US2273195A - Typewriting machine - Google Patents

Description

Febe 17, 1942. HELMOND 2,273,195

TYPEWRITING MACHINE Filed June 29; 1939 5 Sheets-Sheet l INVENTOR W/LLM/V E f/[LMOND BY I ATTORN EY l Feb. 17, 942. W.F.HELMOND 2,273,195

TYPEWRITING MACHINE Filed June 29, 1939 ATTORNEY Feb. 17, 1942. w.- F. HELMOND 2,273,195

TYPEWRITING MACHINE Filed June 29, 1939 5 Sheets-Sheet 5 INVENTOR W/LL/A/V E f/fLMO/VD BY I Q Q ATTORNEY Patented Feb. 17, 1942 'rr'rnwnrrnzo F. Helmond, west" Hartford, come. asv signer ,toUndenUood Elliott Fisher Company; New York; N. Y, a corporation of Delaware 1 I Application June as, 1939, seasons. salsa-1 topiar -51st) i This invention relates" to typewriters or the like and more particularly to frameamimask structures therefor. It is a common practice in adding machines or'the like to mount printing instrumentalities and other mechanisms upon's sturdy main frame and to dress the exposed mechanisms or unfinished surfaces thereof by typewritersand I operating parts of the machine is-seated-upon-a base having the. form of estrous. open mask: frame and the component maskr-sectionsr arc ,abo' fastenedto lsaid base and riseupwardly there from to cover the main frame. The -.severa1 mask-parts are rigidly Joined together abovethe base by concealed means. Some of the maskparts are preferably jointed by meshing cleatsor ornament'al covers. In most cases it isvery diill- 1 cult to fasten these ornamental covers to the machineproper without leaving the fastening devices exposed and consequently reducing the attractiveness and salability of the machine. In

some cases the entire mainframe and also the 7 carriage has been covered by component'rmaskstructures; Such mask structures are usually united along their joints by exposed, unsightly fastening devices.

It is an object of the invention to provide means whereby covers'may be accurately registered or located upon adjoining frame or mask walls and rigidly interlocked therewith.

It is another object of the invention to eliminate exposed or apparent-devices for fastening masking-covers upon the machine. V

Still another object of the invention is to provide a mechanism-ensuing 1 composite maskstructure for typewritingor like machines which is cheap to manufacture; structurally strong when assembled, and pleasing in appearance.

Another object of the invention is to provide a Jointed mask-structure that is conveniently and rapidly assembled upon the machine or disassembled therefrom.

A further object is toprovide a mask-assembly which evidences no devices by which the component mask parts are held together and attached to'the machine. i

A'further object of the invention is the division of amask intosimpleicomponent mask-sew tions that are adapted to be joined'into anextremely rigid, well-fitted, sound-proof assembly.

Another object of the invention is the provision of a unitary displaceable cover for theribhon-spools and the" type-basket. a.

A still further obiect of-the' invention is the provision of a common base-frame wheretothe main frame as well as the component mask-parts .arefastened.

The main-frame of thelmachine is covered by a multiple-piece mask that includestwo opposite side-walls having inwardly extending shoulders rising upwardly and rearwardly from the keyboard to shroud opposite front-portions of the main frame and mechanismssupported by it.

A unitary displaceable cover for both the ribhon-spools and the type-basketspans the space between the said shoulders, and a cowl or cover in back of and below the carriage covers the rear of the machine. The main frame bearing the flanges which render the composite mask-structure extremely rigid, and the joints of the composite mask simulate ornamental design-lines, The carriage is masked along its sides the rear region by a multiple-piece mask. the several pieces of which are interlocked along theiriolnts in such manner as to substantially: significance as such. ,1; Any of the aforesaid maslrvsections can be quickly removed from the machine to make repairs and adjustments at certain pointsotthe machine without greatly disturbing the positions of the other mask-sectionsof the machine g In the accompflnyins drawingsz, Figure 1 is a perspective view ofv a typewriter incorporating the novel composite ask.

tion..

vided to gain access tothe ribbon 'spools ond-t the masking side wallsa Figure 2 is an enlarged perspective view oi. a catch devicethat is adapted to resilientllholdga displaceable mask-section in normal,- closedposi- Figure 3 is a perspective view arable mask-sections of the composite mask separated from each other. andv thew base -frame, which forms part of the meanslby which'the composite mask is attached to. themain frame.

