Manual / Guide · 1941
Description of Operation of No 15 Teletypewriter Bell System Practices Section AB84 139 1941
Description of Operation of No. 15 Teletypewriter
Manual / Guide · 1941
Description of Operation of No. 15 Teletypewriter
BELL SYSTEM PRACTICES SECTION AB8,.139 Transmission Engineering and Data Issue 1, November, 191 Telegraph Stations and Loops AT&TCo Standard DESCRIPTION OF OPERATION OF NO. 15 TELETYPEWRITER This section describes the operation of INDEX the No. 15 Teletypewriter. It has been issued principally for use in training Bell System DESCRIPTION OF THE MODEL 15 teletypewriter repairmen. It is reproduced from material originally prepared for other TYPEBAR PAGE PRINTER purposes with such modifications as seem de- sirable to facilitate its use in conjunction PAGE with other Bell System practices in the pro- posed training work. The basic operating GHNERAL « eo see HH Ee eee 2 principles are described but no attempt has been made to include recent improvements and Keyboard Transmitter ........es 2 changes. Signalling Code . 2... es ee eee 2 SINGLE -POUBLE LINE FEED LEVER TWEBAR CAKKIBEE MANUAL CARKIAGE RETUEN LOCK BAR DAEHEOT LEVER ~ COLE SRF a “5 : ER | ts & SELL CANS “er mags Pe Sil 4 e Pi ety BOLUSTING SHREW e = SET MT VANES Sab SMO -KECEWE BRLBK MECMEMESS KEVEOMRD ULCETRATION 2 This section contains material prepared by the Teletype Corporation and it is used with their permission. Printed in U. S. A. Page 1 SECTION AB&,.139 INDEX (Cont'd) PAGE TYPING UNIT . 2. we we ee ve ee eee hy Carriage Return .... ee ee 15 Figure Shift and Letter shift aoe 16 Functions .. oo HF a we Wh Keyboard Locking Mechand sm co ee we ew 19 Line Feed Function .s. «ss e686 18 Locking Vam «ss wee www 8 Hw 7 Locking Function Lever ... 6 se 2 » 8 Main Shaft Assembly .... s+ eee 5 Main Shaft Clutch Throwout Lever... 8 Mergin Sigmeal Bell « «6 8 #6 * w 8 12 Motor Stop Function . 1... «se eee 19 Praimtime « s+ © we ow Ew we HR HS 8 Hibbowm Feeding se os *©s « * # «© @ 12 Ribbon Lockout . 1... + + + eee ee 1h Ribbon Oscillation .. ......e ee 13 Ribbon Reverse . «+. + 2 + eee eee 13 Selecting Unit . 2. 1 2s. se eee een 5 Signal Bell Function-. . . » 6 « « « « 17 Sixth Vane . ov ee we eo ww sees 16 OPAC % 10 2 exe wo ew i we 10 Spacing Function . 2. 6s we 2 ee 6 17 Unshift on Space Function .....-. 17 MOTOR SPEED CONTROL - MOTOR GOVERNOR .. al BASE UNIT . » we ew ee ew wove vene 22 SYNCHRONISM 22 ORIENTATION . «6 6 6 © ew ee ww ew ww 23 LINE TEST KEY 2. 6 1 6 0 6 we we eo we ww eh 2h, LINE RELAY 2... 1 ee ee eee vv ee GENERAL The Now 15 Teletypewriter is a machine designed for interchanging messages between two or more points. A sending-receiving ma- chine consists of a keyboard transmitting unit, base, typing unit, and cover (Illus. 2), The keyboard transmitting unit is used to send electrical impulses of the five unit code to the receiving mechanism of the typing unit at any station. These received signals will cause the typing unit to type a copy of the message sent by the keyboard operator. Signalling Code The signalling code used to transmit characters is the "Start-stop," five unit code which consists of five selecting impulses used in various combinations of current and no- current intervals. Each group of five select- ing impulses is preceded by a start impulse and followed by a stop impulse used to main- tain synchronism between all stations on the circuit. Impulses which operate the selector magnets are known ‘as marking and those which do not are known as spacing. Fig. 1 shows graphically the code used. Page 2 CHARACTER L/NE SENT SIGNALS | F747 4 tie Q IMPULSES ® 12ZI745% RN OO FON + @ Aw HD 1 YODSe ON5E N NAS VNONHAHOVOV>S TH RCN TOA AMOAVVA LOWER CH SE ie) n wR 5 7 j 2 Oo / (Cn ¢ Cl _ LIVE FEEO (__ 1 SPACE =(__ CAR RET, Ce ‘icveésS Levees CE | ) SPACING (/MPULSES = MARKING IMPULSES Fig. 1 Keyboard Transmitter The keyboard (Illus. 3) consists of a set of keys, keylevers, a bank of sending con- tact springs; operating cams, clutch and gear. This gear engages with the transmitting shaft driving gear (Illus. )). The sending cams are normally held stationary because the clutches on the driving shaft are held apart by the clutch throwout lever. When a key is Ce a Od - a depressed the driven member of the clutch is per-. mitted to move into mesh with the driving mem- ber causing the cam sleeve assembly to revolve. At the end of the revolution the driven member of the clutch is disengaged by the clutch throwout lever and the cams brought to a stop until the next key is depressed (Fig. 3). Beneath the keylevers are five selector bars and a universal bar extending across the width of the keyboard. The selector bars are provided with saw tooth shaped notches as shown in Fig. 2 according to the requirements of the signalling code. These bars rest on rollers and are guided at each end so that they may be easily moved endwise. When a key is depressed the keylever strikes the slanting sides of