IBM Selectric Reference Manual

The adjustment of the shift clutch ratchet determines
how much the clutch spring wi II be expanded when the
shift mechanism is at rest. Expanding the spring too
much may cause fai lure of the cam to reach the detent-
ed position, because the spring would be expanded too
soon. Insufficient expansion would allow the clutch
spring to drag when at·rest creating a load on the motor
and on the shift release mechanism.
3. Shift Cam Stop - Adjust the stop so that the shift clutch
ratchet has .010" to .030" rotary motion between the
shift cam stop and the shift release arm with the mech-
anism at rest (Fig. 68).
Shift Release Arm ___ _
Holding Inner Lug
Of Ratchet
FIGURE 68. Shift Cam Stop Adjustment
The adjustment insures that the shift cam will not be al-
lowed to travel past the detented position.
NOTE: The stop should not bind against the spring
clutch when the adjustment is made.
Shift Cam Detented
FIGURE 68.1 Shift Cam Stop Adjustment (Late)
CAUTION: Be sure the cam is detented at the time the
stop adjustment is checked.
2-18
4.
Shift Cam Brake (Fig. 69) - The shift cam brake sha II be
so adjusted, that the shift cam wi II stop in the center of
the detent position ± .015
11
, when the detent roller is
held away from the cam during the shift from upper case
to lower case.
Brake
FIGURE 69. Shift Cam Brake Adjustment
hift Cam
Detented
Excessive braking action could prevent the cam from
reaching the detented position in the lower case. Insuf-
ficient braking action would result in a noisy shift oper-
ation and expose the mechanism to possible parts break-
age.
5. Shift Release - Adjust the shift release link (Fig. 70).
With the shift keylever bottomed, the shift release arm
shall clear the shift clutch ratchet stop by .010" to
.030
11
• A balance between the two releasing points in-
sures the proper adjustment.
Adjusting Link
Figure
70. Shift Release Mechanism
NOTE: The ,shift bellcrank (Fig. 70) attached to the
right end of the bail should be set prior to making the
I ink adjustment. For proper leverage the bell crank
should operate with same over-center travel in both
directions.

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