IBM Selectric - Page 58

7.
Tab Rack
Adjust Tab Rack
•
Bushing (Not Shown) ,~ - . -
Tab Lever
\
~_ _-- - .005" To .020"
- Tab Pawl
(C~o_
~
FIGURE 167. Tab Rack Adjustment
The tab rack adjustment sets up a condition whereby the
escapement pawl will be released into the escapement
rackattheright time to safely engage the correct tooth.
If the tab rack were too far to the left, the tab lever
would contact the set tab stop sooner and release the es-
capement pawl into the rack earlier than it should. The
pawl
could enter the wrong escapement rack tooth and
stop the carrierone space to the left of the desired stop-
ping point. The carrier could stop one space too far to
the right if the tab rack were adjusted too far to the
right.
NOTE: The head of the tab rack bushing should clear
the tab rack plate by about 3/32" when the adjustment
has been completed. This approximate clearance insures
that the tab rack is not ad j usted one fu II space too far to
the left or right.
Tab Interlock - With the carrier return clutch latched,
the escapement torque bar should rotate the tab latch
away from the tab lever pawl by .005" to .025" (Fig.
168). Form the lug on the tab latch that extends down
behind the escapement torque bar.
Tab Lever
.005" To .025" lr
"..- "
/ \
/~n)
/' "IJ/
/'" --
Form Rear Lug Of
tch For Clearance
Escapement Torque
FIGURE 168. Tab Interlock Adjustment
The lug on the tab latch may be formed by using the push
end of the large spring hook as a T -bender.
The adjustment insures that the carrier return and tab
cannot both be latched simultaneously. If both were al-
lowed to latch, the tab lever pawl would lock against a
set
tab stop during the carrier return operation.
8.
1.
57
Carrier Return/T ab Interlock - Form the bottom lug of
the interlock (Fig. 169) to obtain the following condi-
tions:
FIGURE 169. Carriage Return/Tab Interlock
a. With the carrier return mechanism latched, the
interlock should actuate the carrier return latch
keeper forward just far enough to release the latch
when the tab keylever is fully depressed.
b. With the carrier return mechanism at rest, full de-
pression of the tab keylever should not cause the
carrier return latch keeper to move-away from the
latch.
MARGIN RELEASE MECHANISM
Margin Rack Overbank Guide - With the carrier resting
at the left hand -margin, adjust th'! overbank guide (Fig.
170) left or right on the margin rack to obtain .001" to
.005" clearance between the margin stop andthemargin
stop latch on the carrier when the margin rack is in its
rest position
(Fig. 170). When observing this clearance
remove the floating action of the margin stop latch by
pulling the stop latch to the right with a spring hook.
The adjustment insures that the left margin stop will set
accurately when the stop is slid to the right against the
margin stop latch on the carrier.
NOTE: Machines equipped with an old style margin
rack use an eccentric plate mounted on th~ right end of
the margin rack to control the rest position of the rack.
Use the same procedure indicated above to obtain the
.001
11
to .005
11
clearance between the margin stop and
the stop latch on the carri er .