IBM Selectric I/O Manual Of Instruction page 95

Pin Feed Platen
The pin feed platen a Ilows the use of continuous forms. A
pin wheel assembly (Fig. 190) is located Olt each end of the
platen cylinder. A cam in the pin wheel lifts the pins and
causes them to project above the hub of the pin wheel. The
pins project into a slot in the paper clamp which is attached
to the pin wheel. The clamp holds the perforated paper down
over the pins and assures that the paper will be pu lied up as
the platen turns. The pin sheel cam is prevented from turning
by the cam anchor rod (Fig. 190). The anchor rod is mounted
to the cover just to the rear of the platen.
...... Cam Anchor Rod
Paper Clamp
Adjusting Screw
FIGURE 190. Pin Wheel Ass,embly
Figure 191 shows an inside view of the pin wheel assembly.
It should be noted that the cam is held sta·tionary and the pins
turn with the platen around the cam.
When a pin feed platen is used the paper release lever should
be in the forward or released position. This prevents paper
feed interference from the feed rolls.
FIGURE 191. Pin Wheel Assembly
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FABRIC RI BBON
The ribbon mechanism is divided into two separate distinct
mechanisms. They are the ribbon lift mechanism and the rib-
bon feed and reverse mechanism. The ribbon lift mechanism
raises the ribbon to the printing point before the typehead
prints and then lowers it to allow a visible writing line. The
feed and reverse mechanism moves the ribbon laterally past
the printing point to provide an unused portion for the next
typing operation. It also reverses the feeding direction when
the end of the ri bbon is reached.
The ribbon is a 9/16" fabric ribbon enclosed in a disposable
cartridge unit for clean handling. The cartridge unit con-
tains two spools on which the ribbon is wound. The ribbon
is constantly fed from one spool to the other and back again
unti I the ink supply has been depleted. Replacing the ribbon
is a clean, effortless operati on .
Located to the right of the pointer on the carrier assembly is
the ribbon load lever (Fig. 192).
Ribbon Lift
Ribbon Lift Cam
Ribbon Lift
Lever Ribbon Load Lever
FIGURE 192. Ribbon Lift Mechanism
When pushed to the right, the load lever forces the ribbon
lift guide into an extreme lift position for accessibi Iity. The
ribbon load lever is detented to hold the ribbon lift guide in
the high lift position. The cartridge can be removed from the
ribbon feed plate by simply lifting it off. The ribbon can
then be easily removed from the guide without touching the
ribbon.
Installing a new ribbon is just the reverse of the above.
With the ribbon lift guide still in the extreme lift position,
the ribbon can be inserted into the guide and the cartridge
snapped into place all in one motion. Tapered lugs on the
sides of the ribbon feed ratchet cores automatically guide
the ribbon spools into the correct position. Guide lugs at
each side of the feed plate maintain the lateral position of
the cartridge. Retainer springs attached to the guide lugs