these notches moving the bars either to the right or left depending upon whether the impulses corresponding to the bars are to be spacing or marking impulses. The universal bar which is connected to the trip off pawl controlling the starting and stopping of the sending cams is pivoted at its two ends in such a way that the depressing of any key moves it downward to actuate the clutch throwout lever. Thus, whenever a key is depressed the selector bars are set and the universal bar is moved down permitting the sending cams to start rotating (Fig. 3). SECTION AB&,.139 Each selector bar engages a vertical locking lever at its right hand extremity and positions it to correspond with the signal im- pulses to be transmitted (Fig. 2). Each lock- ing lever controls the motion of a contact lever by either allowing the contact lever to close its contact when the cams revolve or re~ stricting the motion of the contact lever. If the upper end of the locking lever is po- sitioned to the left corresponding toa spac- ing impulse, it engages the contact lever and prevents it from rising into the indent of the cam as it rotates, thus holding the circuit open for that impulse (Fig. 2-A). Ifthe lock- ing lever is positioned to the right corre- sponding toa marking impulse it does not inter- fere with the movement of the contact lever (Fig. 2-B). Then as the cam revolves the cone tact lever rides on the cam surface and rises into an indent thereby allowing its contact to close, sending out a marking impulse. As the cams rotate the impulses, either marking or Spacing, are transmitted in succession. The start-stop cam controls anadditional contact lever which in turn actuates the start-stop contacts (Fig. 3). These contacts are opened at the beginning of each revolution. of the cam shaft to transmit the start impulse LUTCH CLUTCH THROWOUT LEVER LOK LOOP CHE LOCK LOOP START -$TLP Chl LOCKING LEVERS SO) SLEEVE MESEPILLE MW TERMED E PR. CINE TEST KEY THIO OF PAWL COI?” LEVERS REL, SYCE ROO LNT RN ES wereenees AEVBORD MLLOETRET VOW F Page 3 SECTION AB&).159 CONTE CAM COMAET LEVER- | OAT PES emis LAHING LEVER. KEY LEVER goes PLAAANNANR AALANMS AL LOCKING LEVER. KEY LEVER CONTACT LEVE#- CONTACT SPRINGS (A) cere wae —/" Fige 2 LOCK LOOP’ CIPI STAKT-STOP CALA CAPA SLEEVE ASSE/IBLY- =" CLOICA! THROW-OW7 LEVER TRIP OFF PAW ECCENTRIC no Mi Ute mg ee i THROW -OUT CAM OE Gotan ee LEVER? SELECTOR BARS OMWERSHAL GAR / TRIP OF PAUL SERCE PEPEBT ROD KEY —_ —, KEYLEVER = (| 2 j | Re SPBCE KEVLEVER ini (SEE ALUSTRATION 3,) Fig. 3 (spacing) and remain open during the transmis- sionofthe five impulses, After the fifth im- pulse has been transmitted, the start-stop con- tacts will again close sending the stop im- pulse (marking) to the line. These contacts will remain closed until the next keylever is depressed. At the end of the revolution the clutch driven member is cammed out of mesh with the driving member and prevents the cams from rotating further until the next key is de- pressed. The lock loop which is raised by the lock loop cam at the end of each revolution to allow the new combination to be set up is used while in its down position to prevent a change in the selection set up (Illus. 3). This is done by holding the locking levers in their set positions while the signals are being sent out. This arrangement also makes it impossi- ble to depress another key until the signal for the previous character has been transmitted. The keyboard is equipped with aspace re- peat device which permits the transmission of continuous spaces. (Illus. 3.) When the space keylever is depressed, the space repeat rod attached to the keylever extension will move the clutch lever pawl forward in turn holding the .clutch throwout lever out of Page ly engagement with the projection on the driven clutch. Thus the transmitter cam sleeve will be permitted to revolve continuously wntil the space keylever is released. TYPING UNIT The typebar carriage of the Model 15 typ- ing unit consists of typebars similar to those of a typewriter together with other associated parts. The typebars are mechanically thrown against a platen causing letters tobe printed. The typebar to be selected is determined by the setting of five code bars which are actu- ated by line signals through the medium of the selector mechanism. The code bars are so ar- ranged that the notches on their upper sides will be lined up permitting a selected pullbar to move down into the path of the pullbar bail. This bail moves the pullbar forward causing the typebar to which it is connected to strike the platen, JIilustration 2 shows the typing unit moumted on the base with a keyboard. The various functions; line feed, space, carriage return, figure shift, letter shift, etc. are also accomplished mechanically. A FUNCTION BAIL CAM ~~ PRINTING bhi CAM SELECTAR CAM SLELVE LOCKING CAM sree sey FRICTION CLUTCH PLATE MEMBERS MAIN SHEET BEARING MAIN SARE CLUTCH — SPRING ESCAPEMENT RATCHET. MPIM SHAFT