Figure 4 is an internal P spective view of'a concealed hinge-joint of a cover.

Figure 5 is a plan view of the open base-frame whereupon the main frame and-the composite masklssecured.

Figure 6 is an internal perspective-view show ing united several of the composite mask-sec tions which constitute the front po'rtio f the Figure 7 is a perspective view of-thea'ssem bled typewriter. including the composite some of the parts of the keyboard having been left 01! and the unitary displaceable' -cover pro types, having beendisplaced.

7 Figure B is a transverse cross=section= alon the dotted line ll of Figure 5 showing a=ide will ofjthe base frame and showing'asjportion one of the main frame walls and a portion fen of Figure 9 is ajskeletonlzedporspectivc showing the-main mechanism-supporting frame seated upon the base frame. .r. w

Figur 10 is a rear perspectivev ewiohzthe use sembled carriage equipped with interlocking shrouding sections.

V "Figure 11 illustrates a device for clamping one mask portion upon another.

Figure 12 is a sectional view along the lines l2-I2 of Figure 3 showing a rear-cover and a side-wall drawn into meshed interlock by a spring-finger.

Referring now more particularly to the drawings, the typewriting instrumentalities may include an array of type-bars l pivotally mounted upon a segment H (see Figure 7) and selectively operable through actuating trains, not shown, .by type keys l2 mounted upon the front-ends of key-levers 13. The front-ends of the type-bars III are nested in a curved type-rest IS. The typing instrumentalities ill, l2, I3v and other mechanisms including the rest 45 are supported upon an unfinished main frame seen in Figure 9 to consist of opposite side walls l4 and a number of connecting transverse bars, oneof which may constitute a supporting bar I5 for the carriageguiding rails I1 and another of which may constitute a slotted bar II upon which type-bar actuating parts are pivoted.

A'carriage l9 seen in Figures 1, 'l and 10, is slidingly mounted upon the rails I! for movement in letter-feed and return directions and supports a platen-roll 20 against which the types will strike when the type-keys i2 are operated. Type impressions may be effected by means of a transfer ribbon 23 that is threaded through openings 22 in a centrally disposed ribhon-vibrator 24 (see Figure '7) and wound upon spaced spools 25 that are supported by horizontal brackets 25 extending inwardly from the sidewalls of the main frame. Themain frame l4, l4, supports virtually all moving parts oi. the typewriter including also the vibrator 24.

In power operated machines, a motor 28 and r a transmission housing 29 may be located below the carriage and attached to the rear-end portion of the main frame l4, l5 and ill, see Figure 9. Such motor-drive may include a belt-drive II tocontinuously rotate a power roll 3! that is operative to drive the type-bars ID in a manner not shown, under control of the type-keys l2.

Thexside-walls H of the main frame consist preferably of punched sheet-metal plates having perforations 32 at various suitable locations so that access can be gained through the plates for making adjustments to various mechanisms such as, for example, the case-shifting mechanism, not shown. 7

p The main frame [4, l6, I8 is seated, as seen in Figure 9, in a shallow, protecting and reinforcingbase-frame 34 which is preferably a lowfour-walled, rectangular, open casting or molding having two lugs 35 extending inwardly from the bottom of each of its side-walls 36. Each sidewall l4 of the main frame is provided with two threadedbosses 31, one at the front and anotherst. the rear, which match the lugs 35 of ,the-base-frame. Screws 32 passing upwardly through perforations in the base-lugs 35 and extending into said threaded bosses 31 secure the frame removably to the base. As seen in 23 ml? -.9.-the base-frame 34 surrounds, conceals,

