Mainspring And Cords - IBM Selectric Maintenance Manual

i;~ T;i~'ger
Knock-Off
Eccentric
lATE STYLE
Trigger Disengages
From Torque Bar When
Correct Pawl Clearance
Exists
Trigger Guide
EARLY STYLE
FIGURE 106. Escapement Trigger Guide Adjustmel)t
9. Trigger Lever Upstop - With the machine at rest and a
clearance of .007" to .010" existing between the trig-
ger and the lug on the torque bar, adjust the trigger lev-
er upstop so that it has a clearance of .001" to .005"
with the tri gger lever (Fi g. 107).
/
/
I
\
"-
............
/
. / '
FIGURE 1.07. Trigger Lever Upstop
The trigger upstop prevents the trigger lever from bounc-
ing as it returns to its rest position.
MAINSPRING AND CORDS
I • Gear Mesh - The proper gear mesh between the escape-
ment cord drum and the carrier return pinion involves
two adjustments. Both must be considered together.
a. Adjust the operational shaft laterally so that the
crown surfaces of the escapement cord drum gear
and the carrier return pinion are even (Fig. 108).
Crown
Surfaces Even
2-34
Carrier Return
Pinion
Bearing
Adjust Operational Shaft
End Play By Shift Arbor
And Operational Shaft Collar
FIGURE 108. Gear Mesh and Operational
Shaft Adjustment
The position is controlled by a collar set screwed to
the shaft and the shift clutch ratchet.
Be
sure to
maintain .002" to .004" end play in the operational
. shaft.
b. The escapement cord drum gear should be adjusted
fCiVvuid Oi
back
to
obtain .002"
to
.004" backiash
at the point of tightest mesh with the carrier return
pinion.
Be
sure that no binds exist throughout the
trave I of the carri er.
CAUTION: The mainspring tension should be RE-
LAXED before the escapement cord drum gear is
loosened. The cord tension should also be relaxed
by removing the cord from the pulley on the cord
tension arm. Be sure that no end play exists in the
escapement shaft before attempting the gear mesh
adjustment.
NOTE: No attempt should be made tel adjust the
cord tension with the escapement cord drum because
the drum is set-screwed to a flat spot on the escape-
ment shaft.
2. Tab Governor Pinion - Adjust the tab governor pinion to
have .002" to .004" backlash at the point of closest
mesh with the escapement cord drum gear. Adjust the
pinion by moving both the tab governor hub and collar
located on each side of the pinion. The pinion should
have a minimum of end play yet still rotate freely (Fig.
109).