SPSCING GEAR SECTION AB&,.139 SPEICING STOP SLEEVE — FRICTION OSE | pm a Ge YW PLUG MAIN SHAFT BEAGING MAIN SHAFT TRANSHUTTING SHAFT DRIVING GAR “IAIN SHRFT ASSEMBLY VALUSTEATION F motor drives the main shaft assembly of the typing unit which supplies power to all mechan- ically operated parts. Main Shaft Assembly (Illus. |). The main shaft gear is located near the right end of the shaft and meshes with the mo- tor pinion. Thus it may be seen that the main shaft will be caused to rotate continuously during the period the printer is in operation. The main shaft also operates the keyboard cam shaft through the medium of the transmitting shaft driving gear. The main shaft spacing gear meshes with the spacing shaft gear to provide the spacing action at the required time (Illus. 8). The spacing escapement ratchet, sleeve and fric- tion discs are associated with the spacing mechanism and are described under "Spacing." The function bail cam and the printing bail cam operate their respective bails. The main shaft clutch is used in conjunction with the selector to provide power to operate the print- ing and function bails immediately after the selection has been completed. The selector cam sleeve is fitted over the left end of the main shaft and is driven through the medium of a friction clutch. Selecting Unit The purpose of the selecting wit is to receive the signals from the transmitting station, distributing them mechanically, there-~ by setting up various combinations onthe vanes. These combinations will determine the charac- ter to be printed or the function to be oper~ ated. The selector mechanism is controlled by the magnet which receives the code impulse from the line, Normally the armature of this magnet is pulled up and the stop arm. is against the stop lever which in turn isheld by the trip latch. Because the stop arm which is apart of the selector cam sleeve is engaged with the stop lever, the cam sleeve is pre- vented from revolving (Fig. l). When the start impulse which is spacing (no current) is received the armature is reo leased and pulled away from the magnet pole pieces by the armature spring. This will move the trip latch out of engagement with the stop lever thereby releasing the stop arm allowing the cam sleeve to revolve with the main shaft. Each vane is operated by a selector cam through a "T" lever, a sword andaselector le- ver (Fig. 5). For instance, suppose that the code for the letter "E" is received, Upon the reception of the start impulse (a no current impulse), the armature moves away from the mag~ net, imparting motion first to the trip latch plunger (Fig. 11), which in turn causes the bell crank to move the trip latch out of en- gagement with the stop lever releasing the stop arm as explained previously, The selec-= tor cams start to revolve and the number 1 se- lector cam engages number 1 selector lever, Page 5 ADJUSTING SCREW BRACKET ECCENTRIC ARMATURE EXTENSION - SworDs (5) BRACKET L1VK ARMATURE BRACKET SCREWS LOCKING WEDGE NUT ARMATURE BRACKET MOTOR STOP PAWL LATCH SPACING STOP SCREW MARKING $7OP NUT SELECTOR "T" LEVERS satiaiilaiais is STOP POST MAGNET CORE INNER MOTOR STOP PAWL MAGNET OUTER MOTOR STOP PAWL MOTOR STOP RELEASE LEVER ECCENTRIC MAGNET BRACKET ‘(MAGNET BRACKET MOUNTING SCREWS MOTOR STOP LEVER BACK STOP SCREW PIVOT SCREW MOTOR STOP LEVER TRIP OFF ECCENTRIC SCREW RANGE FINDER ASSEMBLY TRIP LATCH PLUNGER STOP LEVER PLATE MOTOR STOP RELEASE LEVER SELECTOR UNIT ILLUSTRATION-S THUMB SCREW STOP LEVER ECCENTRIC SCREW TRIP OFF. SELECTOR MAGNET LCCENTRIE SCREW BELL CRANK BEMATURE EXTENSION CLAMPING PLATE -— = Mn sitar TRIP LATCH ~~ SELECTOR LEVERS if STOP ARM CLAMPING SCREW ff STOP LévER N N STOP LEVER RANGE SCALE ECCENTRIC SCREW (SEE /LLUSTERTION $) Fig. Page 6 we, when the first impulse of the letter "E" (Marke ing or current impulse) has been received by the magnets from the line. The magnet arma~ ture is therefore pulled up, bringing the up= per end of the armature extension up into the path of the upper sword arm. When the number 1 cam passes the number 1 selector lever, this lever is rotated cowmterclockwise, carrying with it the sword, which strikes the upper end of the armature extension and is in turn ro- tated clockwise about its pivot, point A. This positions the sword so that when the nun- ber 1 cam clears the selector lever, the selec- tor lever spring moves the sword against the "T" lever and brings the front edge of the num- ber 1 vane down, As no current is received while number 2, 3, l; and 5 cams are passing their selector levers, the magnet armature is released and the armature extension moves down so that the lower end of the armature exten- sion is in the path of the lower sword arm (Fig. 5). As the number 2, 3, and 5 cams pass the number 2, 3, ], and 5 selector levers the number 2, 3, and 5 vanes are moved so thet the front edges are up. With the front edges of the vanes. in the upper position the corresponding code bars will be moved to the right or umoperated position through the medium of the bell cranks (Illus. 