rotects andreinforces the bottom of the main fram iz Eachbase side-wall 35 is thickened along are countersunk in the feet 40. A uniformly cross-sectioned bar 45 extends along the front of the keyboard and is bent rearwardly at each side to flank the opposite base side-walls 35, whereto it is fixed by concealed screws 45 passing from within through the side-walls 36 of the base. See Figures 5 and 9. The portions of the bar 45 flanking the, sides 35 of the base constitute convenient finger-holds for lifting and carrying the machine. The machine may also be carried by the transverse forward bar-portion 48, The bar45 protects the frail keyboard mechanism, and although of relatively small cross section is strong and virtually unbreakable it formed of a suitable material that can withstand shocks. Preferably the bar is die-cast of a light alloy such as a magnesium or aluminum alloy. It may, if desired, be bent from steeltubing or formed of a non-brittle or reinforced plastic. The bar 45 is slightly flattened where it is attached to the side-walls 36 of the base and ledges 50 extending outwardly from the base overlie the bar.

The base-frame 34 not only surrounds and protects the main frame at the bottom portion thereof as hereinbefore stated but also forms the base of an assembled ornamental mask, generally designated by the numeral 5|. The exterior of the base has an ornamental finish. The assembled mecha'nism-encasing ornamental mask 5| includes two separate opposite side- walls 52 and 53 rising upwardly from the side-walls 35 of the base 34. Each of the masking walls 52, 53 has an integral, inwardly extending, broad shoulder 54 rising upwardly from the keyboard and sweeping in a curve rearwardly'toward the platen 20 slightly above the elevation of the ribbon-spools 25. The side- walls 52 and 53 are of diminished height below and in back of the carriage I 9 to clear the carriage trackways ll. A low front member or connecting wall 55 between the said shoulders 54 rises a short distance upward in back of the keyboard. The clearing between the said side-wall shoulders 54, immediately above the connecting wall 55 (see Figure) is prefe:- ably at least coextensive with the space occupied by the array of type-bars I5 nested in the typebar rest 15, so that the types are accessible through the clearing for cleaning. At the top, in front of the platen, the shoulders 54 have cutouts 51 to allow access to the ribbon 23 and ribbon spools 25. A unitary displaceable intermediate shroucling member or cover 59, seen in Figures 1, 3 and '7, normally fits laterally between "the said side-wall shoulders 54, above the said transverse connecting wall 56 and thereby normally'conceals the type-bars Hi, the ribbon-spools 25 and the major part of the ribbon 23. The side- walls 52 and 53 have each underneath the carriage and in back thereof aninwardly extending stiffening shoulder or flange 60, between which there extends a rear-cover 5 I The flanges 50 may extend forward of the carriage trackways IT to form inwardly offset side-wall portions 52 adjacent to the ribbon-spools 25.

Novel devices are provided for quickly and conveniently assembling and fastening the composite mask portions 52, 53, 56, 59 and 5| together upon the machine. These devices are, according to the preferred form of the invention shown, not visible from the exterior of the machine. The individual mask portions 52, 53, 5B, 58 and Si constituting the composite mask-5i are of such form or shape as to be conven ently and economically manufactunzd; and when assembled have, due to the total absence of exposed fasten-- The joining lines of the several mask-pieces seemingly represent mere lines of the generalv transverse rear-cover is accurately registered 'remtfitofih opposite side-walls 52 and 58.

