US2193970A - Printing telegraph apparatus - Google Patents

Description

March 19, 1940. KRUM ET AL 2,193,970

PRINTING TELEGRAPH APPARATUS Original. Filed May 4, 1936 "2 Sheets- Sheet 1 a? FIG. I I84 :83

49 94 a4 59 I as 52 6| I06. o 6 89 57 5| 6 ,1 Y

64 5 4 9 6 g; H3 l 32 79 I37|32 n2 I33 117 I o2 I25 l2 29 e 27 I28 32 27 I8 ya [I I 29 33 Zinnentor O HOWARD L. KRUM CARL w. SWAN V (Ittorneg March 19, 1940. M r L 2,193,970

PRINTING TELEGRAPH APPARATUS I Original Filed May ,4, 1956 sheets-sneet 2 FIG. 6

Snventor HOWARD L. KRUM CARL W. SWAN I8 I84- Y J I ttorneg Patented Mar. 19, ,1940

UNITED STATES PATENT OFFICE PRINTING TELEGRAPH APPARATUS lioward L. Krum, Miami Beach, Fla., and Carl W. Swan, Chicago, Ill., assignors to Teletype Corporation, Delaware Chicago, Ill., a corporation of 2 Claims.

The present invention relates to printing telegraph apparatus and particularly to apparatus for recording messages.

This application is a division of application Serial No. 77,794, filed May 4, 1936, and relates more specifically to means for driving the type wheel, in which the type wheel is sleeved upon its shaft and rotation is imparted to the type wheel at a point upon its periphery by means of an arm which is secured to the shaft.

The primary object of the invention is to prov.de in a type wheel page printer simple and eflicient means for effecting the printing operation.

Briefly, the printing telegraph apparatus for which the type wheel in accordance with the invention has been particularly developed, com prises a typing unit removably mounted on a keyboard mechanism which carries a permutation code transmitting mechanism. The typing unit comprises a single magnet selector which is articulated to a permutation code disc selector, the discs of which are adapted to be set permutatively in accordance with signals received by the single magnet selector. When permutatively positioned the code discs select one of a plurality of stop pins and permit it to be positioned in the path of an arm carried by a rotatable shaft, which is motor driven through a friction clutch and on which a type wheel is mounted. The type wheel thus may be stopped in various angular positions in accordance with the selection of stop pins. A rotatable page width paper platen is mounted in alignment with thetype wheel in a reciprocable carriage mounted on a foundation portion of the typing unit and arranged to be moved step by step by power mechanism to effect spacing and to be returned to line beginning position by the energy stored in a spring.

The single magnet selector mechanism includes a cam barrel assembly which is frictionally connected to a power driven shaft to be rotated thereby and which controls the operation of the selector mechanism. The last mentioned power driven shaft also includes a set of operating cams mounted on a sleeve or bushing in fixed angular relation with respect to each other and adapted to be driven by the shaft through a positive clutch mechanism in which driving connection is established under the control of the selector cam barrel and which is disengaged automatically at the conclusion of a single revolution of the Operating cams. One of the 'cams is effective to operate a striker member which delivers a blow to a lever to which is connected a print hammer disposed interiorly of the type wheel at the inner end of operating shanks of character carrying elements mounted in the type wheel. The blow which is delivered by the striker member is communicated through the print hammer to the shank of a character element which is thus caused to be reciprocated toward the printing platen. Another cam included in the operating cam assembly operates carriage spacing mechanism and also performs certain necessary stunts or functions. ball through the medium of which a selection established in the single magnet selector as a result of the reception of a code combination is transferred to the discs of the code disc selector through the articulation between the two selector clamped by screws to the annular member and closes the tops of the slots therein. A floating ring prevents accidental escapement of any of the type pallets from the slotted member.

For a detailed description of the structure and operation of the various elements, units, and

' combinations included in the typing unit, reference should be had to copending application of Albert H. Reiber, Serial No. 77,796, filed May 4, 1936, in which the entire printing telegraph mechanism is disclosed in greater detail.