2). With the LOD MME i Ss ARDAAT URE SELECTOR MAGNE7- SELECTOR CASA SNGK?P AKAM E ——-___—_—-—~. BREMATURE EXTENSION LOCKING CAP4- LOCKING LEVER SECTION ABS).139 front edges of the vanes in the lower position the corresponding code bars will be moved to the left or operated position. - With the mm- ber 1 code bar to the left and number 2, 3, and 5 code bars to the right, there is a notch in each code bar opposite the "E" pullbar, The sixth cam releases the main shaft clutch allowing the printing and function bail to make one complete revolution (Fig. 8). The printing bail cam will permit the printing bail to be pulled forward by its spring. The "E" pullbar will be pulled down by its spring into the path set up by the code bars and the pullbar bail, actuated by the printing bail, will carry the pullbar forward causing the type bar to strike the platen printing the let- ter "E" (Fig. 9). Locking Cam The locking cam has five low and five high portions on its periphery against which the locking lever is held by its spring (Fig. 6). During that part of each impulse when the swords are set by striking against the arma- ture extension (at the time the peak of any se-~ lector cam is operating the corresponding se= lector lever) a low portion of the locking cam is opposite the locking lever. The armature Yow i “LEER LOCKING WEDGE VONE T LEVER SWORD AQEKING LEVER SPRING (SEE ULUSTRATION 5) Fig. 6 Page 7 SECTION ABG4.139 will now be held firmly in position by the "U" shaped extension of the locking lever engaging the locking wedge on the armature extension. When the locking lever is riding on the high portion of the locking cam the locking lever extension will be held away from the locking wedge and the armature will be free to move in response to the next impulse. Locking Function Lever It is obvious that the vanes are held in their selected positions until the printing of the character has taken place. This is accom- plished by means of the locking function lever. The locking function lever is the first on the right of the function levers, which are lo- cated immediately behind the vanes (Fige 7). When the printing bail is inits rear position, the function lever bail, mounted on the print- ing bail casting, is holding the locking func- tion lever away from the vanes. When the printing bail is permitted to move forward, the function lever bail roller moves down, al- lowing the function lever spring to pull the lever against the rear edges of the vanes. The locking function lever will engage each vane, whether its rear edge be raised by a marking impulse or brought down by a spacing ‘impulse, locking the vanes in their selected positions. ; The operation of the remaining function levers is dealt with under "Functions." Main Shaft Clutch Throwout Lever As previously described, the sixth cam on the selector cam sleeve releases the main shaft clutch allowing the printing and func- tion bail cams to make one complete revolution (Fig. 8). At the end of each revolution of the printing and function bail cams the clutch stop arm engages with the projection on the driven clutch member and cams it out of mesh with ‘the driving clutch member. Immediately after the fifth impulse has been received the peak of the sixth cam strikes the clutch throwout lever cam arm moving the lever stop arm out of engagement with the projection on the driven olutch member. This will permit the spring tomove the driven clutch member in- to mesh with the driving member. Thus it may be seen that immediately after the completion of the selection of any character or function the printing and function bail cams will be permitted to revolve one revolution which will effect the printing of that character or the operation of that function. From the forego- ing it may be seen that any character,or func-~ tion may be selected while the printing of the previous selection is taking place. Printing The printing bail operating arm is mounted on the bail mounting shaft on which is also mounted the printing bail, function bail and spacing escapement pawls (Illus. 9). The printing bail spring attached to the right- hand end of the printing bail casting holds the printing bail against the upper end of the operating bail arm and the operating arm roll- er against the printing bail cam on the main shaft. Thus it will be seen that the printing bail cam will determine the position of the printing bail at all times (Fig. 9). The actual printing of any character is not caused directly by the printing bail, but by the pullbar bail which it controls. The pullbar bail is attached to the pullbar bail plunger on the lower surface of which is at- tached the plunger roller (Illus. 