More specifically, ea PlatQend of the cover 5| has an integral cleat or ridgeqra hichiits a groove formation or cleat l9 providerhenlhe 60 adjacent side-wall flange 60. See Figures 3 and 5 h 0uding portion 89 that is substantially equal 12. The associated cleats l8, 15 at each end of the cover or wall 6| constitute intermeshing tongue-and-groove joints between the side-walls 52 and 58 and the cover 6| along each cover-end, whereby they are accurately registered and rigid-' ly interlocked. The side-walls '52, 53 and the rear-cover 8| of the mask are stiffened by inwardly extending bottom flanges 88 and 84 respectively (see Figures 1, 3 and 8), which are widened at several points and provided with threaded holes 85 that overlie corresponding vertical perforations 86 in lugs 81 extending inwardiy from the walls of the base-frame 36. screws tions 88 extend into the threaded holes 85 to fasten the side- walls 52 and 53 and the rearcover 8|, in intermeshed registration upon thebase. ,The holes 86 in the base are countersunk ornamental design. The low transverse front- '5 and slightly oversized, as seen in Figure 8, to wall 55, as seen in Figures 1, 3; 6 and-7, has at allow for manufacturing differences in the maskeach end at least two rearwardly extending proparts 52, 58, 58 and GI; In assembling the mask tuberances 84 registering with holes or perforaupon the machine, the side- walls 52, 53 and the tions 55 provided in flanges 68 extending latrearw-cover 6| are clamped to the base by means erally toward each other from the shoulders 54 10 of said screws 88 in exactly relativelyregistered of the side- walls 52 and 53. A latch lever 58 is positions. Said oversized holes 85 give sufllcient pivoted on the inner side of each end of the freedom to effect this, irrespective of the manufront wall 55 upon a stud or pin 12. Each lever facturing diflerences. The side-walls 52, 58 and includes an arm 69 which cooperates with the the rear-cover 8|, when anchored by the screws adjacent flange 66 to normally'clamp or hold the 88 to the base, form a flrm, interlocked, selffront-wall 56 to the adjacent flange 56 in regissustaining mask-structure, rising upwardly from tered' position, and a lever-arm I0, constituting the base 86gout of contact with the framework, a handle by which the lever 68 can be manipuand no means are visible or apparent whereby lated. The flanges 66 are slightly offset rearthe composite mask is supported on the main wardly of the shoulders 54 so that the front side frame l4, l6, l8. The side-walls 52 and 58, alof the cover 55 and the front side of the shoulders though only fastened to the main frame at the 58 are substantially flush. The clamp arms 55 bottom, through the medium of the base 86, are are cam-shaped to easily glide on to the flanges extremely well braced in their upright positions 68 when they are rotated from ineffective poby the rear-cover 8| through the invisible intersition to eifective position, which positions are looking tongues and grooves 18 and I8 and also respectively illustrated in dotted and full lines through the registering devices 54, 65 of the in Figure 6. Each lever 58 is held against rotafront-wall 55. The tongues and grooves are so tion by a strong, broad-faced spring-washer 1| arranged upon the side walls 52 and the rear underlying each lever 68 upon its pivot-pin 12. shrouding member that the latter is readily re- The flanges 66 constitute flrm seats for the frontmovable from the side walls. In the form of thewall 66 so that the front-wall and side-walls invention shown, the screws 88 fastening the 52 will be clamped together to a firm structure rear-cover 5| to the base 85 are supplemented in The protuberances 64 are preferably in the form the function of holding the side- walls 52, 53 and of pins riveted to the front-wall 55 and these rear-cover 5| together through concealed devices pins including the pins 12 are flush with the 5 seen in Figures 3 and 12, which resiliently draw front-face of the wall 58 and therefore exter the rear-cover rightly registered upon the sidenally invisible. The wall 55 has several vertical wall cleats 19. These devices comprise springslots I4 to accommodate key-levers extending fingers 80 riveted to opposite interior upper, endrearward from the keys 16 that are associated portions of the cover 6| that normally extend at with the tabulating mechanism of the machine. their free ends under lugs or pins 9| on the The wall 55 has at the top a rearwardly-tumed side-wall flanges 60. The rear-cover 8| is quickflange 8i rendering it strong and rigid. 1y assembled upon the side- walls 52 and 53 by The transverse rear cover or shrouding memsliding the cover along the side-wall cleats 18 her Si is seen in Figure 3 to have a straight verso that the resilient fingers 80 will slide under tical wall it merging into a forwardly extending the pins 9| and thereby will draw the coverl at portion consisting of a raised cowling 15 extend- 18 into full mesh with the opposite side-wall ing underneath the carriage and dropping downcleats 18. The spring fingers 90 together with wardly at each end to be substantially continthe screws 88 keep the side walls 52, 53 and the uous with the side-wall flanges or shoulders 60. rear-cover 5i tightly interlocked upon the base The cover 5| shrouds mainly the electric motor and the creation of vibratory noises in the cleat- 28 and the transmission housing 29 seen in Figjoints is avoided. It should be understood that it ure 9. A lateral slit ll seen along the rear edge may sufllce to hold the rear-cover interlocked of the cowling 15 provides an escape for the directly with the side-wal1s without fastening heat generated by the motor 28. it to the base. Any of the individual mask-por- Eflicient means are provided whereby also the 55 tions 52, 53, 56 and GI can be temporarily removed to expose certain mechanisms, such as for example the case-shift adjusting mechanism, without removing any other mask-portion or portions from the machine.

