IBM Selectric - Page 49

Carrier Return
Clutch Arm
Actuating Arm Stud
Clutch Actuating Arm
FIGURE 136.
Adjust Clearance For
.015" To .020"
~-=---t- (Horizontal:;
b
Carrier Return Actuating
Arm Adjustment
8. Overbank Ad justment
a. Old Style - With the carrier held fully to the left
against the margin stop, a clearance of .003" to
.008" should exist between the working surfaces of
the escapement pawl and the escapement rack tooth
(Fig. 137). Adjust the left hand margin rack bush-
ing to obtain this condition (Fig. 138).
FIGURE 137. Escapement Pawl Check
The overbank adjustment insures that the escapement
pawl wi II enter the correct escapement rack tooth
when the carrier return clutch is unlatched at the
left margin. The ad justment may be observed from
the top with the platen and deflector removed and
the left margin stop positioned toward the middle
of the rack. The overbank may also be ad justed by
adjusting the margin rack bushing to clear the nylon
washer on the margin rack by .025" to .030" with
the carrier resting at the left margin. The right hand
margin rack eccentric should be loose when making
this adjustment (Fig. 138) so that the left margin
stop will be against the stop latch on the carroier.
The .025" to .030" compensates for the .022" float-
ing action in the escapement pawl. (The correct
adjustment for the margin rack eccentric is covered
under the Margin Control section.)
90
48
b.
Lcc~cr. !v~crg:n Reck Eccentric
FIGURE 138. Overbank Adjustment
NOTE: Any change in overbank on machines
equipped with this old style margin rack assembly
wi II di recti y affect the cl utch unlatchi ng ad justment.
New Style - With the carrie I-rest ing at the left mar-
gin stop, adjust the margin rack overbank guide
(Fig. 139) left or right on the margin rack to obtain
a clearance of .00111 to .005" between the stop
latch on the carrier and the left hand margin stop.
On machines equipped with a floating stop latch,
the floating action of the latch must be removed,
by pull ing the latch to the right with a spring hook,
before this clearance can be observed.
Margin Rack
FIGURE 139. Margin Rack Overbank
Guide Adjustment
The adjustment of the overbank guide on the margin
rack determines the rest position of the margin rack.
The adjustment insures that the left margin stop will
set accurately when the stop is slid to the right
against the margin stop latch on the carrier. In
addition; the adjustment of the overbank guide,
plus the amount of lateral motion that the guide
permits the rack (due to the design of the guide)
when the carrier moves into the left hand margin
during a carrier return operation, automatically
provides the carrier with the overbank required for
proper escapement pawl re-entry at the completion
of a carrier return operation.
Clutch Unlatching - With either style margin rack held
to its extreme left position, the carrier return latch keeper
shou Id clearthe latch by . 005" To .015
11
at the un latch-
ing point (Fig. 140). Check by manual I y holding the
latchattheunlatchingpointwhile the machine is idling.
Lengthen or shorten the carrier return unlatching I ink to
obtain this clearance.