US2312737A - Typewriting machine - Google Patents

Description

R. G. THOMPSON 2,312,737

TYPEWRITING MACHINE Filed sept. s, 1941' s sheets-sheer 1 March 2,. 1943.

March 2, 1943.

R. G. THOMPSON TYPEWRITING MACHINE Filed Sept. 3, 1941 3 Sheets-Sheet 2 `March 2, 1943.

R. G. THOMPSON TYPEWRITING 'MACHINE' Filed sept. ,3, 1941 3 Slllec-ztsf-SheetI 3 3 wu WMM y RUSSELL G Flon/szw Patented Mar. 2, 1943 Unire reina TYYEWRZTNG MACIHNE RussellG. Thompson, Elmira, N. Y., assigner to Remington Rand Inc., Buffalo, N. Y., a corpora.-

tion of Delaware This invention relates to typewriting machines, and more particularly to the type action of such machines of the type employing endwise moving type bars.

An object of the invention is to provide an improved arrangement for shifting the guiding means for each type bar to select between the printing of either of two characters as well as between either the upper or lower case printing of each character.

Another object of the invention is to provide such an arrangement for shifting the guiding means wherein the guiding means is selectively moved to denite positions at the time -of printing and is retained in each of such deinite positions against displacement by the reactive forces incident to the printing operation.

A further object is to provide an arrangement for shifting the guiding means of the type set forth wherein the initial forward movement of the type bar is much more rapid than the initial movement of the guiding means so that the initial force required for operation is reduced,

and the type bar is moved forwardly to la position wherein it may be shifted without inter.- n

ference with adjacent type bars before such shifting is etiected by movement of the guiding Other objects, purposes and characteristic feay tures of the present invention will'appear as the I description thereof progresses, during which references will be made to the accompanying drawings, wherein:

Fig. 1 is a vertical sectional view of a typey, writing machine with various parts omitted and showing a type action embodying the devices of the present invention.

Fig. 2 is an enlarged, fragmentary view oi the type action shown in Fig. 1 wherein certain parts are shown in their operated position for printing one of the characters on the type bar.

Fig. 3 is another enlarged, fragmentary view of the type action shown in Fig. 1 wherein certain parts are shown in a different operatedV position for printing another of the characters Vthe parts of this machine which are not shown .4;

in the present drawings and which are not neces-- sarily modified by the present invention.

The illustrated machine includes a series of type actions mounted in diierent radial planes about a common printing center, and as all of these type actions are` substantially the same, it

is only necessary for an understanding of the present invention to specifically describe the construction and operation of one of thesetype'aotions. This type action includes aV typebar 5 which is supported for endwise movement by guiding means including links I and T.' Thetwo guide links 6 and 'I are pivotally connected at points 8 and 9 to the type bar 5,1andthese links extend downwardly from these points in substantially parallel relation.

The lower end of the front guide link YEis pivctally connected at IE) to the end of a stationary member I I adjustably mounted on a frame member or hanger I2 by a pin I3 and van eccentric adjusting screw I4. The lower end of -the rear guide link l is pivotally mounted at I6 on a bell crank I'I which is in turn pivotally `mounted at I3 on a shiftable arm l. The arm i9 is pivotally mounted at 2iion the lower end of a stationary adjustable bracket 2i which is mounted by pin 22 and an eccentric adjusting screw 23 on the hanger i2.

The rearward end of type bar `5 is bifurcated Awith a type block mounted on the upper bifurcated portion carrying a lower case Atype 25 and an upper case type 26, and the lower bifurcated portion is likewise provided with a vtype block n carrying a different lower case type iZ'I and a different upper case type 28. In order to selectively determine which of the types 25, 2t, 21 or 28 is printed, bell crank I'I is movable to either of two positions to select between-two characters and shitable member I9 is movable to either of two positions to determine whether the selected character is printed in its lower case or upper case form. The means for moving and holding members II and I9 in their dierent positions will later be described in detail.

The hanger I2 for each type action issupported by front and rear arcuate cross members 3a and 3|, the rear cross member 3| being provided with an upstanding comb portion for guiding the lower edge of type bar 5. The rear portion of each hanger l2 is provided with -a slot embracing a rib on cross member 3| to aiord a slight adjustment of ther hanger toward and from the printing center, which adjustment is effected by a screw 32 threaded into front'cross member 3i! and having an annular groove receiving a downwardly extending lug at the front end of hanger I2 in the usual manner. Each hanger l2 is retained in its adjusted position by a screw 33 threaded into the cross member 38 and having an enlarged head engaging the upper edge of the hanger.

