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The operation of the carriage return mechanism depends upon
the position of the carriage when the operation is started. If
the carriage is located at any position but the left margin, a
full carriage return operation takes place. 'If the carriage is
located at the left margin, the carriage return operation re-
duces to a line space . . operation.
.
Consider first a full carriage. return ·operation. The carriage
return key lever releases the single lobe functional cam at the
right end of the power roll (Fig. 56).
As
the cam rotates, the
cam frame pulls the front clutch lever link toward the front of
the ma·chine. This rotates the .clutch lever counter-clockwise
about its mounting. The slot in .the clutch lever moves to the
left and, by means of a stud within this slot, moves the top of
the clutch operating arm in the same direction. The bottom of
the operating arm is mounted on a pivot shaft, one end of
which is spring loaded to the left by a compression spring (Fig.
57). This provides an adjustable control on the amount of
pressure the operating arm wi II bring to bear against the clutch
plate. The oPerating arm pushes the clutch plate against the
clutch disc. The clutch disc is mounted on the power roll
shaft so that it is constantly turning with the power roll. The
clutch plate and clutch pulley are joined by three studs that
cause them to rotate together. The clutch disc is now forced
against the clutch pulley and causes it to rotate and wind up
the carriage return tape.
One end of this tape is attached to the pulley, and the other
end to a stud on the. index pawl carrier (Fig. 58). The initial
pull on the tape line spaces the platen and then the carriage
is pulled
to
the right. The clutch lever also moves the rear
clutch lever link forward and rotates the lower bellcrank,
moving the pawl release link toward the right (Fig. 56). This
link rotates the pawl release bellcrank, which contains a lug
that projects toward the rear. This lug rises striking a hook
shaped projection on the intermediate pawl release lever
causing this lever to rotate and strike the pawl release lever
(Fig. 59). Rotation of the p~wl release lever removes the
escapement pawl from the rack. The pawl
relea~e
lever also
oPerates the backspace interlock so that the backspace pawl
cannot enter the rack during a carriage return operation.
As
the carriage return cam reaches its high point, the clutch
lever is rotated far enough to allow the clutch to rotate under
tension of its spring until it latches the clutch lever in the
operating position (Fig. 60). The latch moves the clutch latch
Clutch Lever Bracket
Adjusting Screw
Clutch Lever Bracket
Figure 57. Clutch Mechanism
28
Una
Position Reset
Figure 58. Indexing Mechanism
Pawl Release Lever
Figure 59. Pawl Release
Clutch Latch
"latch rotated under spring tension
_CI"tch-OPE"ating Arm
All clutch parts at rest
latching
Clearance
Carf'iage return cam
rotated
to
high point
it--Clutch Latch
figure 60. Clutch Latch Operation
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