IBM B-1 User manual

IBM ELECTRI€ TYPEWRITERS
"
CUS ,rOMER ENGINEERING
. '\
, B-1

ELECTRIC
IBM
TYPEWRITERS
CUSTOMER ENGINEERING INSTRUCTION MANUAL
MODEL B1
Issued to __________________ _
Branch
Office ________________ _
Department
___________________ _
Address
__________________ _
If lost or mislaid, finder will kindly return to the above address
INTERNATIONAL BUSINESS MACHINES CORPORATION
New York 22, New York

CONTENTS
Motor and Drive -------------------------
Key Levers, Letter Cams and Type Bars ---------------
Escapement ---------------------------
Margin Set - - - - - - - - - - - - - - - - - - - - - - - - - - -
Margin Release -------------------------
Line Lock ----------------------------
Carriage and Rai Is - - - - - - - - - - - - - - - - - - - - - - - -
Paper Feed - - - - - - - - - - - - - - - - - - - - - - - - - - -
Platens -----------------------------
Functiona I Cams -----
Space Bar ------
Shift - - - - -
Tabulation --
Carriage Return
Backspace ---
Ribbon - - - - - - - -
© 1958 by
INTERNATIONAL BUSINESS MACHINES CORPORATION
590 Madison Avenue, New York 22, New York
Printed in U.S .A. May 1958
FORNVPART NO: 241-5010-1
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IBM ELECTRIC TYPEWRITER
MODEL··Bl
INSTRUCTION MANUAL
MOTOR AND DRIVE
Motor.
The
AC and the DC motor used in the Model B, IBM Electric
Typewriter
is rated at 1/40 HP. It is equipped with self-
aligning bronze bearings which are surrounded with saturated
oil wicks and oil return cups.
The
AC motor operates on the induction principle and runs at
a speed of approximately 1625 R.P.M. No governor brushes
or starting contacts are required, thus assuring quiet operation
(Fig. 1). A two mfd capocitor, in the starting winding circuit,
provides the means to start the motor and control the direction
of rotation. The capacitor also remains in the circuit whi Ie
the motor is running and is used to minimize operating vibrations
(Fig. 2).
Motor Mounting Shaft
Figure 1. AC Motor And Mounting
The capocitor is wrapped in insulating material and mounted
to the rear frame by the capacitor mounting bracket.
The switch is mounted on the right side frame. It is operated
by a switch lever and link. The switch lever has a white
portion for
the "ON" position to attract attention. It moves
the key lever locking bar .to the left and to the front when the
switch is turnedUOFF" (Fig. 27). This locks all keylevers ex-
cept the shift key lever. The shift key lever is not affected
because in the locked down upper case position, it wouldob-
struct the action of the key locking bar~
The DC motor is a shunt \Hound brush motor, in which speed
is
dependent on stable line voltage (Fig. 3). This motor is
characterized by a.low starting torque and astable speed under
load. Advantages of this motor are that it requires no gover-
nor or governor contacts and requires only a simple switch cir-
cuit and a fuse. Changing machine specifications from one
1
White
llac:lc Gray
sJitch
capacitor
Figure 2. AC Wiring Diagram
current to another is simple and fast, because the same mount-
ing parts are used for both AC and DC motors. However, when
changing a machine
from' AC to DC, a nonmagnetic governor
pawl assembly must be installed. The standard governor powl
can become magnetized by a DC motor and magnetically at-
tach itself to the friction governor plate and cause faulty tabu-
lation and escapement.
Black
Figure 3. DC Wiring Diagram
The AC and DC motor is suspended from ci shaft that is sup-
ported by the left side frame and a motor mounting bracket on
the rear frame. This shaft is held in place by C-clips. Rub-
ber grommets, held in cup like recesses
of the motor end bells,
insulate the motor vibrations from the shaft. A lower grom~et
insulates the motor from the nut and screw that positions the
motor on the left side frame (Fig. 1). The latest rubber motor
mounts
or .grommets incorporate a "finned" design to reduce
motor noise
(Fig. 4).
To further reduce vibration and harmonic noise transmitted
through the motor mounts, a ring mount is now used on 115V
and 230V 60
cycles AC motors (Fig. 5). The three mounting
holes in the frames used for the previous motor, are also used
by the ring mount.
In addition, a ring mount bracket support
has been added to eliminate any left or right motion of the
right ring mount bracket.
Every motor mounting includes a static eliminator, which
grounds
the motor to the frame of the. typewriter. A small
piece of copper wire is formed in a "U" around Qneof thegrom'
mets or rings to .prevent the bui Id-up ofa static charge.

Upper Motor Mount -*""--I-NIIII
Stotic Eliminator
/litl
Lower Moior Mount
Figure 4. n Finned II Motor Mounts
Ring Mounting Bracket
Figure 5. Ring Mounted Motor
Two bakelite shields, formerly used, have been eliminated on
all motors. This allows a greater flow of air through the motor
thereby reducing its operating temperature.
Drive
The positive drive mechanism consists
of toothed belts and pul-
leys to transfer the rotation of the motor to the power roll (Fig.
