Selection Contact Assembly - IBM Selectric I/O Manual Of Instruction

Selector Latch Pusher
The selector latch pushers pivot on a shaft that is mounted to
the power frame by a bracket.
There are seven latch pushers; one for each selector latch, in-
cluding the code check latch.
The purpose of the latch pusher is to move the unwanted se-
lector latches forward from under the selector-latch bail.
The latch pushers are spring loaded toward the pusher bail.
When the bail rises, the tail of the pusher follows the bail.
As the pusher pivots on the shaft, the operating end or top of
the pusher moves forward, contacting a selector latch. The
latch wi II be pushed forward, away from the bai I (Fig. 48).
Latch Extension
Latch Pusher
Tail
Selector - Latch Pusher Bail
FIGURE 48. Selector - Latch Pusher
It is important to note that the selector armatures that were not
attracted wi
II
keep their respective latches from being oper-
ated. This is accompl ished by the tai I of the pusher contact-
ing the latching surface in the notch of the armature as the
pusher starts to rise (Fig. 47).
Because the armature kept the tai I of the pusher from rising,
the pusher could not push the latch away from the bai I. There-
fore, the selector latch is left under the selector-latch bail
to be operated as the bai I moves down.
Restoring the Selector Latch Pushers
The selector latch pushers are restored by the selector-latch
pusher bail. The bail forces the tails of the pushers down,
causing the pushers to pivot on a shaft. The top of the pusher
moves to the rear, allowing the selector latches to return
under the selector-latch bai I.
The pusher. bail must restore the pushers far enough to allow
the armatures to fully restore. The tails of the pushers should
be in the notch of the armatures. At rest, the tai Is of the
pushers are against the pusher bai I and should not be touching
the armatures (Fig. 49).
18
Pusher Bail
FIGURE 49. Latch Pusher Restoring
Selector Armature Knock-off
Armature knock-off is provided to overcome any residual mag-
netism and to insure that the armatures restore quickly.
The cycle clutch trip bail provides a positive knock-offforthe
selection magnet armatures. An eccentric knock-off stud on
the pusher-bail cam-follower arm restores the cycle clutch
trip bail. The trip bail restoring imparts the knock-off to the
selector armatures (Fig. 50).
Pusher
Cam Follower
FIGURE 50. Selector Armature Knock-off
SELECTION CONTACT ASSEMBLY
The selection contact assembly is mounted to a bracket that
is fastened to the power frame. It is located directly below
the selector latches. The upper contacts are used for code
check and the bottom contacts are the transmitting contacts
(Fig. 51).