The unitary cover 59 has a forward type m'wsgwnn the nest of types 2| and blends into a rearvmiwdisposed, horizontal top-portion 94 (see Figure D'rthat spreads outwardly over the ribbon-spools 25 seen inf-"ga el. The ribbon-spools 25 and the types ID are therefore normally fully covered and the cover 55, being in interfltting engagement between the side wall shoulders 58, forms therewith a substantially continuous front and top face. The entire cover 58 pivots along an axis parallelly adjacent to the platen carriage. More specifically as seen in Figure 4 two opposite rectangularly bent brackets 82, secured by rivets 85 to the underside 88 passing upwardly through the base-perforaof the cover 59, near opposite'ends thereof, have each a downwardly pending branch 99 provided with an L-shaped slot-opening 96, whereby the opposite ends of the cover 59 are pivotally seated upon two opposite pivot posts 83 projecting inwardly from the side- walls 52 and 53 of the mask. A spring 51 connected to a bracket-ear 88 draws the brackets 82 and therefore the cover 59 resiliently downward about the pivot-posts 93. The springs 81 are preferably anchored to pins 98 on opposite side-walls I4 of the main frame. When the cover is displaced upwardly and rearwardly to the position shown in Figure 7, the springs 9! cross the center of the pivot-axis and thereby will act to hold the cover 59in open position, whereat it may lean against the platen 23. In this position the type-bars are accessible for cleaning and also the ribbon may be changed. The slots 95 are L-shaped and open toward the rear as seen in Figure 4 in order to allow the removal of the cover 59 in its open position from the pivot-pins 93. The springs 9! are, however, preparatory to the removal of the cover, unhooked at either of their ends. It should be noted that the tendency of the cover-brackets 92 to unseat from the pivot-pins 93 is normally resisted by the action of the springs 81. The cover 53 is normally in interfitting position between the mask shoulders and has integral cleats I53 along its side edges, which cleats normally mesh with groove-cleats I 04 integral with the opposite innet edges of the mask-shoulders 54. The grooves .III of the cleats I face forwardly-andthe associated cleats I 03 on the cover face toward the rear. Thus the cleats I03 and'IM are capable of separation when the cover is swung open. Aside from having the function of accurately registering the cover upon the side-wall shoulders 54. the cleats I53 and I84 reinforce and support the cover in closed position and also brace the front-portion of the assembled mask, particularly the upper front portions of the side walls 52. The cover 58 has a central cut-out I01 adjacent to the printing point directly in front of the platon to provide a clearance for the types 2! to move against the platen. Similarly, the top- ,portion 94 of the cover has a slight raise intermediate the ribbon-spools to provide on the underside of the cover av passage I88, see Figure 7. The cover spreading over the ribbon-spools 2b is low enough to leave the full typing line lilo exposed, see Figure 1. The cover 59 has at the front a finger-hold in the form of an attached button its. Clips or detents III (see Figures 2 and 8) attached along the back-side of the cover at the bottom, in conjunction with pins I I2 pro- .iecting upwardly from the flange ill on the transverse wall E8, resiliently hold the cover 52: in closed position. The clips III are arranged in integral pairs riveted to the back-side of the cover of which each pair engages the opposite sides oi one of the pins H2. The clips of each pair are flared outwardly from each omer to form tapered pin-receiving throats I I 3 and have also detenting seatsJlWFigure'Zi nowthe typewriter carriage I5, il-