6). speed reduction from the motor to the power roll is approxi-
mately6: 1. This reduction is accomplished by using a combi-
nation
of 3 pulleys and 2 belts. A drive belt transfers the ro-
tation from the motor pulley to the large side of the inter-
mediate pulley. A belt from the small side of the intermediate
pulley, known as the driven belt, transfers the rotation of the
intermediate pulley
to the power roll pulley. The power roll
pulley is aj'tached directly to the end of the power roll shaft
by two bristo
set screws.
The intermediate
pulley ~s mounted to the left side frame by
means
of an intermediate shaft, a retaining plate and a nut.
The retaining plate acts as a locking device for the nut. The
shaft and nut have a left-hand thread
so that the rotation of
the pulley prevents loosening of the shaft.
2
Figure 6. Positive Drive Mechanism
The pitch of the machine is the number of typed characters or
spaces
to the inch. Machine pitch usually is determined by
the size of the type used. Type style and size also indicate
the power. roll speed needed for best impression results. The
speed
of the power roll is varied by using motor pulleys of
different diameters. The diameter of the motor pulley deter-
mines the number of teeth on the pulley, and these numbers
are molded on the pulley.
The drive belts vary in diameter to compensate for motorpul-
ley sizes. This facilitates belt adjustments on shaft mounted
motors. Strips
of yel)oV( or green paint on the drive belts
indicate the small and large belts, respectively.
The following chart provides recommendations for the proper
motor
pulley, drive belt and power roll speed on most ma-
chine.s of a given pitch.
Pitch Power Roll Speed No. of Teeth Drive Belt
FPM RPM
on Mtr. Pulley
12 and 14 95 242 14
Y~llow
6.2/5, 8,
9,
and 10
103 261
15
Green
;-1,1;',
The ring mounted. motor must be kept toward the rear to pre-
vent interference with the lower line'lock bell crank. It is,
therefore, necessary to use the longer green belt with all ring
mounted motors, regardless
of the motor pu lIey used.
Earlier model positive,belt drives had motor
pulley combi-
nations
of 13 - 15 teeth and 14 -16 teeth. Power roll speeds
. of 95 and 103 feet per minute are the only ones currently speci-
fied, therefore a 14 -15 tooth motor pulley has replaced two
previous pulleys.
The purpose
of the power roll is to supply motion for all cam
operated mechanisms. It consists of a hollow met,af cylinder
to which a rubber tube. is glued (Fig. 7). Two end plugs,

Power Roll Drive Pulley
locknut @t;D
Power Roll ~~
Io.!l'--=="-. Clutch lever Retaining Bolt "'/l f
Coiled Compression Spring
Figure 7. Power Roll Mechanism
containing a solid power roll shaft, are pressed into the ends
of the cylinder. This shaft mounts the power roll to the ma-
chine by passing through self-aligning porous bronze bearings
that are held in retainers on both side frames. The left end of
the shaft is the mounting for the power roll pulley. The right
end
of the shaft is rectangular and extends through a rectangu-
lar hole in the clutch friction disc.
KEY LEVERS, LETTER CAMS AND TYPE BARS
Letter Key Levers
The
~ear ends of the keylevers are mounted in slots in the key
lever bearing support and are held by a fulcrum wire which
passes through a hole
in each key lever (Fig. 8). This wire
serves as the fulcrum point for all
key levers. The left to
right motion
of the front ends of the key levers is limited by
slots in the front key lever guide cotnb (Fig. 9). Key lever
Com lever Bearing Support
Figure 8. Key Lever and Cam Mounting
3
springs hold the key levers in the raised, or rest position. 'The
springs
are located between the front ends of the key levers
and the
~pring lugs on the top of the front guide comb (Fig. 15)
The travel of each key lever is limited by strips of rubber
mounted across the top and bottom
of the slots in the front
guide comb. The rubber strips prevent metal
to metal contact
and are a noise reduction feature. A sponge rubber keyboard
stabi lizer reduces
key button vibration during machine oper-
ation (Fig. 15). It is located between the adjusting lugs on ..
the top of the key levers and the key lever bearing support.
The adjusting lugs make it possible
to raise or lower individual
key levers.
Figure 9. Key Lever Guide Comb
Letter Cams
Cam lever assemblies
are mounted in slots in the cam bearing
support and
are held by a fulcrum wire which passes through
a hole
in each cam lever (Fig. 8). A type bar link is hooked
through a hole
in the long arm or extension of the cam lever.
The other end of this link hooks into the bottom of the type
bar. The rest position of the type bar, against the type rest,
determines the rest position
of the cam lever. When the type
bar
is fully actuated or against the platen, the cam lever is
also rotated to its full actuated position. Each cam lever
assembly is made up of three main parts; the c.am lever, the

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

Type Slug
Figure 12. Type Bar Identification
Figure 13. Changeable Type Bars
is to be used.
The typebar 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
typebars 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

Letter ... aRI _____ ~_:!'
Steel Stop
~~~,-~
Eccentric Shaft Screw Cam
Fulcrum
Figure 15. Cam and Type Bar Operation
to continue its motion toward the front of the machine. Con-
tinued motion of the cam lever causes the nylon shoe on the
cam
to leave the power roll and the cam spring restores the
cam to its rest position against the cam
lever. The moving
type bar
contacts'the ring, then whips or bends, abave the ring
so the type head may complete its travel into the type guide.
