Cycle Clutch Operation - IBM Selectric I/O Manual Of Instruction

center position. As the follower arm moves in and out of the
low dwell, the actuating arm moves to the right and back to
its center or rest position.
NOTE: The actuating arm operates only during the
move-
ment of the shift cam.
Shift Contact Assemblies
The contact assembli es operat·ed by the actuating arm are
feedback and transmitting contacts.
The assemblies nearest the front are the feedback contacts.
The assembly to the rear is the transmitting contacts (Fig.
76) •
•
Transmitting Contacts
.J..-_--
Tab
Actuator Arm
Shift Contact Assembly
Shifting to upper case, the inner set of feedback and trans-
mitting contacts are operated by the actuating arm. Shifting
to lower case, the outer set of feedback and transmitting con-
tacts are operated by the actuating arm.
Shi ft Mode Contacts
The shift mode contacts are located just above the feedback
and transmitting contact assemblies (Fig. 73). These con-
tacts indicate whether the printer is in upper or lower case.
This is accomplished by the shift arm tab (Fig. 73). This tab
is bolted to the rear of the shift arm, and moves left to right
with the shift arm. The mode contacts are positioned so that
the tab wi II always hold one of the contacts transferred de-
pending upon whether the printer is in upper or lower case.
C-7 Contact Assembly (835 Printer)
This assembly consists of N/O and N/C contacts and a cam
which is mounted to the shift ratchet (Fig. 76.1).
~1§iii~~~5~~~S;
Cam Follower
Cam
FIGURE 76.1 C-7 Contact Assembly (835 Printer)
I
When the ratchet is released the cam turns with the ratchet.
They both turn 180
0
on each sh ift operation. The cam follow-
er rides on the C-7 cam causing transfer of the contacts.
28
CYCLE CLUTCH OPERATION
The cycle operation occurs each time a character prints.
Everything concerned with printing a character on the paper
is powered by the cycle shaft either directly or indirectly.
The cycle shaft extends from the center of the machine out
through the left side frame. The left end of the shaft is sup-
ported by a self-aligning bearing. The right end fits into
the cycle clutch pulley hub in the center of the machine.
A sleeve inside the hub acts as a bearing for the cycle shaft.
The cycle clutch pulley is in continuous rotation whenever
the motor is running, but the cycle shaft operates only dur-
ing a print operation. A spring clutch called the cycle
clutch spring (Fig. 77) is the driving connection between the
hub on the cycle clutch pulley and a hub on the cycle shaft.
The cycle clutch spring provides a means of engaging and
disengaging the cycle shaft from the cycle clutch pulley.
Cycle Shaft
Latch Pusher Cam
Cycle Clutch Spring
Cy.CI.
Hub On Cy. CI. Pulley
FIGURE 77. Cycle Clutch - Exploded View
The left end of the cycle clutch spring fits around the hub on
the cycle shaft and is clamped to this hub by the cycle clutch
collar. The tip of the spring is turned up so as to fit into a
slot in the collar. This arrangement prevents any slippage at
the left end of the spring clutch and makes it possible to ad-
just the position of the spring in relation to the shaft.
The right end of the cycle clutch spring encircles a hub on
the cycle clutch pulley (Fig. 77). (The hub on the cycle
clutch pulley functions the same as the shift clutch arbor on
the shift mechanism.) The inside diameter of the cycle clutch
spring is slightly less than the diameter of the hub on the
cycle clutch pulley so that the spring clutch will tighten
when the hub rotates. The right hand tip of the spring clutch
projects into a notch in the cycle clutch sleeve. The sleeve
fits loosely around, enclosing the spring clutch and acts as a
control for the right end of the cycle clutch spring.