IBM B-1 Instruction Manual page 8

cam, and the trip lever (Fig. 15).
The cam consists of a steel body with nylon molded at the bear-
ing point, the tai I, and the shoe that contacts' the power roll.
The cam is mounted to the cam lever by means of a shoulder
rivet. It is free to rotate about the rivet, but the amount of
rotation is limited in one direction by a steel stop which pro-
jects from the cam. The stop contacts the side of the cam lever
and determines the rest position of the cam (Fig. 15). A cam
spring extends between a hook on the cam lever and a hook on
the cam and holds the cam in its rest position. The heel of the
nylon shoe contacts the cam lever when the cam is fully rotated
and limits rotation in this direction. Earlier steel bodied cams
did not have steel stops. The nylon heel of the cam was larger
and served as a cam stop in both directions of cam rotation.
The st.eel stop was incorporated to minimize cam bounce when
the cam returned to its rest position.
The trip lever is mounted to the cam lever by a shoulder rivet
(Fig. 15). An elongated slot in the trip lever allows it to slide
front to rear to rotate around the rivet. A hook on the trip
lever mounts a sprint that extends to a hook on the cam lever.
The tri I lever springs holds the trip lever up and to the rear in
its rest position. The trip lever has two formed lugs. The top
lug is positioned directly under the lug on the key lever. The
boftom lug is directly above the cam.
Impression Control Indicator
Figure 10. Cam Knockout Bar Assembly
The cam knockout bor assembly is an aluminum casting to which
two sets of flat knockout spring fingers are secured (Fig. 10).
There is one knockout finger for each cam lever assembly. The
height of each knockout finger, is controlled by individual
impression control screws which are located in the knockout bar
below the fingers. The knockout bar assembly pivots between
the left and right side frames on two pins that are secured by
set screws. An impression control eccentric shaft is positioned
beneath the rear of the knockout bor and pivots in two bronze
bearings which are mounted to the left and right side frames
(Fig. 10). A plastic gear is pinned to the left end of the shaft
and meshes with the teeth on the impression control indicator.
The impression control indicator pivots on a stud on the left
side frame. The rear of the knockout bar is held down against
the impression control eccentric shaft by two springs.
4
Type Bars
Type bars are mounted in a slotted segment and are held by a
curved type bar fulcrum wire (Fig. 11). The lower end of the
type bor extends below the segment and has a hole in it for
the type bar link. Above the segment is the body of the bar,
identified by the reinforcing rib, and the type head which
includes the type slug and the wider section of the bar (Fig.
12). The part referred to as the throat extends from the top
of the reinforcing rib to the bottom of the head. A type mark,
used to identify the type style, is located between the upper
and lower case type faces on the type slug. An anticlash
I ug prevents damage to the type face if one type bar fo Ilows
another to the platen before the first bar has gotten out of the
way. The type face is curved to the same arc as the platen
so that all parts of the type face will strike evenly. A hole
is provided in the type head to facilitate forming of the head
during type alignment. A locater lug found on some type
styles is used at the factory to facilitate soldering of the type
slug to the bar.
Fulcrum Wire Ret.aining Screws
Figure 11. Type Bar Mounting
Changable type bars are available to permit the operator to
interchange type bars in specified positions, thus providing
a greater number of special characters (Fig. 13). This feature
is available only for positions 0, 32,36, 39, 40, 41, 42, 43,
and the standard numerical type bar positions. Changeable
type bars ore not porvided for alphabetic positions or position
#38. A special type bor link incorporating a spring clip is .
used with changable type bars. This link will not drop off the
cain lever when the operator removes a type bar and drops the.
link.
Each changable type bar is designated for one type bar posi-
tion only and is to be aligned to the typewriter for which it