The type face strikes the ribbon and makes its impression on the
paper. The striking force or impression of each type bar is
determined by how long the cam is allowed to rotate against
the power roll before it reaches the knockout finger. The
long-
Cam Lever Fulcrum
Figure 16. Cam Knockoff Point
6
er the cam remains engaged with the power roll, the longer
the type bar wi II be powered and the greater will be its strik-
ing force.
After the type bar strikes the
platen, the type bar and cam
lever reverse their direction. If the key lever is helddowrl,
the rear edge of the top lug on the trip lever will engage the
front edge
of the lug on the key lever as the cam lever as-
sembly restores. The cam leverwill restore to its rest position,
but the
trip lever wi II remain against the key lever lug unti I
the key lever is allowed to restore. The restoration of the
key lever allows the trip lever spring to restore the trip lever
up toward the rear of the machine. This actioD of the trip,
lever insures a single operation of the cam and allowsthe type
bar to restore
to the rest position, regardless of how long the
operator ho Ids the key button depressed.
When the type bar r-.eturns to rest, it strikes a spring loaded;
rubber type rest pad, which is suspended between two frames
on the segment support (Fig. 11). The type rest reduces type
bar rebounding away
from the rest position and reduces nois~.
This enables th'e type bar to be ready immediately for another
operation.
The impression of the type bars can be controlled by two
methods.
An impression control screw isprovided below each
knockout finger to give individual .adjustment for this impres:"
sion
of each typebar (Fig. 10). An impression control indi-
cator is available to the operator, to provide a means of regu-
latingthe height of the knockout bar assembly (Fig. 10). This
adjusts the knockout point
of the cams as a group. Moving
the impression control indicator rotates the ec,centric shaft
below the cam knockout bar assembly. Raising the bar de-
creases the impression of all type bars, and lowering the bar
increases the impression
of all type bars. A reference scale,
graduated from 0 to 10, is on the impression control indicator.

Repeat/Non Repeat Key Levers
A repeat/non repeat underscore is provided as standard equip'"
ment. A one piece repeat key lever, a plunger and a spr~ng
ore used with a standard cam unit to provide thi-s feature. The
keylever has a two step key I.ever lug. The front guide comb
has six positions where
repeat/non repeat letter units may be
installed
at the factory: 0, 8, 32, 36, 39, and 42 (Fig. 9).
Installation requires the removal of the rubber from the front
.guide comb where
the repeat character is desired. Two dif-
ferent plunger springs are available; the lighter spring is to be
used with key levers in the upper two rows.
Figure 17. Repeat/Non Repeat Key Levers
Escapement
Tr:jp Lever
When the repeat/non repeat key lever is depressed to the limit
of its normal travel, the rear step on the key lever lug will
provide a single operation
ofthe cam (Fig. 17). If the key
lever is held down in this position, the rear step on the key
lever lug will prevent the trip lever from restoring. Further
depression
of the key lever is allowed by the spring loaded
plunger. This will cause the front step of the key lever lug to
depress the trip lever for a repeat action of the cam. If the
key lever is he Id down in this position, the trip lever wi II be
cammed down by
the front step on the key lever lu"g, each
time the cam lever assembly restores from a former operation.
A special two piece key lever is used for field installation of
a repeat/non repeat character in any letter position desired
(Fig. 17).
This feature may be .crippled when a plunger and spring is used
by installing a plunger bushing in place of the compression
spring. It
is necessary to replace the plunger with the space
,bar plunger in order for
the bushing to be used.
ESCAPEMENT
The escapement mechanism controls movement of the car-
riage. The mechanism consists of the universal bar, escape-
ment pawl, and the escapement rack (Fig. 18).
The universal bar and universal bar support
are fastened to the
back of the segment with two hex headed screws. Flexible
mounting springs
connect the universal bar to the support and
position the universal bar against the back of the segment.
The escapement powl bracket
is fastened to the rear rail with
Yigure 18. Escapement Mechanism
7

two screws. A single escapement pawl is mounted on the
escapement pawl bracket by a shoulder rivet passing through
an elongated hole-in the pawl. An escapement 'pawl spring
pulls
the escapement pawl tip to the right and into the escape-
ment rack. The escapement pawl spacer cont$lins a larger
elongated hole and is ~ounted ,on the same sholllder rivet as
the escapement pawl. A short pawl spacer spring loads the
spacer toward the right and to the rear. Also mounted to the
pawl bracket with another shoulder rivet is the escapement trip
lever.
The escapement rack is secured ot the underside of the car-
riage with dowel pins and screWs. It contains a number of
teeth per inch corresponding to the pitch of the typewriter.
(Operation)
The escapement is asingle pawl type operated each time a
type bar moves to the platen, or whenever the space ,bar mech-
an ism is activated.
As the type bar moves toward the platen, it contacts the uni-
versal bar and pushes it toward the rear. An adjusting plate
mounted on the universal bar transfers the universal bar motion
to
the escapement trip I ink. Motion of the trip link toward the
rear rotates the escapement trip lever, on its shoulder moLint-
ing rivet, so that the top of the trip lever moves toward the
front of the machine. The top of the trip lever contacts an
upright lug on the escapement pawl sP<;lcer, part of which is
behind the tail of the escapement pawl, and rotates the left
erid
of the escapement pawl spacertoward the front of the type-
writer. As the upright lug moves forward, it carries the tail of
the escapement pawl forware. The escapement pawl pivots
abaut its shoulder mounting rivet, and the pawl tip is removed
from the escapement rack (Fig. 19).
