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'margin control levert which is. located just below the margin
rack. The margin stops encircle the margin rack and contain
!eeth that mesh with those on the rack (Fig. 23). The number
of teeth per inch correspond to the pitch of the· machine.
The margin set is designed to allow the operator to reposition
the margin stops without moving her hands from the keyboard.
To change the margin, the operator must follow four steps:
position the carriage at the existing margin; then depress the
margin set button; move the carriage to the desired position
with the button held down; then release the button and check
the position by operating the carriage return.
The front end ofthe margin set key lever has a bottom lug with
an angular camming surface that contacts the carriage return'
key lock
(Fig~23).
The upright extension on the rear of the
key lever receives the adjustable clevis on the margin set link.
The rear of the link is attached to a lever on the margin set
shaft. The right end ofthe shoft is pivoted on the right side
frame and the left end is pivoted on the right-hand motor
bracket. A rocker arm is attached to the left side of the shaft
and contacts a stud on the bottom of the margin set lever.
The margin set bracket has countersunk holes where the
chamfered ends of the margin set lever hub contact the' bracket.
The bracket is held to the inside of the rear frame by two
screws, one of which goes through the motor bracket. Earlier
brackets did not extend down as far on the rear frame and did
not have countersunk holes for the hub of the set lever. Prior
to the use of the screw and stop nut, a pin and two C-clips
were used to mount the set lever on the bracket. The changes
were designed to eliminate side play in the margin set lever.
(Operation)
When the margin set key lever is depressed, its bottom lug
cams the key lever locking bar into a position that locks an
operations except: backspace, space bar, shift and margin
release. This protects the margin set mechanism from damage
by carriage return or tabulation while setting margins. The
upright extension on the key lever pulls the margin set link
forward so the lever on the margin set shaft rotates forward.
The rocker arm on the margin set shaft moves the bottom of the
margin set lever to the rear. The margin set lever rotates about
its fulcrum point, and the front end of the lever is lowered.
With the carriage at either margin, the margin set lever will
contact the margin stop and lower it farenough to disengage
it from the margin rack. With the margin. set keybuttoh held
down, the carriage may be positioned by using the space bar,
backspace, or carriage' release levers. The new position of
the carriage wi II also be the new position of the margin stop
after releasing the margihset key button.
Carriages longer than 12" require one or more center supports
attached to the margin rack to make the rack rigid. These
center supparts obstruct the travel of the margin stops. Margin
setting is therefore restricted to an area bounded by a margin
rack center support and the extreme left or right margin.
MARGIN RELEASE
Margin release provides tlie,operator with a means of releasing
the carriage from the restriction of either the left or tight mar-
gin stop without moving the stops. Margin release is used to
lower the margin control lever enough to allow the margin
10
stops to pass. This permits additional carriage travel from
the
position of the set margin stop to the carriage final stop, yet
retains the margin stop setting for further use.
The margin release key button is attached to the front end of
a long key lever that extends back to the tab actuating lever
on the governor control bracket assembly (Fig. 24). The mal'-
gin release key lever does not extend into the front guide
comb. A shoulder screw mounts the key lever to the poWer
frame and serves as its fulcrum point. The motion of the key
lever is restricted by the key lever fulcrum wire within the'
elongated slot in the key lever (Fig. 24).
Figure 24. Margin Release Key Lever
When the key button is depressed, the key lever pivots on its
fulcrum screw. The rear of the key lever contacts and raises
the margin release eccentric, which is attached to the tab
actuating lever. The tab actuating lever raises by rotating on
its mounting rivet. A hook extension on the top of the actu-
ating lever is positioned in a slot in the left end of the tab
lever.
The actuating lever raises the left end of the tab lever, using
the tab lever pivot screw as a fulcrum point. The margin con-
trolleveris lowered by this operation, as it is a part of the
tab lever assembly. The margin stops may now pass over the
margin control leve.r.
Earlier machines used a different key lever arrangement which
required more force on the key button
0
Depression oithe key-
button raised the rear end of the margin release key lever qnd
its link. The link rotated the margin release bellcrank which
moved a push rod toward the rear (Fi g. 25). The push rod
rotated a small bellcrank mounted on the governor control
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