For a complete understanding of the present invention, reference may be had to the following description, in which only as much of the details of the typing unit as is necessary to afford a complete understanding of the invention has been included, taken in connection with the accompanying drawings in which:

Fig. 1 is a perspective view of the printing telegraph apparatus described in detail in the aforementioned copending application and including the type wheel which constitutes the present invention;

Fig. 2 is an exploded perspective view of the type wheel assembly;

Fig. 3 is a plan view, partly in section, of the type wheel assembly and related apparatus;

A third cam operates a transfer,

Fig. 4 is a vertical sectional view through the type wheel and related apparatus; and

Figs. 5, 6 and 7 are perspective views of type pallets. 1

Referring now to the drawings, in which corresponding reference numerals indicate identical parts in several views, and particularly to Fig. 1, the reference numeral Ii designates generally a keyboard transmitter mechanism. For a detailed description of a keyboard transmitter mechanism which may be employed as a part of the printing telegraph apparatus to be described herein, reference may be had to United States Patent No. 1,595,472, granted .iiugust 10, 1926, to Howard L. Krum. In general, the keyboard transmitter mechanism H comprises a base casting i2 which pivotally supports at I! a plurality of key levers [4. The key levers I4 control the positioning of code bars (not shown) which correspond in number to the selecting impulses in the particular transmitting code which may be employed and to each of which is articulated a lever i9 extending upwardly from within the base casting l2.

A transmitting cam shaft i1 is rotatably mounted in bearing supports I9 carried by the base casting I 2 and has fixed thereto a gear i9 which is driven by a gear train comprising the gears 2| and 22 from a gear 23, the drive for which will be described later. The gear i9 has connected thereto the driving portion of a tooth clutch 24, the driven portion of which is connected to a cam sleeve 29. The driven portion of clutch 24 is urged by spring thrust into engagement with the driving portion and is normally restrained from engagement therewith by a clutch throw-out lever 21 which is withdrawn from restraining engagement with the driven portion of the clutch, by linkage not completely shown, when any one of the key levers I4 is actuated. 4

The cam sleeve 29 carries a plurality of transmitting cams 29 each of which includes a notch 29. A transmitting bell crank lever ii is pivotally mounted in alignment with each of the cams 29 and each lever II has an arm (not shown) which carries a cam follower (also not shown) for following the particular cam 28 with which the lever is aligned. The cam follower of each of the transmitting bell crank levers 3| tends to drop into the notch 29 in its associated cam when the notch is presented to the follower but the pivoted levers ii are effective when they occupy certain positions to block the cam follower arms of the bell crank levers 9| to prevent the cam followers from dropping into the notches 29. It will thus be apparent that as the cams 29 rotate, certain of the bell crank levers 9| will be permitted to rock and others will be restrained by the levers l9 and the rocking or non-rocking condition of the levers 9! will depend upon the permutative setting of the levers IS. The notches 29 in the several cams 28 are displaced from each other so as to be aligned helically, with the result that the bell crank levers 3| are released successively as the cams execute one revolution.

Transmitting contacts 92 are associated with each of the transmitting bell crank levers 3!, so that electrical contact is established when a bell crank lever is rocked and an open circuit condition is maintained when a bell crank lever II is restrained from being rocked. The electrical contacts 22 may be connected to a telegraph line and to the selector magnet of the typing unit to be described hereinafter, so that marking and spacing impulses may be set up by the several contacts 22 in accordance with the positioning of the levers [9. A knife edge 93 is carried by a pivoted ball 94 which has an arm 99 provided at its outer end with a follower roller 21 which follows a cam 29 carried by the cam sleeve 29. The knife edge 22 drops into blocking engagement with lugs 39 carried by the levers II when the cam barrel 29 rotates, to prevent accidental shifting of the levers I. while a code combination is being transmitted.

The typing unit or receiving portion is designated generally by the reference numeral 4i and is removably mounted on the base casting l2 by suitable bolts, not shown. The foundation of the tpying unit 4i consists of two castings upon which all of the receiving mechanism is mounted. One of the castings is designated 42 and extends from front to rear of the base casting l2 substantially parallel with the transmitting cam shaft ll. The other casting designated 42, is

also mounted on the base casting i2 and extends across the base casting l2 near the rear end thereof, substantially at right angles to the casting 42..

The casting 42 has secured thereto, bearing blocks 49 in which is rotatably mounted a vertical shaft which carries previously mentioned gear 22 and other mechanisms to be identified later. The gear 23 is fixed to the vertical shaft and is arranged to be continuously driven from the rotor shaft of an operating motor not shown.

