US2204248A - Typewriting machine - Google Patents

Description

June 11, 1940. w. A. DoBsoN TYPEWRITING MACHINE Filed Aug. 5, 1936 4 Sheets-Sheet l Nm mw R. Nm zz ATTORNEY June 11, 1940. w. A. DoBsoN 2,204,248

TYPEWRITING MACHINE Filed Aug. 5, 1936 4 Sheets-Sheet 2 W- y ZI'NVENTORz June 11, 1940. W A, DOBSQN 2,204,248

TYPEWRITING MACHINE Filed Aug.` 5, 1956 Smets-Sheet i5 INvENToR= June 4l1, 1940.

w. A. DoBsoN 2,2045248 TYPEWRITING MACHINE Filed Aug. 5, 1936 4 Sheets-Sheet 4 TToR N EY i Patented June 11, 1940 i striking type-bars.

This invention relates to portable typewriting machines, having rearwardly and downwardly In portable machines, simplicity, ease of operation, lightness, compactness, cheapness, durability and attractiveness are de- The key-levers are commonly vfulcrumed at their rear ends, and various ways have been suggested to connect the downwardly-moving keys to the rearwardly-swinging type-bars. There may be employed levers, or key-mounts, which do not extend rearwardly beneath the typebar segment. It is one of the aims of this invention to make simple, roomy, durable, inexpensive type-actions having short key-levers in such a manner that'the dip of the keys may be reduced, and also rendered uniform, while the types are caused to strikeeiiiciently, and without incurring' harshness of key-touch at either beginning or end of the printing stroke.` It is an aim of the invention to provide ample room, or to provide amplevspace for vaccommodation of the various members of the type-actions, the same being specially constructed with this end in while attaining simplicity and low cost.

It has been proposed toV employ bell-cranks between the key-levers and the type-bars, each crank having a short horizontal arm 'for keyoperation, and a short vertical rearwardly-moving arm for swinging its type-bar, but the shortness of these arms is objectionable. vIt is an aim of the invention to produce a satisfactory machine, with little or no tendency to binding of the parts, and no diiculty in making connections, and to avoid the necessity of employing aids or auxiliary devices, and avoid intricacy and close assembling of mechanism, so as to minimize the diiculty of manufacturing and repairing. Itis an aim to avoid wear that would arise from the transmission of heavy power by meansof small levers, but Vto provide room for `transn'iitting levers of `ample length and strength.

It is an aim to provide ample size not 'only fo the power-transmitting sub-levers, l but also an ample length'for the depressible key-levers themselves, and especially to avoid canting the keys down excessively at the printing strokes, and to improve the key-touch.`

The invention permits a reduction in of key-stroke, thus lessening the canting eiect upon the key.` Bothy the` ample-length key-levers and the ample-length sub-levers are made to operate in the'space orv r'oom under the inclined type-bars and back of the keys,'so that the need of employing short-armed bell-cranks m UNITED STATES PATENT OFFICE f TYPE'WRITING MACHINE William A. Dobson, Wethersfield, Conn., Vassignmto Underwood 'Elliott Fisher Company, New York, N. Y., a corporation of Delaware Application August s, 193s, serial No. 94,329

(c1. 1er-2s) Cam-bearing sub-levers have veach a semi-circular scooped-out 'cam-face or edge, engageable by a drive `pin or wrist on the key-lever.

7 There are four kinds of sub-levers, one kind for each key-bank, the driving pins being in- 5 dividually located upon the key-levers.

4Other features and advantages will hereinafter appear.`

In the accompanying drawings,

`Figures 1, 2, 4, 5 vand 6 show `key-levers at the 10 middleportion of ther system, connected to typebars having relatively short swings.

Figure 1 is a sectional central elevation of a portable typewriting machine embodying the f present improvements, showing key-levers and type-bars, in normal positions.

` Figure 2 corresponds with Figure 1, but shows 4a key of the rear bank depressed, and its type-bar` swung to the platen. l

Figure 3 is a. sectional plan of the type-actions', 20

vwhichinclude horizontal parallel rearwardly-extending `key-bearing depressible levers, of such shortness that they terminate forwardly` of the type-bar segment and rearwardly of the types at Figure l, these levers being fulcrumed at about mid-height ofthe machine; The sub-levers of Figure 3 are shown mainlyin section, and they are operated by pins that project from the key-- levers to suit individual operating cams that are formed on the sub-levers.

