IBM Selectric

/
the -3 character. This allows the eccentric shoulder to
reseat itself in the compensating arm.
CAUTION: When forming the paddle the V-shaped
wedging slot may
accidentally open up causing the roller
to drop. If this occurs, reseat the roller by raising it to
the top and striking a series of -5 characters. This adjust-
ment should require only slight forming of the paddle.
FIGURE 84. Arm Assembly in -5 Position
Forming
the paddle has no effect on the negative five po-
siti on. This can easi Iy be seen by looking at Figure 84
which shows the arm assembly in a negative five position.
+5 +4
+3
+2
+1
0
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In this position there is a clearance between the pad-
dle and the barrel on the rotate arm; therefore any
change in the paddle position just increases or decreases
this
clearance without affecting the negative five posi-
tion of the rotate
arm.
The paddle adjustment does affect all ofthe rotate posi-
tions from a negative three to a positive five position
equally because it controls how long the compensating
arm will rotate about
the eccentric shoulder on the rotate
eccentric arm as it travels from the negative five position
towards
the negative three position. In other words, the
more clearance there is between the rotate arm and the
paddle, the farther the compensating arm can travel und-
er a ratio change condition as it moves towards the neg-
ative three position.
Figure
85i Ilustrates how the detenting pattern of the
type head
is affected by the ratio cI,a'1ge adjustment.
Notlce in Figure 85A that all the rotate positions from
the -3 to the +5 detent equally but much less negative
than the
-5. This indicates that there is too much ratio
change (too much motion) in
the system between the -5
and the -3. The paddle shou Id be formed in unti I the -3
detents the same as the -5.
/
Figure 85B illustrates the detenting pattern of a system
that lacks a sufficient amount of ratio change. All the
rotate positions from -3 to +5 detent alike but too far
negative with respect to
the -5. The system lacks motion
between
the -5 and the -3; therefore the paddle should be
formed out to increase
the amount of ratio change. Note
that the negative four position is detenting the same as
the -3 in Figure 85B. This is because the ratio change is
Paddle leaves the:---l
barrel at this point
+5 +4 +3 +2 +1 0 -1 -2 -3 -4 -5
/ \ /) / \ / \ /) I' /) I \ / ,':\,:.:<.,:.:
/ ' , / \ / '\ / /\ / \ / " / , I '\ / IA i<::':;'/::,
1\ /\ 1\ 1\ /\ /\ 1\ "A /\ .. :.~;::.:::.:: ... ~.:/ ...
/ L _\ / L _, / L...l, I L """"\ / L"""\ / L --\ / L _, / L """"\ / V~'\:;:?::.>\.:
I 'v V V 'v V V V '" :,c .....
·:·~:···.'i:.; . ..;.·.<·:·.\
B. Insufficient ratio change ----------- __ .. ..:.;.:.:,.:: ___
.. ~ .:. ~." "": : .
2-25