6). This roller (when the typebar carriage is in place) is located between the printing bail blades (Fig. 9). This arrangement will permit the carriage to move from left to right and also allow the pullbar bail to be moved backward and forward by the printing bail regardless of the position of the typebar carriage. At the end of each revolution of the printing bail cam, the printing bail operating arm roller will be on the high portion of its cam (Fig. 9 & Illus. 9). The printing bail will be in its rearmost position, carried there against the tension of its spring. FUNCTION LEVER Ehlll ROLLER FUNCTION LEVER Bb. = raze) VANES oJ ee KERR ME - pm LOCKING FUNCTION LEVER SPRING LOCKING FUNCTION LEVER Fig. 7 Page 8 SECTION ABG4.139 PLUNGER ROLLER FUL‘ EAR G4 PLLMNGER IPHEING KACK- LLET PLLNGER AON FEED LEVER LOOP LMI RIEBLW FELD PAM Caer SE : aur KIEEON REVERIE SAE MEBON FEED RATCHET — VERTICAL RIBBLW FEED SHIFT i SMa TOES KUBBON REVERSE PAWL SEVEL GEAR } + aac IUPPLRT RULER aig CHRKIIGE GLE SCREW be KN KMS Ne MIEBCW FELD $REET GEAR - 4IBEELW FLED SHEE T- SOIT VEW TKPEBAR CIRKIIGE MULUSTKATION 6 ORVEN CLUTCH MEMBER ~~ fT INE CLUTCH MEMBER SRWWG BAM CBP / SINT CAM FR 55 GAY \ Eaves F SELECTOR CANES I —~— G4 AY LIE THROW UT LEVER HA} CLUTCH STOP AEM td U FUNCTION BAU cat ™ LOWEN MEMBER COLLAR THROWOUT LEVER SPRING KER. YEW (SEE ULUSTRATION 4) Fig. & SECTION AB84.139 As the printing bail cam revolves, the roller on the printing bail dperating arm will move against the low portion of the cam. The printing bail will follow the upper end of the operating arm, being pulled forward by its spring, andwill move the pullbar bail forward. The forward motion of the pullbar bail will first allow all of the pullbars to be pulled down against the code bars by their respective springs, the selected pullbar being pulled down further than the rest, into the path set up for it in the code bars. As the pullbar bail continues on its forward stroke, it will engace the notch in the selected pullbar only, (the remaining ones being too high for their notches to engage), and carry the pullbar for- ward, throwing the typebar which is geared to it against the platen printing the character. Fig. 9 shows across-section of the typing unit. The operating arm roller will again ride up onto the high portion of the printing bail cam as it completes its revolution. Thus the operating arm brings the printing bail back to its rearmost position and in turn the pullbar bail which is engaged in it. When the pullbar bail is in its rear position all of the pull- bars are moved by it sufficiently high to PEPER STERGATEVER REL ORKIACE SOPOT KELLER OMROL RETRV SPRING DEUIF ss. 1G ~ i SPANE en i . s SENG aN * SALNG SHAFT MAW BHAET GEAR. EE FRONT NG BOLE CHIRP ane oe | SENG SHIFT GEAR ~~ ~~~ FI CBREBGE RETURN CLUTEH ae CHRRISEE RETURW CPERINE LEVER. CRMEE RETURN CLITA, FORK. g MESET AAR Sf CARING RETURN LATCH BAR “Ee CARRIAGE RETURN FUNCTION LEVER. Pase 10 clear the code bars so that they are free to move in either direction. The combination for the succeeding letter then takes its place in the code bars and the printing operation is re- peated as described in the foregoing. Spacing On the Model 15 Printer the typebar car- riage is moved to accomplish the spacing. The typebar carriage is supported on two tracks. The upper track is arectangular rod and is lo- cated to the rear. The lower track is acircu- lar rod and is located above the vanes (Fig. 9 & Illus. 7). The typebar carriage is moved by the spacing gear which ismeshed with the spac- ing rack and is facilitated by three carriage support rollers, two of which operate on the front track and one on the rear track. The front track is slotted throughout its length, so that the heads of two carriage guide screws located at either side of the carriage casting, will be guided therein (Illus. 6). The spacing rack is mounted on the rear of the typebar carriage casting and meshes with the spacing gear which-is fastened to the upper end of the spacing shaft (Illus. 8). SLATE FRESE UKE ROULLRE RIEEEN $PQ0L REAR CARUUSGE JHEK TYPE BSR SEGMENT TIL SIRE 4 FLL SAR PULL BAR SM PLUNGER [ee LA pw CARKISGE SUBRT ROLLER OLE GHCS 7 GUIDE SCKEW FRONT CARRIAGE TRACK f y BLLL HANKS L St YES Mie: Nt PLUNGER ROLLER Mt AMTNG GAUL CPLAATWE AY wo] (AWN LEVER GAUL ENING BALL UL MULTI SET SUNCTIONW Bf The spacing shaft gear is located at the lower end of the spacing shaft and meshes with the main shaft spacing gear. The lower half of the carriage return clutch is fastened to the spacing shaft (Fig. 9). ‘The upper half of the clutch forms a sleeve on the spacing shaft ta. which the spacing shaft gear is attached. The carriage return clutch members are in engage~ ment at all times except when the carriage is returning from the end of a line, The func- tion of this clutch is described wnder "Car- riage Return." The main shaft spacing gear is a part of the sleeve of a friction clutch assembly. Lt consists of the spacing ball bearing screwed to the shaft, a spacing escapement ratchet, a friction dise and felt washer, a spacing stop sleeve anda clutch spring (Illus. )). ‘the main shaft spacing gear will revolve with