Figures 4-10 illustrate nearly similar cams formed upon the Arear edges of the sub-levers, and show the'different positioning of the Cams'and also therdifferent positioning of the drive-pins that project from the sides of the key-levers to operate said cams. i

Figure 4 shows in full lines a centrally-disposed key-lever of the second bank, depressed about the common fulcrum-rod, andalso the form of cam that is generallyused for the .third row or set of 40 key-levers. This gure also shows in dotted lines an operated'position of one of the key-lever actions at the sides of the system.

Figure 5 corresponds with Figure 4, except that it shows the keys and levers in the third row. A

.Figure Gis also similar to Figure 44, but shows a depressed iirst-bank key at the middle of the keyrowfin full lines, While also showing in dotted lines an outer key-leveraction.

Figures 7, 8 and `10 show key-levers at the extreme sides of the system. These are connected to the type-bars having the longest swing.

Figure 7 corresponds with Figure 5, but shows 1 an extreme side key-lever of the third bank,

tion of the extreme outside key-action shownlin,

Figure 7, while also showing in dotted lines the operated position of a key-action at the middle portion of the machine.

The type-bar segment 20 inclines forwardly andv downwardly from the platen 2 Il to the bottom* of the machine, and the types* 22 ystrike upon the front top side thereof. The type bars 234v normally lie in positions inclined upwardly and forwardly from their pivots to the top of 'the' machine. g. f Operating links 24 reach forwardly from the lower ends of the type bars, the rear ends; of the links being pivoted to the type` bars at 25, the pivots lying in an arc that inclines upwardly and rearwardly. The ,linksA extendforwardly, and their front ends form a straight horizontal transverse row, occupying nearly the same levell as the pivots 26 of the middle type bars. These links are pulled forwardly tooperate the type bars, by means of pendent swinging levers 21,- which are directly engaged by the key levers 28, 29, 3l),` 3 l, in

four banks. Y

The levers, bearing the keys 320m their forward ends, swing down about their rear ends, being all mounted upon a transverse, level fulcrum-rod 33. This fulcrum-rod 33 `crossesthe machine beneath the forward portions of the forwardly and upwardly inclined type-bars 23, and so said fulcrum rod `may be placed so far back-as to afford ample length for the key-levers, even though the keyboard `islarranged close ,to the types. .f

When a key is depressed,jits pendent sub-lever 21 is forced to swing forwardly. This result is attained by a novel construction, that is,by placing the sub-lever pivots 34 above the key-levers, and by having the sub-leversextend down from their fulcrums past and between the-key-levers, the crossing occurring at=a -point between the key 32 and the key-lever fulcrum .rod 33; the keylevers being of the second order. l

The downward movement of the key lever is caused to give a forwardI swingtothe pendent sub-lever, by means of acam 50, There are illustrated four shapings of cams, viz., `a different shape for every row of keys.. The shapings are numbered 35, 3S, 31,w 38. 1,

Each cam is formedupon the rear edge-or border of its pendent sub-lever21, and inclines downwardly and rearwardly;v and it is engaged by a wrist or drive-pin 44D provided upon the adjacent key-lever. v. v

Room, may thus be econornized by bestowing in the space below the front end portions of the type-bars, both the fulcrurnedrear portions of the ample-length key-levers and the pendent cammed long sub-levers. vThe sub-levers may be made duplicates, the' cams however being varied for each of the four key-rows 'as'shown at 35, 36, 31, 38, Figure 9, and'hung on straight rod 34. l The framing of the machine 'may include sidewalls 4l, 42, which are joined by a cross-bar 43 at the top of the machine, just back of the keyboard. This cross-bar carries the fulcrum rod 34, and may be vertically slotted at 44 to guide tops of the pendent sub-levers. The level of the bar may be a little below the top level of the rear bank of keys, and the'casing of the machine may include a top plate 45 fastened down upon the cross-bar 43, and serving as a dust-cover for the slots 44. This cover plate 45 may serve to dust-proof the key sub-levers and their pivots, and may 'also afford on its rear edge a mount for a type-bar rest 45a.

The sub-levers 21 at their lower ends may be guided in a comb 46, underlying the links 24 that operate the type bars.

Upon the front face of said cross-bar 43 may be mounted a guide-comb 41 for the key-levers,

which 'at their rear ends are worked in slots 48 4cut in a transverse bar 49, joining the side walls tion; the descending finger being apt to slide off from the front of `the slanting key, and to strike keys in the next forward row.

