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4.
pivot points.
The governor has a spring clutch which utilizes a flat
coiled spring t,o drive a shaft when turned in one di-
rection, and slip on the shaft when turned in the QP-
posite direction •. This clutch consists of a .coi I 'spring,
pinion gear, and clutch collar. The clutch collar IS
fastened, by means of set screws, to the shaft that turns
the governor arms. The pinion gear and clutch collar
are butted together and are connected by the spring.
As
the carriage is moved to the left ,the pinion gear
turns the spring, which tightens itself around the clutch
collar and thereby turns the governor arms. When the
carriage is moved to the right, the spring expands and
slips around the clutch collar. This permits the gover-
nor arms to remain at rest.
The tab check lever, which is mounted on two rivets
through elongated holes, is spring loaded to the ri.ght.
It is moved far enough to the rear to be struck by the
first set tab stop that comes-along.
5.
The tab latch is spring loaded to the right against the
left side of the tab latch keeper (Fig. 50). It is moved
to the rear far enough for it to rotate to the right be-
hind the tab latch keeper. This action latches the tab
lever out where it wi II remain unti I the latch is pushed
off the rear edge of the keeper. The rotation of the
latch is limited by a right angled member of the latch
strik ing a surface of the tab check lever.
6.
7.
Rotation of the pawl re lease lever causes the backspace
interlock to be rotated. Th i s act ion prevents the back-
space powl from entering the escapement rack and al-
lows tabulation to supersede backspace (Fig. 53).
Carriage Return -
Figure 53. Interlocks
Movement of the tab latch stud toward the rear pre-
vents any rotation of the carriage return tab interlock.
This prevents the clutch latch from latching the clutch
and allows tabulation to supersede carriage return (Fig.
53).
The carriage moves to the left and the first set tab stop
moves the rebound check lever toward the front.
As
the carriage continues to move, the stop enters the "V"
slot of the rebound check lever. The rebound check
lever is still under tension of the leaf spring, and im-
mediately snaps out to be latched in its operated po-
26
sition. The tab stop then strikeS the tab check lever,
, mov.ing it to the
J~ft (Fig~
54). The tab check lever
moves the tab latch.to the left unti I it is no longer be-
hind the keeper. At this time the travel of the car-
riage is stopped and the momentum is absorbed by the
horseshoe bracket. The set tab stop now bounces off
the tab check lever and a I lows the tab 'lever, governor
pawl, pawl release lever and bockspoce interlock to
return to rest. At the same time the escapement pawl
returns to the escapement rack
0
,The right side of the
"V" slot in .the rebound check lever restricts the bounc-
ing mot·ion of the tab stop to the right. The pin in the
rebound check lever bracket supports the rebound check
lever in this operation. As the carriage moves to the
left again, it brings an escapement rack tooth against
the pawl, and takes up the sliding motion in; the es-
capement pawl. The rebound check lever is cammed
to rest by the set tab stop which strikes the left side of
the "V" slot and unlatches the rebound check lever
from the pin of its bracket.
Rebound Check Lever Bracket
Figure 54. Rebound Check Lever
The momentary delay between tab lever restoration
and rebound check lever restoration makes it neces-
sary to have a rebound check interlock (Fig. 53). ,
This interlock prevents the rebound check lever from
catching a set tab stop when a carriage return oper-
ation occurs immediate Iy after the tab lever goes to
rest. The interlock will move to the left and cam the
rebound check lever back to rest when the clutch lever
is latched. This will prevent a lockup of the carriage.
If,
on the other hand, a set tab stop happens to
be
bearing against the rebound check lever at the instant
the clutch tries to latch, the resistance of the rebou~d
check leverwill prevent the clutch from
latchin~,i(:md
all parts wi II return to rest after a line space oper~ion.
The operator may tabulate when there are no set tab
stops to the right of the tab check lever. When this
occurs, the right rna rgin stop moves the margin control
lever to the left. This moves the tab check lever to
the left and un latches the tab lever. If the tab lever
is latched out beyond the right margin stop and no tab
stops are set, the final stop on the right end of the
ta~
rClck wi II serve as an unlat'ching device.
Tab levers used on the 8, 9, and 10 pitch typewriters
will have no identifying mark. The 12 pitch tab levers
...
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