It will be noted that no reference character has been applied to the shaft upon which the gear 23 is mounted, the reason for this being that in Fig. 1 the shaft is concealed by the various elements mounted upon it. In addition to the gear 23 by which it is driven, the unseen shaft has fixed thereto the driving portion 41 of a tooth clutch 49 and the spaced discs 49.

The discs 49 are adapted to drive a selector cam barrel Ii which is provided at its opposite ends with discs 52. Friction discs 59 are disposed between the discs 49 and 52, and the dam barrel 5i, discs 52, and friction discs 53 are confined between discs 49 under pressure so that the cam barrel 5i when not under restraint is rotated by the discs 49 fixed to the unseen shaft.

The cam barrel 9| constitutes an element of a single magnet selector indicated generally by the reference numeral 59. The selector mechanism 56 may be constructed in accordance with the teachings of United States Patent No. 1,937,- 376 granted November 28, 1933, to Walter J. Zenner. The selector mechanism 59 comprises a plate 51 mounted on the casting 42 and having an aperture 58 through which the selector cam barrel 5i extends. The plate 51 has mounted thereon a selector magnet 59 to which incoming signal impulses are applied and which, with the cooperation of the cam barrel 5| having helically arranged cam projections 6|, effects the setting of a selector lever 92 in the manner described in the above-identified Walter J. Zenner patent. The selector lever 92 controls the operation of a sword-and-T lever selector assembly 69, also completely described in said Walter J. Zenner patent, to effect the permutative setting of lever arms 94 in accordance with impulses applied to the selector magnet 59.

The lever arms 64 are provided at their outer ends with prongs 96 between which are confined disc-like portions 91 of transfer bell crank levers 68. The bell crank levers 59 are pivotally mounted maintains them in their proper positions.

at 88 and are provided at the outer ends of their arms II with disc-like portions I2 disposed in notches formed in permutation code discs of a permutation code disc selector indicated generally by the reference numeral I8.

The code disc selector may be of the type disclosed in United States Patent No. 1,821,110 granted September 1, 1931, to Sterling Morton et al., to which reference may be had for a detailed description of such selectors. The selector comprises upper and lower spaced discs I8 and I1 respectively, which have a plurality of open slots I8 radially arranged. The slots in the disc 11 are concealed, in Fig. 1, by selectable stop pins I8 extending from the lower disc 11 to the upper disc 18. The stop pins arejormed with loops 8| at their lower ends disposed in the slots in the disc 11, and a garter spring 82 surrounds the pins 18 just above their loop portions 8I and The pins I8 are of suflicient length to extend above the upper" disc 18. a

Below the upper disc I8 are rotatably mounted a plurality of code discs I5 (Fig. 4) individually aligned with the transfer levers 88 and provided, as previously stated, with notches which receive the disc-like portions 12 of transfer bell crank lever arms II. The code discs are provided with permutation code notches in the peripheries thereof, so that for eachpermutative setting of the code discs one complete alignment of notches shall be effected. Whenan alignment of code notches is thus effected, such alignment is presented opposite one of the selectable stop pins 18, which pivots about its point of engagement with the disc 11, thus moving its upper end inwardly within one of the notches 18 and into the path of a stop arm 88 fixed to a shaft 84 rotatably mounted co'axially of the code disc selector mechanism I8. The shaft 84 is kept under constant torque from the previously mentioned driving motor (not shown) through a friction clutch and suitable gearing (also not shown). When one of the stop pins 18 enters the path of the stop arm 88, the latter rotates into engagement with the selected pin 19 and is thereby stopped to present a selected portion of a type wheel 88, the structural details of which will be described later, carried by shaft 84 near the top thereof and driven therefrom, to a rotatable printing platen 81 carried by a carriage 88. The carriage 88 is reciprocably mounted at the top of frame casting 48 and is urged to its right-hand position by a carriage return spring contained within a drum 89 which is engaged by one end of a belt 9|, the

other end- 0f which is connected to carriage 88. Suitable mechanisms for spacing the carriage and for'performing line feed and carriage return operations are provided and although not shown herein, are completely shown and described in the above-mentioned copending application.

