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Print Cam Detent
Armature----------.,.:~
Print
Magnet
Figure 2-2. Printing Mechanism
return the linkage to its normal position. The res-
toration of the print clutch latch is described under
Print Cam Mechanism.
Print Cam Mechanism
The print cam mechanism is not a self-contained
. unit which can be removed as an assembly. The
components operate in separately removable sup-
port and guide bars. The function of each print cam
is to cam its associated print wheel toward the
platen.
The mechanism for a single print position is
shown in its latched-up position (Figure 2-4), with
the print clutch latch resting on the armature knock-
off lever. When the knockoff lever pivots clockwise,
the print clutch latch is moved into the cut-out in the
knockoff lever by the latch compression spring
(Figure 2-3).
As the latch releases the tip of the print cam
dog, the dog spring pulls the dog into a flute of the
continuously running print clutch shaft.
The dog
starts driving the print cam, and after the cam has
2.2
Print Wheel Hanger
f'rint Wheel
turned approximately 3/ 4 of a revolution, the high
lobe drives the print wheel hanger toward the
platen (Figure 2-6).
The print clutch latch is relatched on the tip of
the armature knockoff lever by the restore lever
which follows the print cam (Figure 2-5). This
places the latch in the path of the print cam dog,
and disengages it from the print clutch shaft flute .
Print cam motion stops, and the cam is held by the
inter-action of the detent and the print clutch dog
spring tension.
Print Wheel Unit
Each print wheel has 48 characters around its periph-
ery and is driven continuously by the 48 tooth print
wheel drive gear. The print wheel pivots on a hub
which is part of the print wheel hanger.
When the print cam cams the print wheel hanger
toward the platen, the hanger pivots at the top against
hanger spring tension (Figure 2-6). The print wheel
is not cammed all the way against the platen, but mo-
mentum continues the motion and a character prints.
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