the main shaft unless stopped by holding either the spacing stop sleeve or the spacing escape- ment ratchet. SPACING STOP LEVER SECTION ABAI,.139 When the typebar carriage reaches the end of ite travel at the right end of the printer, theright margin adjusting screw (Figg 10-4) moves the spacing stop lever into the path of a projection on the spacing stop sleeve. This prevents spacing at the end of the carriage travel, The spacing escapement ratchet is regu- lated by the front and rear escapement pawls which are mounted on the bail mounting shaft, With the printing bail in its rear position, the rear escapement pawl is engaged in one of the teeth on the spacing escapement ratchet, holding the spacing gear sleeve (Fig. 10-B). As the printing bail starts to move forward the operating arm strikes the lower end of the rear pawl, moving it out of engagement with the tooth on the escapement ratchet. At the same time the front escapement pawl moves down against the escapement ratchet into the path of another tooth which it will engage after having traveled one-sixth of a space, The printing operation then takes place. Near the HIGHT MBMGIN BOLUSTING SCREW ——ARINTINS BIL EAU MOUNTING SET SPE PON KER MAIN SHAFT SPRING ESCHPEYIENT RETOMET SPICE WL -FRONT SPINS STOP SLEEVE FUNCTION BAU CLERSTING AR (SEE ULUSTRRTION 8) (A) @) Fige 10 BELL HEME. SPRING —- PRG BELL MARGIN BELL PAL MARAN BELL CALA SHAFT SELL ABM (SEE uLusTRATIONE) Fige ll Page ll SECTION AB8).139 AIEEBON REVERGE ARPA TVA SNAF- TYPE BAR SLGPOENT CMRKIAGE SUPPL ROLLER KIEBON LOKCLT BIR LABCING KACK- MIEEON $F OCOULF RUGELN SHLD KEEN OLLIE MOT LEVER ROLLER SBEIW LET LEVER BABCKET SEAWGED ROLLER REAR VE TVPLEBR CARRIAGE MLOSTRAITEW 7 end of the return stroke of the printing bail, the escapement pawl operating arm lifts the front escapement pawl out of engagement with» the escapement ratchet and at the same time the rear pawl moves against the ratchet. This will allow the spacing gear to revolve far enough to complete the remaining portion of the space at the end ofwhich time the rear escape- ment pawl will engage a tooth on the ratchet. Margin Signal Bell Before the typebar carriage reaches the end of its travel, it operates the margin bell RIBBON FEED MVER —-—. RBEDW FEED PHBL % RIBBON FEED RET CHET as awarning to the operator that the end of the line is near (Fig. 11 & Tllus. 8). The margin bell pawl on the typebar carriage will depress the margin bell cam, tipping it, mov- ing the bell hammer away from the bell against the tension of its spring. When the typebar carriage bell pawl has been spaced beyond the cam, the bell hammer will be released and its spring will pull the hammer against the bell. Ribbon Feeding The end of the ribbon feed lever engages with the notched extension on the pullbar bail ——PULL BAR BOUL PLLWBER _- RIBBON FELD RACHET 6b | -OTENT MIBBON FELD SHAFT EAR = KISBON FEED SHAFT VERTICAL AUBEON -ELD SFT LVEL GEAR (SEE ULUSTRATION €.) Fig. 12 Page 12 SECTION AB&l,.139 MARGIN BELL fA ibe APRKICE SETCRN LEME LK VMWEG KBCK LET LETENT SYRUNG GEAR NARGN BLLL YY SHED MARGIN SELL ah SM MOUNTING Shi “WW SHOES GEAR MAIN SHAEP SCMWVG STEP $b bb LE VERTVCML SPALIVG SHAF, CORKIAGE RETURN OOLRATING LEVER LEN M BhLL iw Se REM LICHENS KEES Fpl ph els ine FEED LEVER Mise LILLE PUY BAP LINE FELD PLS BR LRN G SHEET GLB SUE, NS KEAR VWEW TENG LMT MULUETKATIN 8 plunger (Fig. 12). The ribbon feed pawl, which actuates the feed ratchet, is attached to the ribbon feed lever. With each operation of the pullbar bail plunger the ribbon feed ratchet and the ribbon feed ratchet gear, which is attached to a common shaft, is ad- vanced one tooth. This motion is carried through a train of gears and shafts, causing one of the ribbon spools to be revolved. Ribbon Reverse Assuming that the ribbon is being wound on the right-hand spool and is almost unwound from the left-hand spool, an eyelet which is fastened to the ribbon will engage and move the left-hand ribbon reverse arm. This arm moves the left-hand ribbon reverse pawl into KUEBON REVERSE SHAE SLVEL CEA VERTICAL RIBBON FEED SHRED the path of the ribbon reverse bail (Fig. 13). As the bail moves toward the rear it engages the pawl, moving the ribbon feed shaft to the left. This will disengage the right-hand rib- bon feed shaft gears and engage the left-hand gears. The ribbon will then be wound on the left-hand spool. The reversing operation takes place ina similar manner on the right side of the assembly when the eyelet near the right end of the ribbon engages with the right. hand ribbon reverse arm. Ribbon Oscillation So as not to obscure the printing, the ribbon is moved below the printing line after each character has been printed, This is ac- complished by the ribbon oscillator which is AIG EBON REVERSE AO ———KYEBON -LED SHAE KIEBON REVERSE (Yb- — MUEBRY REVERSE eit (SEE ULUETOBMIONV 6.) Fig. 14 rage 13 SECTION AB8),.139 actuated by the movement of the pullbar bail plunger (Fig. ly). Normally the ribbon is held below the printing line by the pullbar bail plunger when in its rear position. The forward movement of the pullbar bail plunger will permit the oscillator spiral spring to move theribbon shield upward carrying the rib- bon into the path of the typebars. The height to which the ribbon oscilla- tor will raise the ribbon is determined by the position of the shift lever roller. Both the oscillator and the extension are pivoted on the ribbon shift lever. The shift lever spring holds the shift lever roller against the slide bar, which is mounted on the platen assembly (Illus. 