Above the code disc selector I8 and adjacent to the type wheel 88 is disposed a feed mechanism for an inked printing ribbon, such as the inked ribbons employed in typewriters. The feed mechanism includes a plate 92, removably supported above the code disc selector mechanism, which rotatably supports pins 93. The pins have secured thereto, below the plate 92, feed ratchets 84, and above the plate 92 means (not shown) for engaging and driving the ribbon spools 88 mounted on the pins 98. The plate 92 has pivotally mounted thereon a lever 81 which has at its left-hand end a pivot pin 98 on which is pivotally mounted a ratchet feed pawl 89 which is adapted to engage either of the ratchets 84, de pending upon the direction in which the ribbon is to be fed, and rotate the ratchet, as the lever 91 is rocked clockwise, to wind the ribbon on one spool, drawing it from the other spool. The right-hand end of operating lever 81 enters a slot I8I in a link I82 which is pivotally mounted at I88 on a power actuated lever I88 pivotally mounted at I81 to a bracket I88 secured to the frame casting 42.

Referring again to the tooth clutch 48, which is carried by the selected cam barrel shaft, the

driven portion III is spring urged by spring II2 toward the driving portion 41 and is restrained from engagement therewith by a clutch throwout lever III pivotally mounted on a shaft II4. Connected to the clutch throwout lever H8 is a lever arm II8 disposed adjacent to the cam barrel 8| to be actuated by a cam projection thereon to effect withdrawal of the throwout lever from restraining engagement with the driven portion III of the clutch 48.

The driven portion III of the tooth clutch 48 is connected to drive a sleeve III which has fixed thereto cams H8 and H8. Cam H8 is engaged bya cam follower roller I2I carried by a lever I22 pivotally mounted on shaft I28. Lever I24 also pivotally mounted on shaft I28 is connected at I25 to cam follower lever I22, and engages the ribbon feed mechanism operating lever I88 to impart counterclockwise rotation thereto when levers I22 and I24 are rotated counterclockwise by the action of cam II8 on cam follower I2I Lever I24 carries pivot pin I28 to which are articulated function performing bars I21 and carriage spacing pawl I28.

Above the cam H8 is box cam II8 which is provided with cam groove I29. Pivotally mounted on shaft I28 is a lever I8I which has a cam follower (not shown) disposed in the groove I29 in cam III) to be actuated by an offset (not' shown) therein. Lever I8I is arranged to be rotated counterclockwise by cam H9, and has articulated thereto a reciprocable bar I82 which is provided with an abutment I88. A striker member I84 pivotally mounted at I88 has an arm I81 disposed in the path of abutment I88.

In Fig. 2 is shown an exploded view of the type wheel assembly 86. The foundation of the assembly is an annulus I having a groove I42 of constant depth and rectangular cross section in the periphery thereof, whereby upper and lower integral flanges I48 and I44 are provided. It will be apparent that the foundation might be constructed by securing, by any desired means, flat rings to the top'and bottom of an annulus having a circumference equal to that at the base of groove I42, whereby the flat rings would constitute flanges defining a groove. However, in 'the embodiment shown in Figs. 2 and 4, the flanges are produced by forming the peripheral groove .in an annulus having an outside diameter equal to that of the flanges I48 and I 44. Radial slots I46 are cut through the upper flange I43, through the annular wall at the base of the groove I42,.and partially through the lower flange I44. The slots I48 equal in number the possible permutation 1 code combinations in the code upon which the, transmitting and receiving mechanism shownin Fig. l is intended to operate, and they are uni- In the small angular I43 is provided with a cylindrical aperture I48 extending therethrough. The flange I44 is provided in the upper face thereof with a cylindrical recess I49 coaxial with the aperture I48. The slotted flange I43 is provided with tapped holes I5I.

The slots I46 are intended to receive and slidably support and guide type pallets I62, I63 and 203 shown in Figs. 2 to 7. As shown in Fig. 7, the type pallet I52 comprises a type carrying face I53 from the rear of which extends a thin flat shank I54. The shank I54 enters one of the slots I46 and is guided in the vertical portion at the base of the groove 42 as well as in the horizontal portion in the flange I44. Each of the type pallets I52 which is adapted to seat at the bottom of a slot I46 is provided at the top of the shank thereof with a notch I58, and a coiled wire tension spring I51 seats in the recesses I56 and extends aroundall the shanks I54 of the type pallets I52 and has hooks I58 at the ends thereof engaging a cylindrical retaining pin I59, which is inserted in the grooved annulus I4I through the cylindrical aperture I48 in flange I43 thereof, and which seats in the cylindrical recess I49 in flange I44 as shown in Fig, 4. The relationship between the depth of the groove I42 and the distance of the inner end of type pallet shank notch I56 from the inner surface of the type carrying face I53 is such that the notch I56 is entirely within the groove I42 even when the inner surface of the face I53 abuts the flange I44. It will be apparent from this that the spring I51 is seated in the notches I56 within the groove I42 and urges the type pallets-inwardly radially of the grooved annulus I4I so that the inner surfaces of type carrying faces I53 are urged into abutment with the flange I44. It may be observed, by reference to Fig. 3, that the type pallet shanks I54 are of sufficient length to extend interiorly of the annulus I4I.