In such machines the keys usually dip about ve-eighths of an inch, thus accentuating the objectionable inclination due to the shortness of the lever.

This objection is overcome by the present invention in making the type-bars so short and light that they may be actuated efficiently by considerably `reduced dip of thekeys, say 1%; of

an inch, so that the short levers, in the rear bank, do not have to dip to such an angle as to give them an objectionable inclination at the bottom of the stroke.

The levers are made to extend back from the f vkeyboard and underlie the type-bars, so as to permit ample lever length without lengthening the machine or augmenting its height. The levers are pivoted at about mid-height of the machine, nearly on a level with the keys in the loW-. est bank, so as to avoid undue forward movement of the descending key.

In the present invention, the keys have longlevers and relatively small angular dip, this being due partly to the relatively long key-levers, and

partly to a moderate depth of stroke.

The downward thrust of the second-order key-lever which extends forwardly from its fulcrum: about midway of the length of the type-bar system, is caused to give a forward swing to the pendent sub-lever 21 (of the third order), by simple and readily formed and inexpensive cam means, the cam being formed about midway of the height of the relatively long sub-lever (which extends from top to bottom of the machine), and therefore not subjected to unduly heavy thrust or wear. There is obtained uniformity in the depths of strokes for all the keys, notwithstanding differences in the length of strokes of the type-bars,` and differences in the lengths of the key-levers in the different banks.

The cam 58 is in the form of a curved notch in each Ysub-lever 21, extending downwardly and rearwardly. Key-lever drive-pin 40 runs on the rear edge of the cam, to press the sub-lever for-r wardly, Figure 2.

To soften the touch of the keys, the inclined initial portion of each cam is made to diverge but a little from the curved downward and forward path of the drive pin 4|) on the key-lever, the pin being at a higher level than the keylever fulcrum 33 and forward thereof.

.The cam continues to curve downwardly and rearwardly so as to accelerate the speed of the type-bar, thereby providing a shallow key stroke, and avoid jar to the operators finger at the moment of the type impact, Figure 2.

The driving pin 40 first contacts with an easy angle of the cam 5|); in other words, the direction of the cam nearly coincides with that of the descending drive pin. The cam is inwardly curved so that the leverage of the key upon the type bar is gradually decreased to a minimum, and hence the momentum of the operator's hand is gradually absorbed during the concluding portions of the key-stroke, and the hand is therefore brought to rest without subjecting the finger to shook. Hence the dip of the key is made substantially less than was heretofore considered practicable. This avoids undue inclination of the key at the bottom of the stroke, as hereinbefore explained, and also makes it practicable to have the key-levers so short as to permit them to be fulcrumed in a transverse row between the type-bar fulcrums` and the types, close up to and under the type-bars, and nearly level with all the keys, gaining the several advantages mentioned.

While the bottom portion of the cams curvature seems to be abrupt in normal position, still it will be noted that as the sub-lever swings forwardly, the cam becomes more favorably inclined, so that the depth of key stroke may not be too much shortened.

The angle through which a key drives a sublever, depends partly upon the position of the driving-pin relatively to the cam. The pins are shown placed in different individual locations upon their levers. The lower the mounting of the pin, the nearer it will be to the cam, and the greater will be the swing of the sub-lever at the key stroke.

lThe pins may be placed so as to give the keys substantially uniform strokes.

The sub-levers at the sides of the system have the greatest throws,` and each key-lever at the sides of the system has its pin placed accordingly, so that a short downward throw of the pin will effect great swing of the ysub-lever, to gain uniformity cf key stroke all over the keyboard.

`The cams in each row are substantially alike, but different from those in the other rows, Figure 9. The drive pins in each key-lever row may be in different individual positions, whereby each key may give a different length of l vibration to the sub-lever, to compensate for the different throws of the type-bars, and also to compensate for the dilerence in length of the key-levers in the several rows. The key-levers being of different lengths in the four rows, give the pins dierent lengths of stroke in the different rows.

The resistance to the finger touch may be practically the same for all the keys, including those at the sides of the system, this result being gained by using the four forms of cams or curved slides on the sub-levers, each kind having a differently placed camming surface.

The key-levers, in the rear row 3|, have the greatest angle of stroke. Accordingly, the sublevers that belong to this top row of keys have cam surfaces extending tothe greatest distances below the sub-lever pivots, as seen at 5|, `Figure 9. Hence the long stroke of the key-lever 3| effects the requisite short stroke `of the sub-lever 2T, Figure 2.