9). When the platen shifts to the "Figures" position the shift lever roller moves up with the slide bar and allows the shift lever spring to pull the ribbon oscilla- tor assembly and ribbon to the higher printing line. Ribbon Lockout The ribbon lockout bar is provided for the purpose of locking the ribbon below the printing line when stencils are being made (Illus. 7). When the ribbon lockout bar is PAPER FINGERS — PLATEN moved inward manually, it engages the oscilla. tor extension, holding the oscillator assembly in the lower position, with the ribbon below the printing line. Functions The operations of functions is accom- plished through the medium of function levers. When the printing bail is in its rear or nor- mal position, the function lever bail, which is attached to the printing bail, holds the function levers away from the vanes. As the printing bail moves forward, the function lever bail roller will move down off the high portions of the function lever rear arms, per- mitting the function lever springs to pull their respective levers against the vanes. The forward arms of the function levers are notched so that when a function combination is set up onthe vanes the selected function lever will move forward farther than the other function levers (Fig. 15). When in the selected position, the car- riage return, line feed, figures, letters, bell and motor stop function levers will be in the path of one of the blocking extensions on the function lever bail (Fig. 15). This will prevent the printing bail from moving forward OETENT RATCHET PAPER FINGER SHAFT STOPARM FRICTION ASSEMBLY SET SCREWS SAVER FINGER SHAFT SPRING HA: LINE FEED DETENT LEVER PLATEN BALANCE SPRING CARRIAGE RETURN SPRING DRUM OKAW STRAP PRINTING BAIL DASHPOT LEVER SPRING SPACING ESCAPEMENT PAWL OPERATING ARM PRINTING BAIL OPERATING ARM “i, MOUNTING SCREWS VANES STOP BRACKET UPPER ADJUSTING SCREW SEND ~ RECEIVE RESET LEVER MOTOR STOP. FUNCTION LEVER RESET LEVER LOWER ——— an ADJUSTING SCREW BLANK FUNCTION LEVER EXTENSION ~T "LEVER LEVER EXTENSION INTERMEDIATE LEVER MARGIN BELL - HAMMER STOP FOST SSL/0E BAR MARGIN BELL HAMMER SPRING MARGIN BELL CAM SPACING STOPLEVER BRACKET PRINTING BAIL BLADES PRINTING BAIL SPRING FUNCTION BAIL MAIN SHAFT BEARING BRACKET SCREWS BAI MOUNTING SHAFT FUNCTION LEVER GAIL FRONT VIEW - TYPING UNIT MLLUSTRATION 2 Page 1h far enough to allow the typebar carriage to space, However, when the locking, universal, space or blank function lever is selected, the function lever bail will not be blocked inas- much as their operation depends upon a com- plete movement of the printing bail. The function bail, mounted on the bail mounting shaft, is used to operate some of the functions and is actuated by the function bail cam (Fig. 15). The function bail spring holds the function bail cam roller against the cam at all times. After the printing bail and the function lever bail move forward sufficiently far to release the function levers, the func- tion bail roller starts to ride up the high part of its cam. This moves the function bail blade toward the rear, engaging and operating any function pushbar that may have been moved in its path by a selected function lever. The function bail roller will then ride down to the low portion of the function bail cam, the DUET LEVER? MOOLL LER KUEBOW SMUT LEVER MOT LEVER SPRING KUEBLN SHUT LEVER BUA CHE HOLLER SCL 4ULL BAR BAM PLUMOER- SECTION AB&,,139) bail blade returning to its forward position in readiness for the next function, Carriage Return When the carriage return function lever (second from the right) moves into engagement with the vanes, the function lever extension moves the carriage return latch bar upward out of engagement with its latch, This releases the carriage return operating lever, which ace tuated by its spring moves the carriage return clutch fork upward, disengaging the upper car~ riage return clutch member from the lower mem= ber. The spacing shaft is then free to turn in its sleeve so that the typebar carriage may be pulled back to its extreme left-hand posi- tion by the carriage return spring (within the carriage return drum) through the medium of the draw strap (Illus. 