IBM Selectric Manual page 25

In some cases it may be found that after the eccentri c
stud is adjusted the roller will not drop but remain
trapped at the top of the V-shaped slot. If this oc-
curs, lengthen the rotate I ink and then recheck the
eccentric stud adjustment.
NOTE: The eccentl:c stud should always be kept
in the lower half of its orbit so that it will tend to
turn in the tightening direction as it operates against
the sideframe. Also, if the correct detenting of the
II
Mil
(-5)
cannot
be
easily obtained with the eccen-
tric stud adjustment the preliminary homing adjust-
ment (Adj.
#8)
must be readjusted.
d. Damper spring stop - with the type head removed,
raise the stop so that when a lower case IIM" is half-
cycled the damper spring wi II just collapse against
the sideframe. Check by pull ing the compensator
arm away from the sideframe with a spring hook and
then allow it to go back in slowly (Fig.
64).
Machine Half Cycled
To Negative
5
Lower
Case Character
Damper Spfing ..........
Damper Spri ng Must
Be Completely Collapsed
FIGURE 64. Damper Spring Stop
The main purpose of the eccentric stud adjustment is to
stop the negative motion of the rotate arm as it approaches
the negative five position so that all of the pressure on
the compensator roller wi II be relaxed when the com-
pensating arm has reached its full negative position.
Assuming that no ratio change was felt in the system at
the time of making the eccentric stud ad justment, stopping
the rotate arm early to relax the pressure on the roller
wi II cause the negative motion of the rotate arm between
the negative four and negative five rotate positions to be
reduced, or the detenting ofthe negative five to be posi-
tive with respect to all the other rotate positions.
23
Since the ratio change adjustment will not affect the
negative five position, the type head is then rehomed
to the negative five position making it detent properly
but causing all of the other positions
(-4
through
+5)
to
detent too far negative. The lost motion of the rotate
arm is still felt between the negative four and negative
five rotate positions. The rotate arm motion in this area
can be controlled by the ratio change ad justment whi ch
will be discussed under the next adjustment. This re-
homing of the typehead to the negative five position
(which is usually a slight refinement of the original
homing adjustment) is accomplished by the eccentric
stud adjustment rather than by slipping the rotate shaft
within the rotate pulley. It has been found that the
homing adjustment can readi Iy be refined to the nega-
tive five position with the eccentric stud while at the
same time obtaining a relaxed condition for the com-
pensator roller (accomplished by controlling the length
of the rotate I ink and reseating the compensator roller) .
12.
Ratio Change Adjustment -With the machine hal f-cycled
under power to an upper case
II
R", form the paddle on
the rotate eccentric arm until the uppercase
IIRII
(-3)
detents the same as the upper case
II
Mil
(-5).
Each time
the paddle (Fig. 65) is formed the machine must be re-
cycled under power before observing the detenting of
the
II
R". This allows the eccentri c shoulder to reseat it-
sel f in the compensating arm.
Form This Paddle
FIGURE 65. Ann Assembly In -3 Position
CAUTION: When forming the paddle the V-shaped
wedging slot may accidentally open up causing the roller
to drop. If this occurs, reseot the roller by raising it to
the top and striking a series of "M'sil.
Forming the poddle hw. no effect on the negative five
position. This can be easily seen by looking at Figure
66w\;ich5howslhea,-rn assembly in u negative five posi-