The type bar receives a forward movemenrI in each instance by a pressure printing mechanism which may be the same as disclosed in the previously mentioned Patent No. 1,573,544. This pressure printing mechanism includes a sub lever 35 formed by parallel upstanding arms straddling a depending portion of hanger I2 and pivotally mounted at 36 at the lower end of this depending hanger portion. The upper end of sub lever 35 is pivotally connected at 31 to a weighted member or momentum accumulator 38, and a rearwardly extending arm 39 of the momentum accumulator is pivotally connected at 40 to the intermediate offset portion of a toggle link 4I. The lower end of toggle link 4| is pivotally mounted at 42 on hanger I 2, and the upper end of the togglelink is pivotally connected at 43 to the front end of a second toggle link V44., The second toggle link 44 is formed by two parallel strips disposed onopposite sides of the type bar 5 with their rearward ends pivotally connected at the same point 8 which joins type bar 5 with front guide link 6.

The parts of the type action are returned from actuated position to normal position shown in Fig. 1 byra contractile returning spring 46 lconnected between hanger I2 and a pivot pin 41 on sub lever 35, which pin also serves to pivotally mount a depending universal bar actuating member 48 of the usual construction. The parts of the type action are prevented from rebounding from normal position as they are returned from actuated position by toggle links 49 and 5U which operate in the manner lfully disclosed in Patent No. 1,604,640,V The rearward end of link 49 is pivotally connected at 5I to hanger I2, and the front end of link 49 is pivotally connected at 52 to the rear end of link 58 which is in turn pivotally connected at 53 to momentum accumulator 38. These links 49 and 50 are disposed in straightened reiation when the parts of the type action reach normal position as shown in Fig. 1 so that the reactive force of these parts upon being arrested in this position is directed longitudinally of this straightened toggle arrangement to prevent rebound of the parts from normal position. Y

The type bar 5 may be operated to afford substantially noiseless pressure printing through the double toggle arrangement just described by either of two key levers 55 or 56 which are connected to individually operate sub lever 35. The key levers 55 and 56 are provided with individual keys 51 at the front ends thereof, and all of the key levers pivot about a fulcrum 58 and each lever is individually returned by a spring 59 arranged in the usual manner. The intermediate portion of key lever 55 is connected by a substantially vertically disposed link 63 to an actuating lever 64 pivotally mounted at 65 on one side Vof hanger I2, and the intermediate portion of the key lever 56 is likewise pivotally connected by a similarV link 61 to another actuating lever 68 also pivoted at 65 to hanger I2Yand disposed on the opposite side thereof from the actuating lever 64. The forwardly extending portions of actuating levers 64 and 68 are provided with curved lower edges forming treads which overlie a curved tread 18 secured on the upper edge of a rearwardly extending arm 1I 'of sub lever 35.

A manual operation of either key lever 55 or 56 operates the associated lever 64 or 68 to effect a pressure printing operation of type bar 5, and this operation of the present type action does not differ materially from the ordinary Remington noisless type action disclosed in the previously mentioned Patent No. 1,573,544. When lever 54 is operated by a depression of key leveil 55, the curved lower edge of lever 64 has a rocking engagement with the curved tread member 13 to effect a changing leverage causing a rapidly accelerated movement of sub lever 35 in the usual manner. This movement of sub lever 35 operates through arm 39 to move toggle members 4| and 44 toward a straightened position as shown in Fig. 2, thereby moving type bar 5 rearwardly toward the printing position. The movement of lever 64 is limited by the engagement of the rear wall of a cut out portion therein which engages the head of pin I3, and the further movement of the sub lever 35 to its position shown in Fig. 2 is caused by the momentum of the parts which causes momentum accumulator 38 to move rearwardly suiciently to operate toggle members 4| and 44 to substantially a straightline position causing the final pressure printing movement of the type bar.

When lever 64 is operated from its position shown in Fig. 1 to its position shown in Fig. 2, it will be noted that the lower pivot I6 for the rear guide link 1 remains stationary. With the pivot I 6 in the position shown in Figs. 1 and 2, type bar 5 moves to the printing position through a path which causes the lower bifurcated portieri of the type bar to enter a type guide 15 positioned so that type 21 is pressed against a work sheet which may be carried by a platen 1 6. The type guide 15 and platen 16 may be of any suitable construction such as ordinarily employed in a machine of this type, but in this instance the platen 16 does not have a case shifting movement.