lustrated best in Figures 7 and 10, the platen 2c is revolvably secured upon opposite carriage endplates H5. The end-plates II5 are mounted on opposite ends of a bar II! that is guided for letter-feeding and carriage-return movements ill tending upwardly from a stationary column I23 protruding upward through a cut-out I2I in the rear cover BI, seen in Figure 3. A paper-table I23, substantially coextensive with the platen 20, pivots on an axis I25 directly in back of the platen and extends normally upwardly and rearwardly thereof to overlie a rack I26 having margin-stops I21 adjustable thereon. The table I23 rests normally against a stationary part on the carriage, not shown, but can be swung forward about the axis I25 to gain access to the stops I21 for adjusting them. The tabulator rack H1 is situated in back of the margin-stop rack I26 and is with other mechanisms including parts I", II 8, concealed by a hood or shroud I28, extending from end to end of the carriage and having a horizontal top-shelf I30 and a downwardly pending rear-wail ISI. The shroud, hood or cover I29 is flanked by opposite side-covers I33 and I34, covering the end-plates H5 of-the carriage. The side-covers I33 and I34 may be attached to the carriage-ends H5 by any suitable means. These means may or may not be concealed. In the form of the invention illustrated in the drawings, the side-covers I33, I34 are fastened to the end-plates II5 of the carriage by means of screws I35. The side-covers are preferably spaced from the end-plates II5 by sound insulating spacers, such as bushings I31 of fairly hard rubber. The side-walls have wide flanges I38 extending toward each other and covering the end-plates H5 at the front, top and back. The shell I30 and the rear-wall I SI of the hood I28 are substantially flush with the side-wall flanges I38 at the top and rear. In order to fasten the hood I29 in correct position relative to the side-covers I33 and I34 to thereby provide a well-jointed, rigid mask-assembly, it is con-' ceived to provide means to register and lock the side covers I33, I34 and the hood I29 upon each other. The side-wall flanges I38 for this purpose have along the inner edges where they join the hood I29, tongues or cleats HI whereupon the hood is accurately seated or registered by U- shaped ears I42 provided along both ends of the hood I29. In the drawings, three such ears I42 are shown to hook over the rim I of each side cover. one on top and two at the back. Con tinuous grooved cleats may be provided instead of the several ears I42. The ears M2 in effect extending bracket-arm M5 fastened to one of the carriage-end plates H5. The clamp-arms I 44 have cam-edges Ill to engage the underside of forward projections I53 on the hood ends. In order to position the hood I29 in registered position upon the side-walls, the clamp screws I53 are loosened and the clamp-arms I44 are turned outwardly, clear of the projections I53. After the hood is properly seated in respect to the sidewalls, the clamp arms I44 are swung toward each other to wedge the hood I29 tightly upward. The top ends of the clamp-arms I44 lie in front of forwardly projecting abutments I54 on the hoodends and will press the hood rearwardly when the clamp screws I are being tightened. The clamp arms I44 may be slightly resilient and the bracket-ears. I, so, relative to the abutments that the arms lfljwill'bend as seen'm Figure 11 when, drawn' igh ifiimfii, a??

bracket-ears lliby thescrews iilr A convenient procedure to assemble the carriage maskconsists of first loosely. screwing the side-covers l33, ;i3l to the carriage end-plates. Hi, to secondly-introduce the hood I29 inter-e mediate the side covers, to thereafter tighten the clamps I and last to tighten the screws I38.

Either end-cover In or L may be removed This procedure, however, need not be followed.

without'removing the other. If it is desired to,

remove the hood I29, either-sneer bothof the end-covers I33. I34 may be loosened by thescrews I36 to. enable the withdrawal of the hood.

, 5 ama -mists his lesst'one of said shoulders on'each.side wall, fitting each other in a manner-to interlock rigidly said side walls with the intermediate member laterally and to I render said intermediate member removable from 3 said side walls, said rear intermediate member fitting the shoulders of the opposite side walls in a manner to provide a rear wall and forwardly extending portion which is substantially con-' tinuous with. the shoulders of the side walls at :bothtopandbackofthemask.

3. In a typewriter, a mechanismensuing self sustaining composite mask comprising two oppositel'y disposed side walls each having a front The hood :29 has a downwardly-turned lip m:

at the front that extends a short distance underneath the paper apron I23. portions I33; I31, I29 of the carriage are prefer- The several maskably struck up from thin aluminum sheeting and' the above-described novel interlocking joints render the'composlte structure thereof extremely shoulder extending toward the, other. an inter-,-

mediate rear shrouding memberfirmly connecting said side walls at the rear; and an intermediate front andtop shrouding member.comprls-. ing ribbon spool covers and atype shroud section, said shoulders and said front intermediate mem- "ber having" tongue and groove formations fitting each other in a manner to interlock rigidly said.

side walls at the front laterally with said front rigid and well-connected. notwithstanding the relative frailness of the independent pieces.

