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Type Slug
Figure 12. Type Bar Identification
Figure 13. Changeable Type Bars
is to be used.
The type bar segment is a semi-circular carbon steel casting
with slots cut into it to mount and guide the type bars (Fig. 11).
The segment also provides the mounting for the universal bar,
and the type guide. The rear of the segment is hollowed out
to allow dirt and erasures to be pushed through the slots by the
type bars during their travel to the platen. Two screws and
two pins mount the segment to the segment support.
The type guide is a formed part of heavy metal and is attached
to the segment by four screws and a dowel pin (Fig. 11). The
5
four screws pass through oversize holes in the type guide, so
the guide may be positioned by pivoting it on the dowel pin.
The type guide has two major parts: The ring and the type
guide (Fig. 14)-.
Type Slug
Type
Bar
Ring - part
of
type guide
Type
face makes contact
Figure 14. Type Ring and Cylinder
When a type bar is fully actuated, it contacts the ring when
the type face is approximately .003" from the platen or
cylinder. This relationship is known as proper ring and cylin-
der. During a typing operation, the type bar must whip or
bend above the ring so the type face can make an impression
on the paper. This whipping action prevents the typ'e face
from lingering on the paper.and smearing.
(Operation)
Depression of the key button by the operator causes the rear
end of the key lever to pivot about the fulcrum wire in the
key lever bearing support (Fig. 15). The lug on the bottom
of the keylever contacts the top lug of the trip lever forcing
the trip lever to rotate down unti I its lower lug contacts the
nylon cam. Continued depression forces the cam to rotate
out of its rest position, until the serrations on the nylon heel
of the cam engage the power roll. The distance between the
heel of the cam and the cam rivet is less than the distance
between the toe of the cam and the rivet. This is called the
rise of the cam.
As
the power roll forces the cam to rotate,
the contact point between the power roll and the cam proceeds
from the heel toward the toe. The weight of the type bar and
the tension of the cam lever spring hold the cam against the
power roll. The rise of the cam then forces the cam fulcrum
point, or rivet, away from the power roll, and Causes the
cam lever to rotate about the cam lever fulcrum wire. The
long arm of the cam lever and the type bar link are moved
toward the front of the machine. The link pulls the bottom of
the type bar toward the front of the machine, causing the type
bar to rotate about its fulcrum wire. The type head,leaves
its rest position and begins to travel toward the platen. Be-
fore the type head reaches the platen, the tai I of the cam
contacts the cam knockout finger (Fig. 16). The cam stops
rotating, but the momentum of the type bar causes the type
head to continue toward the platen. This forces the cam lever
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