IBM Selectric Maintenance Manual page 73

automatically provides the carrier with the overbank
required for proper escapement pawl re-entry at the
completion of a carrier return operation.
5.
Clutch Unlatching - With either style margin rack held
to its extreme left position, the carrier return latch keep-
er should clear the latch by .005" to .015" at the un-
latching point (Fig. 148). Check by manually holding
the latch at the unlatching point whi Ie the machine is
idling. Lengthen or shorten the carrier return unlatching
I ink to obtain this clearance.
NOTE: Should the clutch fail to properly latch (on
machines equipped with the early margin rack) after the
clutch unlatching adjustment has been completed, check
the margin rack eccentric adjustment which is located
in the Margin Control section. The eccentric may be
holding the rack too far to the left restricting the mar-
gin rack motion thereby reducing the amount of bite
that the latch may take on the keeper.
Margin Rack
Held To The
Left
---..
Latch Held Even
With The Keeper
Corner
FIGURE 148. Clutch Unlatching Adjustment
6; Torque Limiter - The torque limiter should transmit 1 to
2
pounds pull on the carrier as the carrier is unlatching
the cl utch at the left margi n.
If a spring scale is available, the adjustment may be
checked by holding against the carrier with the push end
of the scale and allowing the carrier to slowly unlatch
the clutch at the left margin.
If no scale is available, the torque may be estimated by
holding the carrier while the clutch is engaged. The
torque limiter should slip readily yet return the carrier
positively without any hesitation when the carrier is re-
leased.
The adjustment is made by adjusting the eccentric stud
in the torque limiter hub. If sufficient adjustment is not
available at the eccentric, the torque limiter spring may
be shifted on the torque limiter hub by positioning the
torque limiter spring clamp.
NOTE: The carrier return clutch arbor should have an
end play of .004" to .006" between the torque limiter
hub and the C-clip on the operational shaft. Adjust the
play by positioning the .torque limiter hub laterally on
the shaft. The end play can be adjusted easily if the
torque limiter spring is moved to the right, off the torque
limiter hub.
7. Carrier Return Interlock Contact -
a. Form the N/C support so that the O/P lifts the N/C
contact .002" to .005" (Fig. 149).
b. Form the N/O support so that the O/P clears the
N/O contact .035" to .045" (Fig. 149).
N/C Contact
.002" to .005"
(§)
Rise
O/p
N/O Support
FIGURE 149. Carrier Return Interlock Inactive
c. With the carrier return clutch latched, position the
mounting bracket so that the N/O contact rises .010"
to .020" from the N/O support (Fig. 150).
NOTE: The N/O contacts must remain closed during
return of the carrier to the left margin.
Excessive rise on the contact straps will cause the con-
tacts to bounce.
Mtg. Bracket
o
.010" to .020"
~73I<§:;;;:J,
Rise
N/O Contact
q)
FIGURE 150. Carrier Return Interlock Active
CARRIER RETURN - HIGH SPEED
NOTE: Adjustments 1 through 3 are the same as CARRIER
RETURN - LATE STYLE. Be sure that the print escapement
and operational control adjustments are correcf before attempt-
ing the carrier return adjustments.
4. Overbank Adjustment
a. Adjust the left hand margin rack bushing to obtain
a clearance of .002" to .004" between the working
surface of the escapement pawl, and the escapement
rack tooth with the carrier held to the left in an over-
bank condition (Fig. 150.1) •
2-45.2