The several mask-sections covering the stationary part of the machine rise upwardly from the ,base '34 free oi the main framework I4, I!

and i8 and the several mask sections are fastened,

together independent of the mechanism-supporting frame and are therefore self-sustaining. The mask, as seen in Figure 8, is sound insulated from the main frame by rubber washers I:

It is to be understood that the various means shown for registering and fastening certain mask-parts together may also be used to advantage to fasten certain other machine covering parts together. The base frame 34 although used to great advantage is not to be considered an essential part of the invention. Certain mask parts may be used without using others. The side-frame pieces ll may constitute themselves finished side-walls to which masking-walls orcovers are removably or displaceably joined in accordance with this disclosure.

What is claimed is:

1. In a typewriter, a mechanism-encasing composite mask comprising oppositely disposed spaced side walls provided with rear and top shoulders, a rear intermediate shrouding member defining a rear wall and a forwardly extending portiomand tongue and groove formations on said rear intermediate member and at least one of said shoulders on each side wall, fitting each other in a manner to interlock rig-idly said side walls with the intermediate member laterally and to render said intermediate member removable from said side walls, said rear intermediate member fitting the shoulders of the opposite side walls in a manner to provide a rear wall and forwardly extending portion which is substantially continuous with the shoulders of the side walls at bothtop and back of the mask.

intermediate member and to render said intermediate member displaceable, said shoulders being formed and said front intermediate member fitting the said shouldered side walls in a manher to present therewith a substantially continuous front and top mask face.

4.. In a typewriter, a mechanism-choosing selfsustaining composite mask comprising two oppositely disposed spaced side walls each having a front shoulder extending toward-the other, and

a hingedly mounted intermediate shnouding member comprising ribbon spool covers and a typeshroud portiomsaid shoulders and said intermediate member having tongue and groove.

formations fitting each other in a manner to interlock rigidly said side walls laterally with said intermediate member and so that said intermediate member is associable with the side was for hinged movement to and from shrouding position, said shoulders being formed and said intermediate member fitting the said shouldered side walls in a manner to present therewith a.

substantially continuous front and top mask face.

5. In a typewriter, a mechanism-messing selfsustaining composite mask comprising two oppositely disposed spaced side walls each having 2. In a typewriter. a mechanism-encasing com- 9. front shoulder extending toward the other. and a hingedly mounted intermediate shrouding member comprising ribbon spool covers and a type shroud portion, said shoulders and said intermediate member having tongue and groove formations fitting each other in a manner to interlock rigidly said side walls laterally with said intermediate member so that said intermediate member is associable with the side walls for hinged movement to and from shrouding position, and detent means adapted to releasably hold 1 the intermediate member in shrouding position with the tongue and groove formations in inter locked engagement.

6. In a typewriter, a mechanism-encasing mask comprising vtwo oppositely disposed side walls each having a front shoulder extending toward the other, a low front member connecting said side walls at the lower regions of said shoulders, a displaceable intermediate front and top shrouding member comprising ribbon spool covers and a type shroud section, said shoulders and said intermediate member having tongue and groove formations fitting each other in a manner to interlock rigidly said side walls at their upper regions laterally with said intermediate member and to render said intermediate member displaceable, and cooperative means on both said members for releasably detenting said shrouding member in interlocked relation with the said side walls.

'7. In a typewriter, a mechanism-encasing mask comprising two oppositely disposed side walls each having a front shoulder extending toward the other, a low front member connecting said side walls at the lower regions of said shoulders, a displaceable intermediate front and top shroudin-g-member comprising ribbon spool covers and a type shroud section, said shoulders and said intermediate member having tongue and groove formations fitting each other in a manner to interlock rigidly said side walls at their upper regions laterally with said intermediate member and to render said intermediate member displaceable, said shoulders being formed and said intermediate member being adapted to fit the said shouldered side walls in a manner to present therewith a substantially continuous front and top mask face, and cooperative means on both said members for releasably detenting said shrouding member in interlocked relation with the said side walls.

