IBM Selectric I/O Manual Of Instruction page 53

I
As the low velocity print operation is completing, the follower
restores back to the high part of one of the cam lobes on the
low velocity cam. This relaxes the pull on the velocity con-
trol cable so that the yoke actuating lever spring (Fig. 105.4)
will shift the print cam follower roller back to the right under
the high velocity lobe of the print cam.
If a high velocity character is selected at the keyboard, the
low velocity latch will remain at rest in the operating path of
the stop on the cam follower. The cam follower is restricted
from following the contour of the cam towards its low point
therefore, no pull is felt on the velocity control cable. The
print cam Jollower roller remains to the right under the high
velocity lobe of the print cam and a high velocity print oper-
ation results.
To prevent the print cam from interfering with the print cam
follower roller as it shifts from one cam lobe to the other dur-
ing a velocity selection operation, the print cam follower and
roller is held disengaged from the print cam until the roller
has shifted. This is accomplished by an adjustable stop screw
located directly under the rear portion of the print cam fol-
lower (Fig. 105.10). The stop screw, which is threaded
through a triangular shaped screw, disengages the print cam
follower roller from the print cam as the cam approaches its
rest position. The shifting of the roller occurs at the begin-
ning and at the end of a low velocity print cycle which is
just when the print cam is leaving or approaching its rest
position.
Print Cam
Print Cam Follower
And Roller
• FIGURE 105.10 Print Cam Follower Stop Screw
The velocity control cable consists of a thin strand of wire
(with eyelets at each end) running through the center of a
flexible plastic-coated sheath. The wire slides freely within
the sheath transmitting motion from the low velocity cam fol-
lower to the yoke actuating lever on the carrier. Both ends
of the cable sheath are clamped rigidly to their respective
mechanisms by cable clamps (Fig. 105.5 and 105.7). Clamp-
ing the ends of the sheath allows the velocity control cable to
operate efficiently as a motion transmitting device.
The velocity control cable passes through a wire guide located
on the left side of the carrier as shown in (Fig.1051l). The
guide retains the cable against the underside of the carrier so
that the cable will not hand down and rub on the dust shields
or catch in the mechanism while the dust shields are removed.
• FIGURE 105 .. 11 Cable Guide And Cable Deflector
A cable deflector attached to the escapement bracket (Fig.
105 .1l) prevents the velocity control cable from getting be-
hind the carrier.
The cable is also clamped along the rear edge of the dust
shields by a center cable clamp on the powerframe and a
guide lug on the right hand dust shield (Fig. 105.12). The
center cable clamp maintains the cable in its correct lateral
position so that the carrier is free to travel the entire length
of the carriage without being restricted by the cable.
• FIGURE 105.12 Center Cable Clamp
Low Velocity Magnet Assembly
This magnet is mounted on the right hand keyboard frame, un-
der the low velocity latch (Fig. 105.13).
41. 3