 3. As carriage 3 travels to the right, roll 2 with tape 1 approaches link 4. If link 4 is opposite a hole punched in the tape, then the link remains stationary. As carriage 3 travels to the left, ratchet wheel 5 runs up against pawl 6, mounted on the base, and is turned through an angle corresponding to one tooth. This moves the tape one pitch. Carriage 3 is reciprocated by cylinder cam 7 which is keyed to driving shaft A. Roller 8 of carriage 3 rolls and slides along the groove of earn 7. Spring 9 returns link 4 to its initial position. Pawl 10 and spring 11 prevent unintentional rotation of ratchet wheel 5.
$3357$CR,FD$