Elongated Mounting Hole
Carriage held by escapement pawl
~:;::
Pawl spacer trips pawl from rack __ J\J\.!\IIJ\I\JV __
Pawl spacer still forward
Carriage must overcome inertia
before it moves.
After escapement paWl resh?res to next
tooth of rack, corriege starts ~. move
Carriage completes movement
under mainspring tension
Figure 19. Escapement Pawl Operation
8
After clearing the rack tooth, the escapement pawl snaps to
the right under tension of the pawl spring and immediately
contacts the next rack tooth. The type bar continues on toward
the platen and prints, causing the pawl spacer to continue its
forward travel. A portion ofthe escapement pawl bracket
serves as an overthrow stop and prevents the spacer from get-
ting in front of the pawl tait., As the type bar reverses its
direction, the pawl spacer spring restQres the spacer to the
rear, clear of the escapement pawl tai I (Fig. 19).' Because
of its relatively heavy mass and inertia, the carriage does not
move until
all of these actions have taken place. As the car-
riage moves to the left under tension of the main spring, the
escapeme,nt pawl is pushed to the left unti I the edge of its
elongated mounting hole contacts the mounting rivet. This
stops and holds
the carriage. The tai I of the escapement pawl
is again in front ofthe escapement pawl spacer lug (Fig. 19).
Thus,
the escapement mechanism completes one operation and
is in position for the next.
The motion described above occurs under power operation
only; if a type bar is raised to the platen by hand, the car-
riage and escapement pawl wi II move before the escapement
pawl spacer restores. The elongated slot in the escapemen't
pawl
spacer a I lows the spacer to be moved to the left past 0
the tail of the escapemerit pawl and prevents either damage to
parts
or jamming of the carriage. As the type bar moves away
from the platen the spacer wi" restore to its norma I rest po-
sition.
Maximum escapement speed is obtained by keeping the escape-
ment pawl spacer overthrow to a minimum after the tripping
point has been
reached. This permits the spacer to restore as
rapidly as possible.
Each time
the escapement pawl is operated, main spring tension
is allowed to move the carriage one space to the left~ Mounted
tq the power frame casting is the main spring and holder as-
sembly containing the main spring (Fig. 20). The main spring
drum rotates about a mounting stud which passes through
the
center of the main sp,ring and into the power frame. Tension
is appl ied to the main spring drum by the main spring and
transferred to the carriage by, the tension tape. A loop on the
end of the tension tape is attached to the carriage by one of
Lug of main spring drum
Figure 20. Main Spring and Holder Assembly

two methods. Early 12" and 16" tapes used a hook fastener
which was secured
in a hole in the carriage bed with a rubber
plug
(Fig. 21). Currently all tension tapes are screwed to the
right end of the escapement rack.
An improved main spring and holder assembly was introduced
ahead of the present centrifugal· governor mechanism. It was
designed to provide a more constand
carriage tension by the
use of a cross curve spring. This spring replaced the former
style and was designed
to minimize failures during repeat space
bar operations and also to provide for a less critacal tab friction
governor
adjustment. Early main spring and holder assembl ies
were mounted to the power frame with two screws which
pre-
vented the holder from turning (Fig. 21). The improved as-
sembly mounts to the power frame by the main spring drum
mounting
stud. An ear on the holder contacts the power frame
and prevents rotation of the holder. By employing a special
disc in the drum assembly, this type of assembly may be used
as a
replacement for the former style.
The improved main spring and holder assembly has been further
improved for
safety on machines above Serial number 553017.
The centrifugal governor drum gear and main spring are now
held
together by a retainer clip (Fig. 22). This prevents the
main spring from accidentally jumping out of the holder when
it is being installed or removed. The power frame has been
countersunk to provide
clearance for the retainer clip.
Installation and removal of all main springs and drums should
continue to be made with extreme caution.
Figure 21. Early Main Spring and Holder Assembly
Two types of trip links have been used on the Model Bl. One
is the solid link with pin clevis, the other uses a clevis contain-
ing a compression spring. The spring clevis was designed to
improve impression by equalizing the tripping force at various
typing speeds. This spring clevis is not used presently and may
be
replaced by-the conventional link and clevis if desired (Fig.
18) •
Two types of escapementpawl\:lracket assemblies are used on
the Model Bl. Machines of 62/5 and 14 pitch, and all deci-
9
mal tabulation models use an escapement pawl with .038" of
left to right motion. This assembly bears no identification
mark. Machines of 8, 9, 10, and 12 pitch use an escapement
pawl with .058" of motion and can be identified by a round
groove
in the front edge of the pawl tai I and spacer. The
spacer .used with this pawl has the upright lug positioned .010"
to the right. This arrangement is referred to as the "floating
pawl" and permits increased typing speed without type piling.
Increasing the length of the elongated slot in the escapement
pawl allows
the pawl to snap further to the right after being
tripped. Consequently, the carriage begins to move the pawl
back to
the left sooner. The pawl spacer lug, being further
to
the right will pick up the pawl tail earlier and be ready for
the next operation.
