IBM Selectric Manual

6.
NOTE: The eccentric may require a readjustment if
the rest poshion of the pivot pin is changed during car-
rier return adjustments.
Escapement Cam - Adjust the cam by rotating it on the
fi Iter shaft so that the cam follower roller just reaches
the low point of the cam at the rest position (Fig. 100).
The cam is accessible from the top by inserting the Bristol
wrench between the carrier return and backspace key-
levers just in front of the margin rack.
Check the adjustment by holding the cycle clutch check
pawl out of the way so that the cyc Ie shaft can be rotated
backward. Rotate the filter shaft gear backward slightly
and observe that the escapement tri p link moves forward
immediately. This wi II insure that the escapement cam
is
not resting past the low point. To insure that the cam
follower has fully reached the low point, hand-cycle a
print operation. The escapement trip I ink should not
move during the first part of the cycle.
The cam ad justment affects the tim ing of the print escape-
ment. Advanced timing could cause the trip to occur
before the print action, resulting in crowding or blurring
of the printed characters. Retarded timing wi II cause
the cam follower to rest part of the way up the incl ine
of the cam. This could restrict the escapement trigger
from resetting over the torque bar lug as the filter shaft
returns to its rest position. The spacebar mechanism
would then be disabled.
Onmachinesequipped with the old style spacebar lock-
out mechanism, the lockout cam adjustment must be
checked each time the escapement cam adjustment is
changed. Advancing or retarding the escapement cam
could allow the lockout cam to disable the spacebar
mechanism.
CAUTION: On machines equipped with the old style
spacebar lockout mechanism, a lateral position of the
escapement cam on the fi Iter shaft must be maintained.
When the machine is at rest the lateral position of the
escapementcamshouldallow .050
11
to .060
11
left to right
movement of the spacebar lockout cam.
7.
8.
9.
Escapement Trip Link
Escapement Trip Link - Adjust the trip link so that a
clearance of .007
11
to .010
11
exists between the torque
bar I ug and the hook of the escapement trigger in the
rest position (Fig. 100).
The adjustment insures that the torque bar wi" always be
rotated far enough to trip the pawls from their racks.
If excessive clearance is present, the escapement may
eventually fail as wear occurs in the system and reduces
the amount of travel given to the trigger.
Insufficient clearance may prevent the trigger from re-
settingoverthe torque bar lug at the end of each cycle.
It may also cause the escapement trip to occur too early
in the cycle. The trip should not occur before the print
action.
CAUTION: In adjusting the escapement trip link be
sure
that the trigger lever stop (if present) and the ad-
justable screw in the spacebar latch lever do not restrict
the upward travel of the trigger lever.
Escapement Trigger Action - Adjust the trigger guide
{earl y style machines} or the trigger knock-off eccentric
stud (new style mach ines) so that the escapement trigger
will become diSengaged from the torque bar lug when
the escapement pawl clears the rack by .010
11
to .015
11
(Fig. 101).
Trigger Lever Upstop (long carriage.machines) - With
the machine at rest and a clearance of .007
11
to .010
11
existing between the trigger and the lug on the torque
bar, adjust the trigger lever upstop so that it has a clear--
anceof .001 11 to .005
11
with the trigger lever (Fig. 102).
The trigger upstop prevents the trigger lever from bouncing
as it returns to its rest position.
Cam Follower Just Resting At Low Point
FIGURE 100. Escapement Cam And Link Adjustment
37

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