9). The notch on the reset bar will then be engaged by the function bail and moved to the rear, As the reset bar KIEEOW SHULD SLICE BAR KUBELY O5CULLATOR EXTENSION LEFT PLUNGER AR/A VLUNCER KOLLER (SEE ULUSTERTION 72) PRINTING GAL BLADEF PRINTING B4UL FUNCTION GAUL GRUNG. FUNCTION BAIL Sf —~ FUNCTION GA— A CONCTMW LEVER BAL 7 FUNCTUW LEVER BHU MULLER Leo eaeaz see. - me YA eg a> (zn ' REAR ANY FUNCTION LEVER SLRS CUE SHEET FUNCTION LEVER FIOUE SHUT PUSH BA FOWCHIW GAUL BLADE FUNCTION LEVER TENG (SEE KLUSTERTION 9) Fiz, 15 Page 15 SECTION AB8),.139 and the carriage return latch bar are both piv=- oted on the same screw the latch bar will be reset into engagement with its latch (Fig. 16). In the meantime the function lever bail will have been returned to its upper position and the carriage return function lever extension will have been moved down below the carriage return latch bar. During the time that the carriage return operating lever was being operated by its spring, the lock bar was moved through a se- ries of levers until its notch engaged with the lock bar latch (Fig. 16). This held the carriage return clutch members disengaged so as to insure a complete return ofthe carriage. One end of the dashpot lever is attached to the dashpot plunger and the other end pro- jects into the path of the typebar carriage. Just before the typebar carriage has returned to the beginning of the line, the left-hand margin adjusting screw (attached to the car- riage) strikes the end of the dashpot lever driving the plunger into the dashpot air cham- ber absorbing the shock (Illus. 2 When the typebar carriage returns to the beginning of the line, the dashpot lever strikes against the lower end of the lock bar latch, releasing the lock bar and carriage re- turn clutch fork which inturn permits the car- riage return clutches to engage. The carriage return lock bar extends be- yond its latch so that it may be operated man- ually. LIASHELT LkVER Figure Shift and Letter Shift The figure shift function lever, third from the right, when selected will move the figure shift push bar up tobring its notch in- to the path of the function bail (Fig. 15). This push bar when moved by the function bail will turn the right end of the shift link, to which it is connected, toward the rear of the printer and the left end of the link toward the front of the printer (Fig. 17 & Illus. 8). The shift lever which is engaged in the left end of the link is thus moved so as to pull the rear end of the platen assembly down- ward through the medium of the shift vertical link. The platen roll will be brought to its upper or shifted position. The letters push bar is connected to the left-hand side of the shift link. When the letters push bar is operated by the function bail the action on the platen assembly will be reversed, bringing the platen down to the let- ters position. The shift detent is provided to hold the platen asseribly firmly in either the shifted or letters position. Sixth Vane The lower end of the spring attached to the sixth vane fits into the notch in the for- ward end of the letters push bar (Fig. 22). When the platen is in the figures position, LOK BAR LATN —_ — LOCK BAR @ Ol CARRIAGE RETURN CAERSTING LEVER SPRING. CARRE RETURN COERATING LEVER is SPAIMG SHAFT f CARRIAGE RETURN CLUTOH FORK - if OO LEER ee CHRO RETUUN CLUTTER Te RV CTION BAIL pe CARRIAGE RETUs a icaclaa LEC EUTENSION (om, ~ | eer RAGE RETURN LATCH BAR ____ capeack RETURN RESET BAR L_ ggeaGE RETURN LITE BBR LTH (SEE ULLUSTRATION E) Fig. 16 Page 16 the letters push bar is in its forward posi- tion and the rear edge of the sixth vane is moved down. When the platen is in the letters position the rear edge of the sixth vane will be in its upper position. When the letter "s" or "M" is selected and the platen is in the letters position the bell and motor stop func- tion levers will be inoperative because the sixth vane prevents their selection. With the platen in the figures position the sixth vane will not prevent the selection of the bell or motor stop function (See "Motor Stop Function" and "Signal Bell Function"), Note: Printers not equipped with me- chanical motor control have period on the upper case of "M' and the motor stop function lever is omitted. Some printers are arranged to ring the sig- nal bell on the upper case "J" or on the "Blank" in which cases the bell function levers are designed to be se-~ lected on these combinations. The sixth vane however is not used in con-~ nection with the signal bell function when the bell is made to ring on the "Blank" combination, as the platen may be in either the "Figures" or "Letters" position. Spacing Function Spacing other than that accompanied by printing (such as spacing between words, etc.) PLSTEN CRETE SHEL QETENT- SMT STOP POST SMET VERTICAL LINK SECTION AB8,.139 is accomplished in the same manner as that de- scribed under "Spacing" except that there is no pullbar to be selected, Unshift on Space Function LNE FEED VERTICAL LINK SMUT LEVER If desired the printer may be arranged to shift the platen to the letters position on both the space and letters combinations. This is accomplishe