When lever 68 is operated by a depression of Vkey lever 56, type bar 5 is moved toward platen 16 in substantially the same manner as when lever 64 is operated, but in this case the operation of lever 68 causes pivot i6 to move downwardly and guide type bar 5 through a path causing the upper bifurcated portion thereof to enter type guide 15 which is positioned so that type 25 is pressed against the work sheet carried by-platen 16. In accordance with the present invention. the means for causing pivot I6 to move downwardly by the operation of the lever 68 includes two normally straightened toggle elements so arranged that a particularly desirable operating characteristic is produced.

Referring to Figs. 1 and 2, a rearwardly extending arm 18 on lever 88 is pivotally connected at 19 to a link 88, and the other end of link 88 is pivotally connected at 8| to an arm 82 which is pivotally mounted at 83 on the stationary hanger I2. The forward end of arm 82 is pivotally connected at 85 to a link 86, and the other end 4oi link 86 is pivotally connected at 81 to an arm 88 also pivotally mounted at 89 on hanger I2. 'Ihe lower end of arm 88 is pivotally connected at 92 to the forward end of a link 93 which is in turn pivotally connected at 94 to bell crank I1 which supports the rearward guide link 1.

An operation of lever 68 moves these levers and links from their normal position shown in Fig. 1 to their position shown in Fig` 3 wherein .movement vrofrthese parts vis arrested by vthe .en-

gagement vof the wall of a cut out portion vin ythe upper end of arm 88 with a stationary pin -91 carried by hanger I2. The movement `of bell crank "I1 thus effected Eby the operation of lever 68 causes `pivot I6 to move downwardly to aposition wherein it is below pivot I8 so that the axes of pivots I6, I8 and 9 are substantially in alignment. This position of pivot I6 `causes the reactive forces incidental to the printing operation of type bar to. be directed substantially `against the dead center of pivot I-8 thereby veliminating the tendency lfor typebar 5 to be'displaced while printing. y

A particular feature of the present invention is the provision of connecting means between lever 68 and bell crank I'I :which includes as doulole toggle arrangement provided by arm 18, link SI), arm 82 and link 86. When Ythese parts vare. in their normal position, link 80 assumes a straightened relation to arm 'IS so that pivots 65, 'I9 and 8| are substantially in alignment, vand likewise link 85 and arm `82 have substantially a straightened relation wherein pivots 83, V33- 'and 81 are all in substantial alignment. This arrangement .affords a considerable mechanical advantage in the operation of bell crank I1 by lever 68 due to the operation of the toggle elements *IB- 33 and 82-86 from a straightened relation and due -to the arrangement of these two sets of toggle-Jelements in series whereby the leverage changing characteristics of one set of -tog'gles is amplified by the similar leverage changing characteristics of the other set of toggles. The result is that the initial movement of lever S3 eects avery slow initial movement of *bell crank II'I and the force ,required at lever 68 to effect thisinitial movement of bell crank I'I is -very slight.

The 'above result attained by the' double toggle arrangement of Vthe present invention is verydesirable in a type action of this kind lbecause the vslow initialmovement of bell crankI'I Vallows type bare to be moved rearwardly7 to apoint wherein the adjacent type 'ba-rs in their normal position do not interfere with the downward movement of the rearward end of type bar v5 vcaused by Athe movement 'of bell crank I1. It is also desirable in a type action to provide an arrangement resulting in a light initial operating iorceror ftouch .ci the type action. This result is attained in the present arrangement by the light "ini-tial. force required to-move bell Vcrank I'I Vby lever 6'8 so that the force required to operate the type bar toward its printing position and to shift bell crank I1 by operation oi lever 6.8 is not appreciably greater initially than the operation -of the type bar by lever E4.