The floating type escapement pawl is also used on the Model B
lift
platen typewriter above Serial number 358277. The toll
bi Iler and decimal tab machines use the former non floating
style
pawl.
Main
Figure 22. Main Spring Holder
MARG1N SET
The term "margin" denotes the distance between the edge of
the paper and the typewritten material. Left and right margins
are determined by the position of the margin stops on the mar-
gin rack. Carriage travel is limited when the stops strike the
Mar{lin Set Bracket
Figure 23. Margin Set Mechanism

'margin control levert which is. located just below the margin
rack. The margin stops encircle the margin rack and contain
!eeth that mesh with those on the rack (Fig. 23). The number
of teeth per inch correspond to the pitch of the· machine.
The margin set is designed to allow the operator to reposition
the margin stops without moving her hands from the keyboard.
To change the margin, the operator must follow four steps:
position the
carriage at the existing margin; then depress the
margin set button; move the carriage to the desired position
with
the button held down; then release the button and check
the position
by operating the carriage return.
The front end
ofthe margin set key lever has a bottom lug with
an angular camming surface that contacts the carriage return'
key lock (Fig~23). The upright extension on the rear of the
key lever receives the adjustable clevis on the margin set link.
The rear of the link is attached to a lever on the margin set
shaft. The right end ofthe shoft is pivoted on the right side
frame and the left end
is pivoted on the right-hand motor
bracket. A rocker arm is attached to the left side of the shaft
and contacts a stud on the bottom
of the margin set lever.
The margin set bracket has countersunk holes where the
chamfered ends
of the margin set lever hub contact the' bracket.
The bracket is held to the inside of the rear frame by two
screws, one
of which goes through the motor bracket. Earlier
brackets did not extend down as far on the
rear frame and did
not have countersunk holes for the hub
of the set lever. Prior
to the use of the screw and stop nut, a pin and two C-clips
were used to mount the set lever on the bracket. The changes
were designed to
eliminate side play in the margin set lever.
(Operation)
When the margin set key lever is depressed, its bottom lug
cams the
key lever locking bar into a position that locks an
operations except: backspace, space bar, shift and margin
release. This protects the margin set mechanism from damage
by
carriage return or tabulation while setting margins. The
upright extension on the
key lever pulls the margin set link
forward so the lever on the margin set shaft rotates forward.
The rocker arm on
the margin set shaft moves the bottom of the
margin set lever
to the rear. The margin set lever rotates about
its fulcrum
point, and the front end of the lever is lowered.
With the
carriage at either margin, the margin set lever will
contact the margin stop and lower it farenough to disengage
it from the margin rack. With the margin. set keybuttoh held
down, the carriage may be positioned by using the space bar,
backspace, or carriage' release levers. The new position of
the carriage wi II also be the new position of the margin stop
after releasing the margihset key button.
Carriages longer than 12" require one or more center supports
attached to the margin rack to make the rack rigid. These
center supparts obstruct the travel of the margin stops. Margin
setting is therefore restricted
to an area bounded by a margin
rack
center support and the extreme left or right margin.
MARGIN RELEASE
Margin release provides tlie,operator with a means of releasing
the
carriage from the restriction of either the left or tight mar-
gin stop without moving the stops. Margin release is used to
lower the margin control lever enough to allow the margin
10
stops to pass. This permits additional carriage travel from the
position of the set margin stop to the carriage final stop, yet
retains the margin stop setting for further use.
The
margin release key button is attached to the front end of
a long key lever that extends back to the tab actuating lever
on the governor control bracket assembly
(Fig. 24). The mal'-
gin release key lever does not extend into the front guide
comb. A shoulder screw mounts the key lever to the poWer
frame and serves as its fulcrum point. The motion of the key
lever is restricted by the key lever fulcrum wire within the'
elongated slot in the key lever (Fig. 24).
Figure 24. Margin Release Key Lever
When the key button is depressed, the key lever pivots on its
fulcrum screw. The rear of the key lever contacts and raises
the margin release
eccentric, which is attached to the tab
actuating lever. The tab actuating lever raises by rotating on
its mounting
rivet. A hook extension on the top of the actu-
ating lever is positioned in a slot in the left end of the tab
lever.
The actuating lever raises the left end of the tab lever, using
the
tab lever pivot screw as a fulcrum point. The margin con-
trolleveris lowered by this operation, as it is a part of the
tab lever assembly. The margin stops may now pass over the
margin control leve.r.
Earlier machines used a different
key lever arrangement which
required more force on the
key button 0 Depression oithe key-
button raised the rear end of the margin release key lever qnd
its link. The link rotated the margin release bellcrank which
moved a push rod toward the rear (Fi g. 25). The push rod
rotated a small bellcrank mounted on
the governor control

Tab
Figure 25. Early Margin Release Key Lever
bracket. The tab actuating lever was riveted to this bellcrank
and was raised by this action. The balance of .the motion was
the same as the present style margin release.