Another kind of cam bearing edges, for operation by nearly all the thirdrow of key-levers 3U, give their pins 40 shorter strokes than do the l rear levers 3|, and hence the sub-levers 21 have their cams a little nearer to the pivot, as at 52, Figure 9.

Most all of the key-levers 29 in the second row have still less angular movements, their pins 48 for their arc being placed higher, and their subelevers have the cams a little nearer to the pivot, as at 53,

The key-levers 28 in the front key-row operate with a small angular motion, and are effective to operate their type bars with the same depth of key stroke, -19-5 of an inch for all keys. The sub-levers for these key-levers 28 have their cams placed the highest, as at 54, Figure 9.

The drive pins are arranged differently for each key-lever, so as to compensate for different positionings of the cams, different angular vibrations of the key-levers, dierent lengths of the type-bar strokes, etc.

There is a practically uniform touch of the keys, accomplished with the use of a minimum number of varieties of cainmed sub-levers.

By means of inexpensive compact springs 55, one for each key, it is contrived to keep the drivepin or wrist |50 in contact with the cam 59 on the rear edge of the sub-lever, and also to return both the sub-lever and the key-lever to normal positions. For this purpose each spring 55 is tensioned to extend between the lower portion of the sub-lever, and an ear 5t that drops from the .J

fulorum-portion of the key-lever. The spring thus keeps the sub-lever under constant rearward tension, for returning it to and keeping it in normal position, together with the type-bar that is linked thereto; and the spring also lifts the key and holds it up.

In order to provide a light key-touch, notwithstanding the very shallow dip of the keys, the relative location of the individual driving pin to its described cam becomes important.

On each row of keys, the shape is the same, 4but the cam-shape for each row is different from that for the other rows.

The downward stroke of the driving pin is longest for the shortest key-levers, viz., those in the top row. The driving pins in the next iern ward row have shorter strokes; those in the next-to-front row still shorter; and those in the front row have the shortest strokes.

In lproviding for compactness, the outside typebar actions need to receive more motion to swing them to the printing point, because the outside type-bars recede farther from the platen than do the middle type-bars. The locations of the key-lever drive-pins are such as togive the neces- 'i sary increase ci motion to the outside bars, without making a new and diiierentiy designed cani-- bearing. vIn some cases, an extreme side sublever may have a cam of the saine contour and location as that normally employed in the next one kind of cam-bearing sub-lever throughout each key-bank, are avoided by using at the extreme sides of the second row 2S of the oamming sub-levers, a sub-lever like those in the first bank 28. Then by placing the drive-pin in proper location upon the extreme side-lever in the second bank 29, harshness of touch is avoided. See Figure 8.

For the extreme outside actions of the third key-bank, the substitution of cam sub-levers like those common in the second bank, give satisfactory results. See Figures '7 and l0.

The substituted cams, although having a slower angle, give the right amount of motion because the cam is nearer to the fulcrum, and gains greater leverage.

Each cammed sub-lever at its lower end swings to an increased extent for the outside action, but the four kinds of cam levers give very satisfactory results, in the described arrangement.

The locations of the pins upon the key-levers determine the amount of swing received by the cammed sub-levers, all of which may have equal length, and need not be bent.

The cams 38 in the fourth or top row are all alike.

Of the next to top row, the nine center cams 31 are alike.

The two end cams in the third row (see Figure '7) are the same as the nine center ones 36 in the second row.

The nine center ones on the second row are alike.

The two end cams on the second row (see Figure 8) are the same as the center ones on the first or bottom row.

Those in the bottom row are all alike.

The two key-levers at each side of the system have pin locations which are different from those of all other key-levers.

The dip is uniform.

The type bars may be duplicates, at low cost, the pivot being in the same location on every bar.

The type-bar operating links 24 may converge from the sub-levers to the type-bars, and the heavy links at the sides may be thinned for clearance. At their forward ends the links may be detachably hooked into the pivot holes in the sub-levers.

The swing of the middle type-bars may be say degrees, and the outside bars 112 degrees.

The movements of the links 24 and sub-levers 2l vary accordingly. A universal bar 51 of the ribbon vibrating and letter feeding mechanism, mounted on arms 58 rising from a rock-shaft 59, may be operated by front bendable fingers 60 formed on the sub-levers 21. To compensate for the differences in swinging movements of sublevers 2l, the universal bar may be bow-shaped,

` to permit the side sub-levers to have lostl motion,

to provide for uniform strokes of the universal bar 51.

