IBM Selectric Manual

I
tion. In this position there is a large clearance between
the paddle 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.
/~--~
(~)
FIGURE 66. Arm Assembly in -5 Position
The paddle adjustment does affect all of the 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
+5
+4
+3
+2
+1
0
,,').
I).
/l'-
~
fA
I)..
l.~
I.' \
I'L~
'I. ~
IL~
I
ILl
I'L -\
I -
I \
I \
I
\
I \ I
\
\ I \ I
\
I
I
'
\ I
\
I
\ '
"
\I
V ',;
.;
more clearance there is between the rotate arm and the
paddle, the farther the compensating can travel under a
ratio change condition as it moves towards the negative
three position.
Figure 67 illustrates how the detenting pattern of the
typehead is affected by the ratio change adjustment.
Notice in Figure 67A 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 (toomuch motion) in the system between the "M"
(-5) and'the "RII (-3). The paddle should be formed in
unti
I the II RII detents the same as the II Mil .
Figure 67B
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 II M II (-5) and the II R" (-3) therefore the pad-
dle should be formed out to increase the amount of ratio
change. Note that the negative four position is detent-
ing the same as the "R" in Figure 67B. This is because
the ratio change is not occurring at the negative four
position, thus the arm assembly is operating as one solid
arm at this position.
In Figure 67C the conect amount of ratio change is in
the system. All positions from the -3 to the +5 detent
the same as the -5, Note that when the II R" detents the
sameasthe "M
II
, the detenting of the ,-4 is slightly dif-
ferent. This is caused by the ratio change. No attempt
should be made to control the detenting of the -4 posi-
tion because its position may vary on each machine de-
pending on the amount of latio change required (of each
machine) to make the" R" detent the same as the II Mil .
IIRII
II Mil
A. Too much ratio change
.: .. '
"M"
+5 +4 +3 +2 +1 0 -1 -2 -3 -4 -5
I \ / / I \ I I \ / I \ / \ ' .. :".:'::~"
f\ 1\ 1\ A " A /\ "A /\ .:~. :< ......... , ... .
I L \ I ) \ /! ~ I /, I )\ I '\ I ) \ II 1\ I IA ' .. ' .... ' .. : .....•. ' ............ .
I -\ / L. -\, \ / L -\ I L \ I L -\ I L -\ L -\ I V'~ .... .- ,'.
I
.. , \/ V V V V I ;, .. " .
Y '1 v·.·.::
B. Insufficient ratio change --------------. .. _
.. ~
"R" II Mil
+5 +4 +3 +2 +1 0 -1 -2 -3 -4 .-5
12\ ,2~ I~\ 12\ Ir:~ I~~ I~~. /~\ !\ I.I\.; .. ::~.::::.: ... :~;; .. :.·~.: ..... ·::: .. ".)~.·· •. ::.
I "\ / \ I \ I \ I \ / \ I \ I \ / :'i3:;;< ::->;,
I \ / \ I 'I \ / \ / \ I \ I \ 1/.:"" .\:'.' ' .. ;'.
/ 'V V V \I c. V V V )\<\.:<.',:~: ... ,:,:
Correct ratio change ~~/·<:'·,i·.,·;:.~~
FIGURE 67. Ratio Change Adjustment i::;i)V5}:
24

IBM Selectric Specifications

General

Type	Electric typewriter
Introduced	1961
Keyboard Layout	QWERTY
Carriage Return	Electric
Manufacturer	IBM
Printing Technology	Typeball (golf ball)
Power Source	AC Power
Power Supply	120V AC