LINE LOCK
The purpose of the Iine lock is to prevent the operator from
typing one character over another when the carriage has reach-
ed the right margin control lever. The operator receives a
warning
of the approaching right margin when the bell rings
approximately 10 spaces from the margin. When the letter
key levers lock at the margin, the operator must then decide
whether to complete or hyphenate the word being typed. To
unlock the key baard, the line lock is released by depressing
the margin release. The operator can then complete the word
or
line. If the operator has just completed a word as the ma-
chine gees into line lock, moving the carriage from the right
margin will release the machine
from the line lock position.
This
can be done with either carriage return or backspace.
Upper Line Lock Bellcrank
Figure 26. Line Lock Mechanism
11

(Operation)
The right margin stop contacts the large flat portion on the
right end
of the margin control lever (Fig. 26). The margin
control lever
is mounted to the tab lever assembly by means
of elongated slots that allows-left to i'ighf motion of the lever.
The margin stop moves the margin control leyer to the left. A
lug on the left end
of the margin control lever contacts the up-
per line lock bellcrank which is mounted by a shoulder rivet
to the tab horseshoe bracket. The upper bellcrank rotates,
pushing down
the vertical line lock link which lowers the hori-
zontal arm of the lower line lockbellcrank. The lower bell-
crank, whicb is mounted to the left side frame, rotates and
moves the push rod toward the front
of the machine. The front
end
of the push rod contacts the left end of the key lever lock-
ing bar and moves it. under the tab and letter key levers (Fig.
27)
The carriage return keylock is not moved during line lock.
This leaves carriage return unlocked, and
is done to permit
the carriage to be returned to the next writing line.
lock Bar Fulcrum Wire
paper as the typewriter is operated. The paper is guided
around the
ploten by the deflector, and held against the platen
-by the feed rolls. The feed rolls are mounted to the inner
carriage,arid will be covered in detail under "pAPER FEED".
Theinrie;carriagecontrols th¢ front. to rear position of the
platen and
is moye~ by the multiple copy control lever)Fig.
28}. This leverrotOtesa~haft, called the platen guide shaft.
This shaft includes ecceritrit.'collars that work against parts
mounted
to the outer carriage "cmd cams the entire inner car":
riage forward or backward. Th.e firsf three positions move the
carriage less than the last two, affording a finer initial
adjust-
ment. The inner carriage co~sists of the following (Fig. 29):
left
and' right platen guide plates, platen- g!Jide shaft, fel;ld
roll release camshaft, paper bai/pivot shaft and the paper
table tie-rod. Other parts on the inner c\Jrriage wi II be
c:;overed under their respective mechanisms. The_ platen_guide
plates cire mounte.d to the outer carriage in a manner thcit allows
them to move front to
rear. They are spring-loaded to the rear
to eliminate any play. The left platen guide plate has one
extra bearing point o,n the outer carriage to obtain additional
stability for the line space mechan-ism. Earlier machines used
a carriage side frame
eccentric nut as a third bearing point for
the guide
plates, and the plates were not spring loaded.
Paper Release lever
Figure 27. Une Locking Bar Eccentric Collar
The operation of margin release lowers the rrorgin control
lever
and allows it to restore to the right, due to the tension
of the tab check lever spring, and assume its rest position.
The spring load on the
key lever locking bar restores the line
lock mechanism
to its rest position. Moving the carriage to
the right a
Iso permits the margin control lever to return to its
rest position and this, in ;turn, allows the restoration of a11
line lock parts.
The
letter key levers can be locked by the key lever locking'
bar in one of two positions. When the kElY lever is in the rest
position, the locking bar moves underneath a locking lug on the
key lever, and prevents the depression of any key lever. Should
the operator have a key lever depressed as the line lock is
actuated, the locking bar wi II move over the lop of the lock-
ing lug and the key lever will be locked in the depressed po"-
sition. One piece repeat/non repeat key levers are made
without a locking lug to prevent
their being locked in the de-
pressed, or operating position'. This feature prevents possible
damage to the paper
from continued repeat action at the right
margin.
CARRIAGE AN D RAILS
The basic purpose of the carriage is to support aR.d position the
12
Figure 28. Multiple Copy Control
The vertical motion of the platen is eliminated by the platen
latches that ~otate over the top of each platen bushing and
hold the bushing down against the end
plates of the outer car-
riage {Fig. 29}., The outer carriage consists of the carriage
bed, and the two carriage end plates. These parts are welded
together to -form a bax-type carripge'construction that gives
maximum rigidity
to the carriage.
The carriage bed nas two rows of milled teeth running its full
length. These provide motion for the rotation of the staw
wheels
in the plastic truck assemblies (Fig. 30). Each truck
coritains four steel rollers that engage the carriage ways and
the rai Is to allow,free motion of the carriage to the left and
right. The truck rollersfit into holes in the truck housing.
These holes have smalt bosses
that retain the rollers and keep

Platen Retaining Plate
Figure 29. Carriage Parts
them from falling out when the truck is removed from the ma-
chine. Early truck rollers used nylon retainers that snapped
into recesses in
the truck. The ten tooth star wheeI is pinned
into
the truck. Motion of the teeth on the carriage bed rotates
the star wheel, which also meshes with similar teeth on the
rail, and the star wheel moves the truck assembly. The car-
riage moves at a ratio of 2:1 with respect to the truck assembly.
