Teletype 28 - Page 105

ISS 8, SECTION 573-U8-700TC
3.25 Manual and Power Drive Backspace Mechanism (For Fully Perforated Tape)
ECCENTRIC
POST
(A) BACKSPACE RATCHET
Requirement
-----------Teeth of backspace and feed wheel ratchets
(Top View)
to line up (visual alignment). Feed wheel
ratchet to be in detented position.
To Adjust
With adjusting clamp mount~ screw
friction tight, rotate backspace ratchet to
meet the requirement. Tighten screw.
(B) BACKSPACE PAWL CLEARANCE
(1) Requirement (Preliminary)
With backspace bellcr~ rotated
clockwise, the backspace pawl should
miss the first tooth by a clearance of
,..----------- Min 0.003 inch---Max 0.010 inch
at point of least clearance.
(Front View)
(2) Requirement (Final)
------- The backspace pawl should miss the
first tooth and engage the second tooth
by at least 1/2 of the right engaging
surface of the backspace pawl (as
gauged by eye) when backspace pawl
first contacts the ratchet tooth.
To Adjust
Take up all rotational play of backspace
ratchet in relation to feed ratchet by
rotating it clockwise at same time rotate
I (Front View)
v-I-"?
ft~· - t I
bellcrank clockwise. With mounting screw
friction tight, rotate eccentric post to meet
the requirements. Tighten screw.
'' - ·tf- ()~ gement:
.,, ,','/ -....;:::- Final minimum ~:"second
-:i_~l I_~---~ 1/2 of surfac~t"~Iirst point
--............. ·r ratchet tooth
BACKSPACE
PAWL
of
contact.
Page 105