IBM Selectric - Shift Contact Assembly

7. 1 UC Armature Backstop (Late) (Fig. 81) - Position arma-
ture backstop (armature at rest) so that the UC armature
clears the release arm roller by .005
11
to .020
11
.
Shift Arm
Shift Cam
FI GURE 82. Contact Mounting Plate
SHIFT CONTACT ASSEMBLY
1. Contact Mounting Plate (Fig. 82) - Position vertically
so that the cam follower roller is centered on the shift
cam
surface.
Feedback Contact r~l-~
r
'''''~~l C3, C4 ~@DI
. ~~· ....... T .. "~,
.
I
I! I ransmlttmg 9 I·f)}
I I I I Contact
: I I F a/p
I I I alp I I
Points Aligne.d . U
l
:_~~
Actuatmo Arm I' I I I .
~-~--~--=-h.:;Jf --- ~J ~~~uating
2.
3.
Actuating Tab t t
O/PIS Centered
On Tabs
FI GURE 83. Contact Positioning
Contact Positioning (Fig. 83) - Position the feedback
and transmitting assemblies urtder their mounting screws
for
the following conditions:
a. Operating points centered on actuating tabs.
b. All contact points (or straps) in stack aligned.
Contact Actuating Arm (Fig. 84) - Position (with the
cam follower roller held against the detented shift cam)
so
that the O/P ball is centered between the actuating
arm tabs.
NOTE: If a starting reference is required, form the O/P so
that the center of the O/P ball is 9/16
11
from the contact
mounting plate.
Contact Mtg. Plate
Transmitting Contact
.040"_ ....... o-L..
Actuating Arm- __ ,I: ... !
O/P Ball Centered
FI GURE 84. Contact Actuating Arm
.002" to
N/O Contact
Feedback
Contacts
p.-...-::--~---:7~.~ Or Mode
FIGURE 85. Contact Rise and Air Gap
4. Transmitting Contacts Air Gap (Fig. 84) - Form the N/O
contacts to clear the O/PIS by .040".
5. Feedback or Mode Contact Rise and Air Gap (Fig. 85) -
6.
a. Form the N/C contact supports so that the O/PIS
lift the N/C contact straps .00211 to .005".
b. Form the N/O contact supports so that the N/O
contacts clear the O/PIS by .040".
Actuator Tabs (Fig. 86) - Form so both N/O contacts
receive equal motion as the shift cam rotates through
360
0
•
NOTE: If necessary, the actuator tabs may be formed to
achieve timing requirements - see the timing charts for specifi-
cations.
2-22