The bottom
of each carriage end plate has an extension that
strikes the carriage fina I stop, mounted underneath the front
rail, when the carriage is moved beyond the left or right mar-
gin stops. The carriage final stop may be depressed against
a spring load when carriage removal is desired. Carriage re-
moval is made possible, without disturbing rail adjustments,
as
the carriage ways and rails have milled teeth their full
length
(Fig. 31). The front and rear rails are mounted on the
power frame casting.
Starwheel meshes with teeth I_
on top of the carriage way ~
__ ~_.---- ..., ""w
(}i--~;
-~~--~-
Starwheel meshes with t8eth
on boHom
of the ra iI
Figure 30. Carriage Truck Assembly
13
Carriage motion is involved in many operations of the machine.
Typing, space bor and tabulation cause carriage motion to the
left. Carriage return,and backspace cause carriage motion to
the right. Hand carriage release can be used by the operator
to move the carriage in either direction. To do this, the
operator depresses the left or right carriage release button and
moves
the carriage whi Ie holding down on the button. The
button rotates
the carriage release lever, which is mounted
on a stud on
the carriage end plate (Fig. 28). The lever pushes
the carriage universal bar toward the rear of the machine. The
universal bar runs
the full length of the carriage and is mount-
ed to the carriage end plates. The universal bar contacts an
upright I
ug of the pawl re lease lever (Fi g. 32). The pawl
release lever
is mounted to the rear rail by an eccentric and
screw. It has a lug which extends behind the rear rail and
actuates the backspace inter lock. It has another I ug under-
neath the raiI that rests between the escapement pawl and the
escapement rack. This lug pulls the pawl from the rack when
the pawl release lever is rotated. Release of the carriage re-
lease button and restoration of all release parts to rest allows
the pawl to return to the rack.
The other parts on the carriage, such as paper feed parts, tab,
margin and escapement racks are covered under their respective
sections. The rear rai I provides the mounting for many parts
that control carriage motion and position. These will alsobe
covered under their respective mechanisms.
The number
of truck assemblies, writing line and paper size
vary with carriage length in accordance with the following
.chart.

Writing Line
Carriage Length Number
of Trucks Between Margin Writing Line Paper Size
Stops (Maximum)
12"
4
10.4"
11.25"
11"
16" 6
14.4"
15.25"
15"
20" 8
18.4"
19.25"
19"
24"
10
22.4"
23.25"
23"
30"
12
28.4"
29.25"
29"
lH Rail Support
Figure 31. Carriage and Rails
Intermediate pawl release
lever .trikes this
Escapement
engaged in
Pawi release lever at rest
Tab lever .trikes,hi.lug
Figure 32. Pawl Release Lever
PAPER FEED
The paper feed mechanism is a part of the carriage assembly.
Paper feed and paper release
are the two bosic functions of
this mechanism.
The inner carriage provides the mounting for the paper feed
mechanism
so that when the inner carriage is cammed front or
rear by the multiple copy control mechanism, the paper feed
14
and release parts will move with the platen.
The paper feed mechanism i"s made up of many parts; all of
which aid in the proper feed or release of the paper.
Paper Feed
To begin the operation, the typist places the paper against
the
rear paper table (Fig. 33). This table is a part of the car-
riage and is to the rear and above the platen. It is supported
Rear Pressure Lever
Figure 33. Paper Feed Mechanism

Rear Pressure Lever Feed
Rof.( Tension Springs Carriage Release Universal
Bar
j, ... ..".,-~ ...
Front Pressure Lever Platen
Guide Shaft
Center Support
Shaft Eccentric
Figure 34. Feed Roll Mechanism
on the paper bai I pivot shaft and the paper table tie rod. Arms
from the front paper table serve as latches to hold the rear
paper table to the tie rod shaft. As the paper is inserted into
the machine, an adjustable guide mounted on the rear paper
table serves to position the paper for its left margin position.
Next the paper contacts the rear rolled edge of the deflector
(Fig. 33). This edge guides the paper into the "V" formed by
the rear feed rolls and the platen. The bottom of the deflector
contains lugs that stradle the feed roll release cam shaft and
serve to position
the deflector. Support lugs on the rear pres-
sure levers control the distance between the deflector and the
pl~ten. Sixteen inch and longer deflectors are connected by
a rod which
is spot-welded within the rolled edge.
A single piece deflector, designed to faci Ii tate manufacture
is in all 16" machines above serial number 613547. Horizontal
and
rotational movement of the single piece deflector is pre-
vented by two formed I ugs on the rear of the deflector. These
lugs seat in undercuts on
the feed roll release cam shaft. The
former
spot-welded lug-type deflector wi II remain avai lable
for
replacement on machines prior to this change. If it is de-
sirable to con'vert to the new single piece deflector on machines
prior to this
change, it will be necessary to replace the feed
roll
release cam shaft. The new shaft is interchangable with
the former shaft.
Rotation of the platen causes the paper to be fed between the
re~r feed rolls and the platen. Feed rolls are spring loaded
against the platen and are rotated by their friction on the paper
or platen (F ig. 33). As the front edge of the paper leaves the
rear feed rolls, it is guided by the deflector unfil it moves in
between
the front feed rolls and tbe platen. Both front and
rear feed rolls now hold the paper firmly agairist the platen
and insure its rotation wifh the platen.
