Index Mechanism (Old Style) - IBM Selectric Manual

5.
Index Link
.005"
FIGURE
153.
Platen Overthrow Stop
Index Selection Cam
a. (240r27toothratchets) Withthe index cam latched
at rest and the selection lever in the double line
space position, adjust the selection cam front to rear
so that the index pawl clears the platen ratchet by
.015" to .050" (Fig. 154).
FIGURE
154.
Index Selection Cam Adjustment
b. Adjustthe selection cam up or down so that the in-
dex pawl is centered on the cam surface with the
selection lever in the single line space position
(Fig. 155).
Paw I CenterE'd
FIGURE
155.
Vertical Adjustment OJ
Index Selection Cam
53
NOTE: On machines equipped with 54 tooth rat-
chets, adjust the index lever to reliably produce a
feed of two, three, or four ratchet teeth when the
index selector lever is placed in the first, second,
or thi rd index position.
INDEX MECHANISM (OLD STYLE)
1 . All operational control ad justments must be correct be-
fore any attempt is made to adjust the index mechanism.
2.
Index Link and Index Link Stud
a. Asa preliminary setting position the index link stud
in the middle of the slot in the pawl carrier. The
setting provides an average leverage ratio for the
pawl carrier. Subsequent adjustments may require
that the position be altered slightly.
b. With the index selection lever in the single line
space position, adjust the index link so that the in-
dex pawl bottoms in the ratchet against a tooth
after. 030" rise on the index cam (Fig. 156). Hal f-
turn ad justments may be made by disconnecting and
turning the link at the top.
The cam rise may be simulated by leaving the cam
latched in the rest position and placing four strips
of IBM card stock between the cam and the cam
follower (Fig. 156).
4 IBM Cards
Cam Latched
At Rest
FIGURE
156.
Index Link Adjustment
c. Adjust the index link stud forward or back in the
slot of the pawl carrier so that one full tooth of
motion is given the index pawl after it starts to
drive the platen (Fig. 157).
NOTE: Adjustment of the index link and link stud
must be considered together. Make these ad just-
ments alternately until both are correct.
The upper index pawl stop must allow the index pawl
to bottom in the ratchet.