IBM Selectric - Page 52

arm reaches its stop screw. To overcome static fri ction,
read the spring scale whi Ie the arm is moving.
6.
in trying to obtain one any less than. 01 a" .
Rotate Selector latches
If a spring scale is not available, the tension may be
obtained in the following manner (Fig. 114). With the
machine hal f-cycled at a negative five lower case
(machines which are locked in upper case use upper
case -5 character) position and the type head removed,
insert a large spring hook around the lower compensator
arm. Pull so that the rotate arm eccentric just clears
the d~mper spring and release it. The tension of the
rotate spring should be enough to completely collapse
the damper spring against the power frame with the
damper spring stop adjusted at the bottom of the spring.
Machine Half Cycled To A
Negative 5 lower Case
Character
Damper Spring Must Be
Completely Collapsed
Stop Set At lowest
Position, Damper
Spring Collapsed
Stop Set At Highest
Position, Damper
Spring Not
Completely
Collapsed
FIGURE 114. Rotate Spring Tension
With the damper spring stop all the way up, the damper
spring should not be
completely collapsed. Check and
adjust the rotate spring to satisfy both conditions.
NOTE:
lower damper spring stop to bottom before proceeding
with sequence. CAUTION - The damper spring method
is
only useable when it is impossible to obtain a spring
scale.
NOTE: The accuracy given to the next seven coarse
al ignment adjustments determines the "band width" (de-
tenting variation) of the rotate system. Each one of these
seven adjustments contributes to the band width in a dif-
ferent manner. Generally, it takes experience in mak-
ing each adjustment to learn how much accuracy is need-
ed to end up with an accumulated band width which is
acceptable. The band width of the rotate system should
never exceed . 020" nor should any extra time be spent
+5
+4
+3
+2
+1
a
a. Form the stop lugs above the positive rotate selector
latches (Fig. 115) so that the latches will reset si-
multaneously (under the latch bail) just as the cycle
clutch check pawl drops into the notch on the check
- ratchet at the rest position.
6-
- - - -- __ ---'-;r--N
- ------.:
FIGURE 115. Rotate Selector latches
NOTE: The adjustment theory under "tilt selector
latches" also pertains to the rotate selector latches.
b. Adjust the negative-5 latch stop screw so that the
negative-5 latch (Fig. 116) wi II reset simultaneously
as
the check pawl drops into the notch on the check
ratchet at the rest position.
Cycle Shaft latched
At Rest Position
Negative latch Bai I
FIGURE
116. Negative 5 latch Stop Screw
-1
The negative-5 latch controls the position of the
negative latch bai I during zero and all positive ro-
tate selections. Changing the latch adjustment
causes
the coarse al ignment of the zero and all posi-
tive rotate selections to change equally with respect
tothe negative selections. No change is felt in the
coarse alignment of the negative rotate selections
when the negative-5latch adjustment is altered be-
cause the latch is out of the system during all nega-
·tive selections (Fig. 117).
-2
-3
-4
-5
Fl GURE 117. . Excessive Negative 5 latch Clearance
2-34