The double `toggle :arrangement associated with lever E28 alsoiV has the very importantfunction 'of holding bell crank vI'I against movement :about its pivot I8 during operationA of lever 64. :When lever (i8V is in normal position 'as' shown in Fig. l, pivots S'I, S5 and 83 are in substantialxalignment so that any reactive force tending to kturn bell crank I? about its pivot I3 is transmitted to lever 88 through link 93 and this force is directed substantially against the dead 'center of :pivot 83. Likewise, pivots BI, 'I9 and Iik are. in 4substantial alignment so that if any reactive force iisappl'ied to llever 82, this force' -is directed 'substantially against the. dead center ofpivot 65.- ;Inthis manner,l there is a double-assurance `that thereactive forces incident to the printing operation of the type bar upon operation-ofv lever `64 cannot cause -displacementof bell crank I-'I about itspvot Iii;A

.The present type actonvincludes Athe usual interlocking arrangementv for insuring that vlever 68 is in its normal position when the type bar is actuated by lever Referring to Fig. 2 this `arrangement includes a crank member IBI] pivot- Vabout its pivot IIII to a position wherein a forwardly extending arm |05 engages vthe upper vedge of arm 'I3 thereby insuring that lever 68 and parts connected thereto are in normal' position when type bar 5 reaches its printing position by actuation of lever 655. Thus, the twolevers 64 and t8 cannot receive an Veffective.simultaneous operation, and it is insured. that the double toggle arrangement associated vwith lever 6B is :in straightened relation to hold pivot I6 in norma-1 position with relation to pivot I8 when the type bar reaches its printing point by operation of lever 64I.

In the presenttype action, pivot I6 is selectively positioned either as shown in solid lines in Fig. 2 or as shown in solid lines in Fig. 3 according to whether key lever or 5e is operated and thereby selectively prints from either lower case type 21er lower case type 25. In accordance with the present invention, the platen I6 does not receive a caseshifting movement, and pivot I6 is shifted to either of two additional positions shown by dotted lines in Figs. 2 and 3 to allow printing to be effected from eitherof the upper case typ-es 2d or 25 rather than the lower case types 2T or 25. Thus, means are provided in the present machine -for shifting lever I9 which pivotally supports bell crank I'I between its solid line and dotted line positions shown in Figs. 2 and 3, which means also shifts type guide 'I5 between its solid line and dotted line positions shown in Fig. 1. f

Referring to Fig. l, type guide I5 is mounted at II Il on a shiftable frame III. The frame III `is guided by means not shown which may be suitably arranged to afford substantially vertical shifting. movement of type guide I5 and to retain the type guide and shiitable 'frame against displacement inevery other direction. The rearward end of an extension H2 of the arm I9 asso-V ciated with each type action is received between arcuate plates II3 suitably secured in vertically spaced relation at the lower portion of shiftable frame III. In this manner, the shifting movement of type guide I5 and frame III causes a pivotal movement of arm I9 of each type action about pivot 2S so that the pivots IS 01 vall the type actions in the machine receive a simultaneous shiftingv movement between the solid line `and dotted line positions shown in Figs. Z'and 3.

Suitable stop means may be employed for accurately arresting the shiftable member'l I-I in each of its extreme shifted positions, whichjstop means has not been shown in the present -instance. Various diierentV arrangements may also be provided for eiecting the shifting movement of frame I I I, the means shown in the present instance comprising a `lower extension ci the shiftab-l'e member III which .is pivotally Y,con-- .nected at H4 to a rearward extendingarm' II5 rigidly secured to a rock shaft IIS mounted by suitable bearings in the frame of the machine which has not been shown. A rearwardly extending arrn II'I secured to rock shaft III;` vcarat the upper end of a link |20 which is pivotally connected at I2| to a T-shaped arm |22 secured to a rock shaftA |23. The rock shaft |23 is suitably mounted in the frame of the machine, and the usual case shift key levers I 24 are operatively connected with the rock shaft |23. The usual shift key |25 and shift lock,V key construction |26 are provided at the forward end of each shift key lever I 24. A contractile spring |28 extends between the upper portion of the T-shaped arm |22 and a xed pin |29 on the frame of the machine, and another contractile spring |30 extends between pin |29 and a depending arm I3I secured to rock shaft I I5.

It will be clear that the spring |30 tends to move shiftable frame III and type guide 'I5 upwardly toward its dotted line position while spring I 28 acts to hold the shift key levers |24 in normal position and acts through link |20 against the force of spring |30. The spring |28 is thus provided with a greater eifective force so 'that when no downward pressure is applied to the shift key levers |24, all the case shiftable parts are retained in their downward or lower case position against the force of spring |30. However, when a downward pressure is applied to the shift key lever |24 to overcome the force of spring |28, spring |30 is effective to move the shiftable frame III and type guide 'I5 upwardly to the dotted line or upper case position. The pin H8 and slot I9 provide a one-way operative connection between the link I 20 and arm II1 whereby the downward movement of shift key lever |24 is not transmitted to arm II`| so that the shiftable frame III and parts controlled thereby are always moved by the uniform force of spring |30 regardless of the force applied to key lever |24.