Directly above the spring I51 there is disposed a split ring I6I which rests on the spring I51 and is of sufficient thickness to extend above the upper edge of the shank I54 a distance equal to the extent to which the ring enters the notch I56 therein. The periphery of the ring I6I is disposed adjacent to the shoulder I62 in the shank of each of the type pallets I 52. The ring I6I extends outside of the pin I59 and rests loosely or floatingy upon the spring I51 and within the notches I56 in the type pallet shanks I54.

Above each of the type pallets I52 there is disposed in the slots I46 a type pallet I63 similar to the type pallets I52 except that the type faces I64 carry different characters than do the type faces I53, and the notches I66 in the shanks I61 open downwardly instead of upwardly. A spring I68 similar to the spring I51 and similarly engaging the pin I59 is seated in the notches I66 in the type pallet shanks I61 and urges the inner surfaces of the type carrying faces I64 into engagement with the flange I43. The spring I68 presses downwardly upon the split ring I6I and retains it centered within the groove I42 of annulus MI. The shanks of type pallets I63 rest upon the shanks of pallets I52 and since, as previously stated, the ring I6I is of suificient thickness to extend above the upper edge of the type pallet shank I54, it manifestly extends into the notch I66 in shank I61 of type pallet I63.

A cover I1I for the grooved annulus I has an aperture in the center thereof which receives the upper end of a hub member I12 which is fixed to the cover I1I in any convenient manner such as by upsetting as shown at I13 in Fig. 4. The cover III is provided on the lower surface thereof with radially extending ribs I14, equaling in width the slots I46 in annulus I4I and spaced in accordance with the spacing of such slots. At one point in its periphery the cover IN is provided with a recess or keyway I16 corresponding to the recesses or keyways I41 in the flanges I43 and I44. The cover IN is adapted to seat on the upper face of flange I43 with the ribs I14 entering the slots I46 and with the recess or keyway I16 in alignment with the keyways I41. Clamping screws I11 enter apertures I18 in the cover HI and engage the threaded apertures I5I in flange I43 of annulus I to clamp the cover I1I securely to the flange I43.

In this way a type wheel assembly is provided in which, as shown in Figs. 3 and 4, individual type pallets arranged in rows about the periphery of the type wheel are retained in slots by springs I51 and I68, by split ring I6I and by cover I1I. Sufficient clearance is provided between the ribs I 14 and the type pallets I63 to provide freedom of the pallets I52 and I83 for sliding movement radially of the type wheel and within the slots of the annulus I4I thereof, within the limits afforded by the annular retaining ring I6I. The springs I51 and I68 urge the type pallets to their innermost positions and the floating ring I6I prevents accidental displacement of the type pallets from the type wheel structure in the event that one of the tension springs should become broken and no longer maintain the type pallets under tension.

As shown in Fig. 4, the type wheel shaft 84 is provided at its upper end with a reduced portion I8I whereby there is provided a shoulder I62, The hub I12 is adapted to be mounted upon the reduced portion I8I of the type wheel shaft I84 with sufllcient freedom to be slidable with respect thereto and to seat, in its lowermost position, against the shoulder I62. An arm I83 is keyed to the type wheel shaft 84 at the upper end thereof and the arm I83 supports an arm I84 which is provided with slots I86 through which pass clamping screws I61 which threadedly engage the arm I83 and thus adjustably clamp arm I84 to arm I83. Arm I84 is provided at its outer end with depending arm I88 which enters the recesses or keyways I16 and I41 in the cover Ill and annulus I4I respectively. The arms I83, I84, and I88 serve as driving connection between the type wheel shaft 84 and the type wheel 86.