8. In a typewriter, a mechanism-encasing composite mask comprising a base frame having side and rear masking walls, separate oppositely disposed side walls anchored to the said base frame and provided with rear and top shoulders, a rear intermediate shrouding member defining a rear wall and a forwardly extending portion, and tongue and groove formations on said rear intermediate member and said shoulders fitting each other in a manner to interlock rigidly said side walls and intermediate member laterally and to render said intermediate member removable from said side walls, said rear intermediate member fitting the shoulders of the opposite side walls in a manner to provide a rear wall and forwardly extending portion which is substantially continuous with the shoulders of the side walls at both top and back of the mask.

9. In a typewriter, a mechanism-encasing selfsustaining composite mask comprising an open base frame having side and rear masking Walls and machine-supporting means within said walls, oppositely disposed side walls anchored to the said base frame and provided with rear and top shoulders, a rear intermed te shrouding member defining a rear wall anu a forwardly extending portion, and tongue and groove formations on said rear intermediate member and at least one of said shoulders on each side wall, fitting each other in a manner to interlock rigidly said side walls and intermediate member laterally and to render said intermediate member removable from said side walls, said rear intermediate member fitting the shoulders of the opposite side walls in a manner to provide a rear wall and for- .wardly extending portion which is substantially continuous with the shoulders of the side walls at both top and back of the mask.

10. In a typewriter, a mechanism-encasing self-sustaining composite mask comprising oppositely disposed spaced side walls provided with front shoulders and rear shoulders, a hingedly mounted intermediate front shrouding member,

comprising ribbon spool covers and a type shroud portion, said shrouding member being normally positioned to present with said shouldered side walls a substantially *continuous front and top face at the front of the machine, a rear intermediate shrouding member defining a rear wall and a forwardly extending portion, and tongue and groove formations on said rear intermediate member and said rear shoulders, fitting each other in a manner to interlock rigidly said side walls and rear intermediate member laterally and to render said rear intermediate member removable from said side walls.

11. In a typewriter, a mechanism-encasing self-sustaining composite mask comprising oppositely disposed spaced side walls provided with front shoulders and rear shoulders merging into top shoulders, a hingedly mounted intermediate front shrouding member, comprising ribbon spool covers and a type shroud portion, said front shrouding member being normally positioned to present with said shouldered side walls, a substantially continuous front and top face at the front of the machine, a rear intermediate shrouding member defining a rear wall and a forwardly extending portion, and tongue and groove formations on said rear intermediate member and said rear shoulders, fitting each other in a manner to interlock rigidly said side walls and rear intermediate member laterally and to render said rear intermediate member removable from said side walls, said rear and top shoulders being formed and said rear intermediate member fitting the rear and top shoulders of the opposite side walls in a manner to provide a rear wall and forwardly extending portion which is substantially continuous with the rear and top shoulders of the side walls at both top and back of the mask.

12. In a typewriter, a mechanism-encasing composite mask comprising, oppositely disposed spaced walls provided with shoulders extending toward each other, an intermediate shrouding member, and tongue and groove formations on said intermediate member and said shoulders, fitting each other in a manner to interlock rigidly said spaced walls with the intermediate member laterally and to render said. intermediate member displaceable from said spaced walls.

13.1n a typewriter, a mechanism-encasing composite mask comprising, oppositely disposed spaced walls provided with shoulders extending toward each other, an intermediate shrouding member, and tongue and groove formations on said intermediate member and said shoulders, fitting each other in a manner to interlock rigidly said spaced walls with the intermediate member laterally and to render said intermediate member displaceable from said spaced walls, said shoulders being formed to accommodate said intermediate member in a manner to present therewith a substantially continuous external face.

14. In a typewriter, a mechanism-encasing composite mask comprising, oppositely disposed spaced side walls provided with rear shoulders merging into top shoulders, an intermediate shrouding member defining a rear wall and a forwardly extending portion, and tongue and groove formations on said intermediate member and said shoulders fitting each other in a manner to interlock rigidly said side walls with said intermediate member laterally and to render said intermediate member removable from said side walls.

WILLIAM F. HELMOND.

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