IBM Selectric Reference Manual

5.
with the rotate-two latch when checking the left
side. The handle of the Hooverometer must be as
nearly vertical as possible during the checks. The
base
ofthe handle does not reach the center I ine of
the platen when the handle is vertical, but the dif-
ference in height has been compensated for in the
locaf'ion of the scribe line.
b. Platen Front to Rear - With the head of the Hoover-
ometer set at the #2 scribe line, the tool should
just span
the distance between the platen and the
print shaft as illustrated in Fig. 135. Adjust the
platen adjusting eccentrics to obtain this condition
(Fig. 133).
FIGURE 135. Front to Rear Platen Adjustment
Check at both ends of the platen. In order to adjust
the platen adjusting eccentrics it is also .necessary
to loosen the front screws in the eccentric retaining
plates. (Be sure that the Hooverometerdoesnotrest
on the print shaft keyway.)
NOTE: After the correct vertical and horizontal
positions ofthe platen are obtained with the Hoover-
ometer, the vertical position may be refined to pro-
vide even printing between the tops and bottoms of
the characters. Check at both ends of the writing
line.
CAUTION: Any change in the front to rear posi-
tion ofthe platen necessitates a readjustment of the
velocity control plate and anvil. Also, any change
in the platen position may alter the paper feed ad-
justments. All paper feed adjustments should be
checked and readjusted if necessary.
Carrier Shoe Adjustment
a. Carrier Shoe (Early) - Adjust the upper carrier
shoe eccentric mounting st·ud t·o provide .001
11
to
FIGURE 136. Carrier Shoe - Early
2-43
.004
11
verti cal motion of the carrier at the rear
(Fig. 136). Check at several points along the writin~l
line.
This amount of play insures free lateral movement
of the carrier yet restricts the vertical movement to
hel p prevent variation in. the vertical 01 ignment of
the type.
NOTE: The eccentric is accessible with the 3
11
screwdriver through the opening in the escapement
bracket just above the tab torque bar. The si de of
the screwdriver blade should be used if possible.
b. Carrier Shoe (Late) - Adjust the upper carrier
shoe eccentric mounting 'stud to provide .002" to
.006
11
vertical motion of the carrier at the rear
(Fig. 137) when the spring load on the upper shoe
is suppressed.
FIGURE 137. Carrier Shoe - Late
NOTE: The vertical motion may be felt by firmly
moving
the carrier up and down at the rear, so as
to overcome the effects of the spring load on the
upper shoe.
6. Velocity Control Plate - The velocity control plate must
be adjusted to satisfy the following two conditions.
a. With the cam follower held lightly against the low
po i nt
of the pri nt cam, the center of the home char-
acter should clear the platen by .260" to .270".
b. With the cam follower held lightly against the high
point of the print cam, the home character should
clear the platen by .020" to .030".
The copy control lever should be forward for both ad-
justments. These adjustments should be made with the
carrier positioned in the center of the writing line. On
long carriage machines the adjustments should be made
with the carrier at the extreme left hand position.
The print cam has a fixed amount of rise from its low
point to its high point. For this reason, the print cam
follower always receives the same amount of powered
travel or motion from the print cam. However, the amount
of powered travel that the rocker and typehead receive,
from the print cam follower, is directly dependent upon
the position ofthe velocity control plate pi,n the the fork-
ed slot of the follower (Fig. 138). Moving the pin to the
front of the slot decreases the powered trove I of the type-
head as shown by dimension A (Fig. 138). Moving it to

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