Shift Contact Assembly - IBM Selectric Reference Manual

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