Referring to Fig. 2, it will be clear that when the case shift mechanism is operated to shift lpivot I6 from its solid line position to its dotted V68 by key lever 55 will cause type bar 5 to move through a path which brings type 26 to the printing point rather than type 25 as previously described in connection with the lower solid line position of pivot I6 shown in Fig. 3. The upward shifting movement of pivot I6 in each instance causes a pivotal movement of type bar about pivot 8 so that this case shifting movement; doesnot in any way affect the position and operation of the toggle arrangement connecting sub lever 35 with the type bar. It will also be clear that this case shifting movement of pivot I6 causes a pivotal movement of link 93 about its pivotal connection 92 with arm 88 so that the position and functioning of the toggle 'IS- 80 and 82-85 are not in any way affected by this case shifting movement.

A type action has thus been provided wherein the guiding means, or the guide link 1 and supporting means I1, for the endwise moving type bar are selectively moved to one of four different positions to print from one of four different types, and the type bar is retained in -eacli of such positions against displacement by the reactive forces'incident to the printing operation.

The bell lcrank supporting member l'I-Iis vretained in either v its solid line position or its dotted line position shown in Fig. 2 against displacement during printing operation by the straightened relation of the two sets of toggle elements 'I8-80 and 82-86. Likewise, the reactive forces caused by printing operation do not cause displacement of member I1 from either its solid line or dotted line position shown in Fig. 3 due to the fact that pivot I6 is in each instance directly below and substantially in alignment with pivots I8 and 9 and accordinglyv the forces tending to displace type bar 5 are directed through link 'I against the dead center of pivot I8.

A further very important feature of the present invention is the provision of connecting means for shifting the pivot IB for the type bar guide link upon operation of lever 68 which includes a double set of toggle elements. This double toggle arrangement aifords a variable leverage wherein lthe Ainitial forward movement of the type bar is much more rapid than the initial movement of the pivot I6 so that the type bar is moved forwardly to a position wherein it may be shifted without interference with adjacent type bars before such shifting is effected by the movement of pivot I 6. This arrangement further provides a materially reduced initial force required in shifting the type bar guiding means which results in alight initial touch which more nearly equals the initial touch in operating lever 64 which does not shift pivot I 6.

In describing the present invention, attention has been directed to one specific embodiment thereof, without attempting to point out the various alternate or optional features of'construction, or the different organizations` or combinations that may be employed.- For example, the double toggle arrangement for operatively connecting the lever 68 with the bell crank I1 may be used in a typewriter arrangement wherein the platen is mounted for case shifting movement and the bell crank |'I is pivotally mounted at |84 on a stationary member in the usual manner.

In other words, the particular embodiment of the present invention has been selected to facilitate the disclosure thereof rather than to limit the number of forms which it may assume.

The invention claimed is:

1. In a typewriting machine, the combination of a type bar, guiding means for said type bar,

-a case shiftable support, supporting Ameans for said vguiding means movably mounted on said case shiftable support, a relatively fixed support, and means for moving said supporting means for the guiding means on said case shiftable support including a first arm pivotally mounted on said Xed support, a second arm pivotally mounted on said-fixed support, a link connecting said first and second arms and normally aligning with said first arm to form a straightened toggle, a third arm pivotally mounted on said xed support, a second link connecting said second and third arms and normally aligning with said second arm to form another straightened toggle, and a third link connecting said third arm with said supporting means for the guiding means 'to .afford shifting movement of the latter with said case shiftable support and relative to said third arm.

2. In a typewriting machine, the combination of a type bar, guiding means for said type bar, a case shiftable support, supporting means for said guiding means movably mounted" 'on said case shiftable support, a relatively fixedsupport, and means for'moving said supporting means for the guiding means on said case shiftable support including a first arm pivotally mounted on said fixed support, a second arm pivotally mounted on said xed support, a link connecting said rst and second arms and normally aligning with said first arm to form a straightened toggle, and means connecting said second arm with said supporting means for the guiding means to afford shifting movement of the latter with said case shiftable support and relative to said second arm.