A print hammer I9I is pivotally mounted at I92 above the code disc selector 13 between the type wheel shaft 84 andthe platen 81 and facing the latter. The print hammer I9I has integral therewith a bail member I93 which extends rightwardly from the print hammer IrSI, as viewed in Fig. 3, and has integral therewith at the right-hand end thereof an operating lever I94 (Figs. 1 and 3) pivotally mounted at I96 coaxially with respect to the pivotal mounting I92. The lever I94 carries a resilient impact receiving member I91 (F'ms, 1 and 3) which is disposed in the path of the outer end of striker member I34. The impact receiving member I91 is adapted to be struck a sharp blow by the striker member I34, when the latter is operated, to rotate the lever I94 clockwise, as shown in Fig. 1, and thus rotate the print hammer I9I clockwise, as viewed in Fig. 4, to reciprocate the type pallet then in alignment with the print hammer I9I to effect printing by cooperation between the platen 81 and the type face of one o the type pallets I52 or I93.

It will be observed that in Fig. 4, a' type pallet I63 of the upper row of type pallets is aligned with the print hammer -I9I and the printing position of the platen, due to the fact that the hub I12 which supports the type wheel 88 is in its lowermost position. At its lower end, the hub I82 is engaged by a horizontal arm I98 of a shifter frame I99 located at the right side of the typing unit (Fig. 1) and arranged to be lifted and lowered by the operation of shift bell cranks 20I and 202 through connections fully described in the hereinbefore mentioned copending application. When the shifter frame I99 is lifted by the operation of the bell crank lever 29I, the type pallets I52 in the lower row are brought into alignment with the head of print hammer I9I and in alignment with the printing position of platen 81. Manifestly any type pallet in either row may be brought into operative alignment with the print hammer by shifting the type wheel to the proper level and stopping the type wheel in a particular position as determined by the cooperation of the stop arm 83 with a particular selectable stop pin 19. When the type wheel is shifted upwardly or downwardly on the shaft 84, the keyway recesses I41 and I16 slide on type wheel driving arm I88.

It will be noted that there is shown in Fig. 6 a

type pallet differing from those shown in Figs.

and 7 in that the face thereof carries no character by which printing can be effected and the shank thereof is shorter than the shanks I54 and I61. The blank or dummy pallets 283 shown in Figs. 3 and 6 are employed in those stop positions of the type wheel at which the printing of a character is not desired; for example, functions such as shift, unshift, "carriage return, line feed, etc., are functions which must be performed under certain operating conditions and it is usually not desirable to print characters when such functions are performed. It is fully set forth in the copending application that the code disc selector 13 selects a stop pin 19 for functions as well as for characters and that the type wheel is brought to a stop at certain positions corresponding to the function selections. In order that printing may be avoided when the function is performed, the short shanked pallets 203 are provided, which the print hammer i9! will not reciprocate a sufficient distance to bring the pallet into cooperation with the platen 81 and which carries no character to be recorded. With this arrangement it is not necessary to disable the striker member I36, the lever I94, or the print hammer I99 when a function is performed.

Referring particularly to Fig. 1 for a description of the operation of the typing unit 4|, attention is directed first to the'selector mechanism 56, the selector magnet 59 of which receives signaling impulses from a suitable telegraph circuit and with the cooperation of cam barrel SI, which is released for rotation at the beginning of each group of code impulses, sets the swordand-T selector mechanism 63 by means of the selector lever 82. The setting of T-levers B4 in accordance with received code impulses is transmitted to the code discs 15, through the transfer levers 68, and a particular stop pin 19 corresponding to the code signal received by the selector magnet 59 enters the path of type wheel stop arm 83. Type wheel shaft 84 is permitted to rotate until it is stopped by engagement of the stop arm 83 with the selected stop pin 19. In this manner a particular type pallet I52 or I63,-depending upon the previously established shift or unshift condition ot the type wheel, is brought into operative alignment with the print hammer I9I.

At a predetermined point in the cycle of operation of the selector cam barrel 5|, the clutch throwout lever H3 is tripped by lever H8 and cam sleeve H1 is set in rotation. The sleeve I I1 imparts rotation to the cams H9 and H8. As cam II9 rotates, its follower (not shown) is operated to cause counterclockwise rocking of lever I3I to which is articulated bar I32. Abutment I33 carried by bar I32 rotates striker member I34 counterclockwise through its engagement with lever arm I31 thereof, and thus a sharp blow is imparted to impact receiving member I91. The blow is transmitted through lever I94, bail I93, and print hammer I9I to the particular type pallet which is aligned with the hammer to cause it to be propelled toward the printing platen 81 to effect printing on paper which may be carried by the platen. The character printing movement of the type pallets I52 or I63 is effected in opposition to their retaining "springs I51 or I68 which are operative. after printing of the character has been effected to restore the type pallets to their unoperated positions in abutment with the flanges I43 and M4.