Feed ro II pressure is supplied by applying a twist to flat torsion
springs
(Fig. 34). The ends of these springs are mounted in
15
slots in plastic bushings which are molded to the pressure
levers. Feed ro lis mount on shafts whose ends mount in these
pressure levers. Feed roll pressure
is determined by the
amount of twist put into the spring by their adjusting screws.
The ends
of the springs attempt to rotate the plastic bushings
and pressure levers, and in this manner supply a constant
up-
ward pressure to the feed rolls. The pressure lever bushings
are mounted in holes in the feed roll cradles and the cradles
are mounted to the feed roll release cam shaft and the platen
guide shaft. Left to right motion of the cradles is restricted
by a feed roll center support on one side, and a spring clip
on the platen guide shaft on the other side. Left to right
motion
of the pressure levers is restricted by the cradle~ which
are held on the plastic bushings by spring clips.
Each feed roll is molded to a hub and two hubs are mounted
on
each feed roll shaft. This arrangement gives maximum
bearing surface for
the rotation of each feed roll. The feed
roll shaft
is mounted in "D" shaped holes in the pressure levers.
These holes
keep the shaft from rotating. The shaft has a spring
loaded plunger
at one end for ease of removal and replacement.
Feed roll hubs and rear feed roll shafts have been redesigned
to
reduce the length of the feed roll hub by approximately
1/4 inch. This change appears on machines above serial num-
ber 519557. Feed rolls have been placed in the center of the
hub (Fig. 34) and the hub assemblies are retained on the shaft
by two
adjustable clips which permit adjustment to reduce end
play of the feed rolls to a minimum. The clips are also used
to ho
Id the shaft in place in the rear pressure levers. The
front feed rolls
are sti II mounted on the shaft with the spring
plunger. It is necessary to use this shaft in order to hold the
front pressure levers in place.
The feed roll center support is mounted on the carriage bed
and helps
to position the feed roll cradle assemblies (Fig. 35).
In addition, the center support provides rigid support for the
feed roll release cam shaft and the center platen guide shaft

eccentric. Sixteen inch and longer machines use the center
support as a mounting for the margin rack center support.
As the paper rotates further, it is guided upward by th~ front
extensions on the
deflector and the front paper scale (Fig. 33).
Margin Rack Cen/er. Support
Feed Roll Release Shaft
Figure 35. Feed Roll Center Support
The front paper scale is mounted on the platen guide shaft.and
is spring loaded toward the platen by a coi I spring mounted
around this
shaft. The scale contains calibrations which cor-
respond to the pitch of the machine.
Dust Cover Adiusting Screw
Figure 36. Line Gage Card Holders
Above the front scale and immediately below the writing line
• are the line gage card holders (Fig. 36). These assist in hold-
ing the paper, and more "specifically, cards to the platen in
the writing area. The line gage card holders are mounted to
the front rail dust cover, which in turn is mounted to the front
'rail. The card holders also have a scale calibrated to the
.
'pitch of the machine. Later machines uSe an offset line gage
6ard holder for the purpose
of reducing the possibility of under-
printi ng on the paper.
The two screws that mount the card holders also mount the
16
'indicator pointer (Fig. 36) • This pointer is used .to indicate
the position of the carriage in relation to the type guide. The
operator reads the front scale ,calibration indicated by the
pointer
to check the carriage position. '
Above
the writing line the paper is engElged by two or more
rubber rollers which
are m<:>lmted on the paper boil (Fig. 37).
,These rollers hold the paper to the platen above the writing
nn~so as to reduce the possibility of over printing on the
paper. The rollers also·feedthe pop-er away from the operator
so the writing line is plain Iy visible.
Bail Shaft
Figure 37. Paper Bail
The 'paper boil has three positions which are; above tbe plate
in the raised position, in front of the platen in the forward
position, and against the pla'ten
in the operating position.
These positions
are made possible by the use of paper baiI cam
levers
to which the coiled bai I springs supply pressure • The
bail arms
are mounted to the paper bail pivot shaft, and are
free to 'rotate about this mounting. The pivot shaft is als9
free to rotate. A steeI ro Iler is mounted on the bottom of each
bai I arm and receives pressure from the cam lever. This pres-
sure forces the rear end of the bai I arm up and the frc;mt end,
'including the bail rolls, down. The bail rolls are free to
rotate about the baiJ shaft, but contain a spring clip that re-
stricts their laterial motion, unless they are pushed with enough
force
to over come the resistance of these spring clips. When
the bai I
is moved from the forward to the operating position,
a plastic roller mounted on
each bai I arm rides over chrome
plated strips of metal, called bumpers, which are mounted on
each carriage end cover. These insure easy operation and
help the bail rolls pull the paper against
the platen in the area
of the writing line. .
Next the paper passes in front ofthe front paper table (Fig.
33). Its purpose is to prevent refeeding of the copy paper and
can be used as an erasing platform.
The front paper
table contains two scales; the top is cal ibrated
in inches, the bottom corresponds to the pitch of the machine. (
Thrs table provides an easy method of checking machine pitch.
Simply count the number of calibrations on the bottom scale in
one inch on the top scale. The sum equals the pitch of the
machine.