3. In a typewriting machine, the combination of a type bar, guiding means for said type bar, a case shiftable support, supporting means for said guiding means movably mounted on said case shiftable support, a relatively fixed support, actuating means for said type bar including two independently operable levers pivotally mounted on said fixed support, an arm pivotally mounted on said iixed support and disposed transversely of said levers, a link connecting one of said levers with said arm and normally disposed in alignment with the lever to form a straightened toggle, and means operatively connecting said arm with said supporting means for the guiding means to afford movement of the latter with said case shiftable support and relative to said arm.

4. In a typewriting machine, the combination of a type bar, a case shiftable support, a type bar supporting and guiding means movably mounted on said case shiftable support, a plurality of aotuating means for said type bar, and toggle members connecting one of said actuating means with said type bar supporting and guiding means to move the latter on said case shiftable support upon operation of the type bar by said one of the actuating means, said toggle members being disposed in straightened relation in the normal position of said one of the actuating means to hold said type bar supporting and guiding means against movement on said case shiftable support during operation of the type bar by the other of said actuating means.

5. In a typewriting machine, a series of endthrust type bars, a pair of guide links `pivoted at one end to each type bar at spaced points' along the length of the latter, means =pivotally supporting each pair of guide links at the other. end thereof, the means supporting one guide link of each pair being movable, case shifting means for simultaneously shifting all of said means movably supporting one guide link of each pair, and actuating means for each type bar including toggle members for holding said means movably supporting one guide link of each pair against movement relative to said case shifting means regardless of the shifted position thereof.

6. In a typewriting machine, the combination of a type bar, pivoted guide links for said type bar, a case shiftable support, a bell crank having one arm pivotally connected to one of said guide links, means pivotally mounting said bell crank on said support for movement from normal position thereon to a position wherein the pivots of said guide link are in substantial alignment with the pivotal mounting means for the bell crank, and means for causing said movement of said bell crank on said support including toggle members disposed in straightened relation in the normal lposition of the bell crank.

7. In a typewriting machine, the combination of a type bar, pivoted guide links for said type bar, a case shiftable support, a bell crank having one arm pivotally connected to one of said guide links, means pivotally mounting said bellv crank on said support for movement from normal position thereon to a position wherein they pivots of said guide link are in substantial alignment with the pivotal mounting means for the bell crank, and means for causing said movement of said bell crank on said support including toggle members disposed in straightened relationin the normal position of the bell Icrank and link means -between said toggle members and said bell crank for affording shifting movement of said bell crank with said case shiftable support Without moving said toggle members. 5

8. In a typewriting machine, the combination of a type bar, printing keys, means for connecting each of said keys With the type bar, a case shiftable support, a type bar supporting member movably mounted on said case shiftable support, and toggle members for holdingfsaid type bar supporting member against movement relative to said case shiftable support during operation of the type Ibar by one of said printing keys.

9. In a typewriting machine, 'the combination of a type bar, -printing keys, means for connecting each of said keys with the Ltype bar, a oase shiftable support, a type bar supporting member movably mounted on said case s'hiftable support, and toggle members controlled by one of said printing keys Vfor holding said typfe bar supporting member against movement relative to said case shiftable support during operation of the type bar by the other of said printing keys.

l0. In a typewriting machinaithe combination of a type bar, a case shifta-ble support, `type bar supporting means movably mounted on said `case shiftable support, actuating means for said type bar, and toggle members controlled by said actuating means for normally holding said type bar supporting means ragainst movement relative to said case shiftable support.

11,. In a typewriting machine, the combination of a type bar, a case shiftable sup-port, type bar supporting means movably mounted on said case shiftable support, actuating means for said type bar, and toggle members connected between said actuating means and said type bar supporting means and arranged to assume a substantially straightened relation When said actuating means is in normal position regardless of the position of said case shiftable support.

12. In a typewriting machine, the combination of a type bar, tWo printing keysw for individually operating said type bar, a movable type bar supporting and guiding means, and -tWo sets of normally straightened toggle members arranged in series between one of said printing. keys and said type bar supporting and guiding means for moving the latter with increasing acceleration upon operation of said one of the printing keys and for holding the type bar supporting and guiding -means against movement upon operation of the other of said Iprinting keys.

RUSSELL G. THOMPSON.

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