In the event that the selected stop pin 19 corresponds to a function to be performed instead of to a character to be printed, one of the dummy type pallets 203 may be aligned with the print hammer I9I in the stop position of the type wheel 86, and since the dummy pallet 283 carries no printing element, and since its; shank is shorter than those of the character carrying type pallets, it will not be actuated to produce any marking upon the paper carried by the printing platen.

It should be noted particularly that by means of the type wheel structure described herein, including the individual type elements, great flexibility of arrangement is afforded. The character printing elements may be arranged in any desired order in either the upper or the lower position to permit the association of any desired characters with particular code selections. Thus, printing units as shown in Fig. 1 may be manufactured in accordance with a single standard and may be suited to individual requirements by providing type wheels having the type pallets arranged in accordance with such individual requirements. Also a typing unit which has been individualized by being provided with a type' wheel having a particular arrangement of type pallets may be readily converted to conform to a different standard merely by rearranging the type pallets within the type wheel structure or by substituting other type pallets. I

It will be understood that the invention is not limited to the provision of dummy type pallets as shown. in Fig. 6 in those positions which correspond to function selections. tain circumstances, be desirable to effect the printing of a character simultaneously with a performance of a function in order that there may be permanent record of the performance of that function and in such cases type pallets in accordance with Figs. 5 or 7 and provided with any desired symbol may be employed.

The springs I51 and I88 engage all of the type pallets in the particular set with which each is It may, under cerassociated, and thus yieldingly retain all of the type pallets in the set under uniform tension. The floating ring Iii is provided as a safety feature to prevent escape of the type pallets from the annulus Ill and scattering of the pallets due to centrifugal force should breakage of either of the springs I61 or I" occur.

Although a particular embodiment of the in-- vention has been described herein, it will be understood thatthe apparatus is capable of many modifications and substitutions in the various elements and combinations thereof within the scope of the appended claims.

What is claimed is:

1. In a printing telegraph apparatus, a vertical shaft subjected to a constant torque, the upper portion of said shaft being reduced in diameter to produce a supporting shoulder, a type wheel comprising a hub portion slidable on said upper portion and adapted under certain operating conditions to rest on said shoulder, a disc portion secured to the upper end of said hub, an annulus depending from said disc, said annulus having a groove of constant depth and rectangular crosssection in the periphery thereof whereby upper and lower integral flanges are provided, type pallets slidable in radial slots in said annulus and arranged in two rows, printing means cooperating with the inner ends of said type pallets, aligned keyways in the peripheries of said disc and said upper and lower flanges of said annulus, and an arm secured to the upper end of said shaft, said arm having at its outer extremity a depending portion adapted to be slidably articulated to said type wheel through the instrumentality of said keyways, so that said depending portion is prevented from interfering with the operation of said type pallets by said printing means.

2. In a printing telegraph apparatus, a vertical shaft subjected to a constant torque, the upper portion of said shaft being reduced in diameter to produce a supporting shoulder, a type wheel comprising a hub portion slidable on said upper portion and adapted under certain operating conditions to rest on said shoulder, a disc portion secured to the upper end of said hub, an annulus depending from said disc, said annulus having a groove of constant depth and rectangular crosssection in the periphery thereof whereby upper and lower integral flanges are provided, type pallets slidable in radial slots in said annulus and arranged in two rows, printing means cooperating with the inner ends of said type pallets, aligned keyways in the peripheries of said disc and said upper and lower flanges of said annulus, an arm secured to the upper end of said shaft, said arm having at its outer extremity a depending portion adapted to be slidably articulated to said type wheel through the instrumentality of said keyways, so that said depending portion is prevented from interfering with the operation of said type pallets by said printing means, spaced flanges integral with said hub portion at the lower end thereof, and means embracing said hub portion between the spaced flanges thereof cooperable through the articulation between said type wheel and said depending portion for facilitating case shifting movements of said type wheel, whereby interference between said depending portion, printing means and type pallets is prevented.

HOWARD L. KRU'M. CARL W. SWAN.

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