Escapement Mechanism - IBM Selectric Manual

NOTE: Too l;ttle clearance may prevent latching of
the low velocity latch resulting in a continuous low
velocity operation for all characters. Too much clear-
ance might allow a slight pull to be produced on the
cable duringa high velocity operation which could shift
the follower roller partially onto the low velocity lobe.
12. PoweredTravel-With the cycle shaft latched at rest
and the impression control lever set at position 4, loosen
the binding screw and move the detent plate forward or
back unt i I a cl earance of .250" exi sts between the pi aten
and the center of the letter "Z" (Fig. 92). This clear-
ance can easi Iy be measured with the foot of the Hoover-
ometer which is approximately .250". When measuring
the adjustment, remove the tilt ring play by depressing
lightly on the rear of the tilt ring.
Hooverometer
FIGURE 92. Powered Travel
CAUTION: The copy control lever must be positioned
all the way forward when making adjustments #12 and
#13.
13. Free Flight - Set the impression control lever at 4 and
then hand-cycle the machine until the print cam follower
roller is resting on the high point of the print cam. At
thispoint .035" of free flight should exist between the
platen and the center of the letter "Z". Adjust the
eccentric on the impreS$ion control lever to obtain this
condition(Fig.93). Keepthe high part ofthe eccentric
forward.
NOTE: The pusher end of the large spri ng hook measures
approximately .033"andmaybeusedtogauge this clear-
ance. When measuring this clearance, remove the tilt
ringplaybydepressinglightlyonthe rear of the tilt ring.
CAUTION: Each of these adjustments (powered travel
and free fl ight) directly affect each other and must be
adiusted alternately until both are correct.
35
Impression Control LeverLOrge
s~
1.
Eccentri c
FIGURE
93.
Free Flight
ESCAPEMENT MECHANISM
E sca pement Bracket - Ad just the escapement bracket
front to rear so that .011" to .017" clearance exists be-
tween the escapement bracket and the tab torque bar
(Fig. 94). Keep the rear surface of the bracket parallel
to the torque bar. The clearance should be observed be-
tween the flat part of the bracket and the torque bar.
Disregard the raised area that acts as a back-up for the
torque bar on later level machines.
NOTE: The following relationships are affected by the
position of the escapement bracket - tab lever trigger
to tab torque bar, tab lever pawl to tab rack, tab lever
to escapement and backspace pawls, tab lever trigger
to tab overthrow stop, escapement and backspace pawls
to escapement torque bar, escapement torque bar to pawl
pivot stud, and escapement torque bar to tab latch.
Each of these relationships must be checked and re-
adjusted ifnecessaryafter any adjustment of the escape-
ment bracket.
. a
1 111 to .017"
Escapement Bracket
Positioned To Obtain
Clearance
Check Entire Length Of Writing line
For Possible Warped Torque Bar
FIGURE
94.
Escapement Bracket