The lost motion decreases from the sides to the middle of the system, and thus the stroke of the universal bar will be substantially uniform for all keys.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim:

1. In a light-duty typewriting machine having a system of pivoted type-bars and a platen relatively shiftable in oblique forward and backward direction, said platen being at about the top of the machine, a type-bar mounting segment inclining forwardly and downwardly from the platen and extending about to the bottom of the machine, the type-bars normally inclining upwardly and forwardly from their pivots about to the top of the machine and striking downwardly and rearwardly upon the platen, a keyboard having several transverse rows of keys, key-levers of the second order carrying said keys at their forward ends and fulcrumed at their rear ends, a fulcrum-mount for said key-levers extending transversely of the machine just below the typebars and forward of the type-bar pivots, the type-bar system overlying said mount, a system of pendent sub-levers, a fulcrum-mount for said sub-levers extending transversely between the key-board and the type-bar system and arranged in the upper portion of the machine, said sublevers being of the third order dependent from said mount, the sub-levers hanging between the key-levers and extending about to the bottom of the machine, and links reaching from the lower ends of said sub-levers rearwardly to said typebars, each key-lever having between its ends a driver, and each sub-lever having a rear-edge cam which is inclined at an acute angle to the downward path of said driver, to enable the downward movement of the key-lever to effect a forward swing of the sub-lever about its pivot, to drive the type-bar to the platen.

2. In a light-duty typewrting machine having a system of pivoted type-bars and a platen relatively shiftable in oblique forward and backward direction, said platen being at about the top of the machine, a type-bar mounting segment inclining forwardly and downwardly from the platen and extending about to the bottom of the machine, the type-bars normally inclining upwardly and forwardly from their pivots about to the top of the machine and striking downwardly and rearwardly upon the platen, a keyboard including several transverse rows of keys, key-levers of the second order carrying said keys at their forward ends, and fulcrumed on the machine at their rear ends, a system of pendent sublevers of the third order fulcrumed at their upper ends and extending substantially from the top to the bottom of the machine to cross said key-levers intermediate the ends thereof and extend substantially below same, links reaching from the lower ends of said sub-levers rearwardly to the type-bars, and below the type-bars and key-levers, and means for transmitting the motion of each of said key-levers to the corresponding sub-lever, effective at the region of intersection of the respective levers, whereby to effect the forward swinging of the sub-levers to actuate the type-bars by depression of the key-levers, said transmitting means comprising a campresenting an arcuate surface on each sub-lever and a pin on each key-lever engaging said cam to swing the sub-lever in actuating the type-bars, said cam having a surface of gradually decreasing inclination, the location of the key-lever pin along the cam surface being varied for the keylevers of the respective key-rows to thereby vary the effective throw of each cam to suit the associated type-bar, notwithstanding a uniform stroke of the key-lever.

3. In a light-duty typewriting machine having a system of pivoted type-bars and a platen relatively shiftable in oblique forward and backward direction, said platen being at about the top of the machine, a type-bar mounting segmentinclining forwardly and downwardly from the platen and extending about to the bottom of themachine, the type-bars normally inclining upwardly and forwardly from their pivots about to the top lof the machine and striking downwardly and rearwardly upon the platen, a keyboard including several transverse rows of keys, key-levers of the second order carrying said keys at their forward ends, and fulcrumed on the machine at their rear ends, a system of pendent sub-levers of the third order fulcrumed at their upper ends and extending substantially from the top to the bottom of the machine to cross said key-leversV intermediate the ends thereof and extend substantially below same, links reaching from the lower ends of said sub-levers rearwardly to the type-bars, and below the type-bars and key-levers, and means for transmitting the motion of each of said key-levers to the corresponding sub-lever, effective at the region of intersection of the respective levers, whereby to effect the forward swinging of the sub-levers to ac'tuate the type-bars by depression of the key-levers, said transmitting means comprising a cam presenting an arcuate `surface on each sub-lever and a pin on each key-lever engaging said cam to swing the sub-lever in actuating the type-bars, said cam having a surface of gradually decreasing inclination, the location of the key-lever pin along the cam surface being varied for the key-levers of the respective key-rows to thereby vary the effective throw of each cam to suit the associated type-bar, notwithstanding a uniform stroke of the key-lever, the resistance to the finger-touch being made substantially the same for al1 keys by varying the forms of the cams for each row of keys of the key-levers.

4. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine; the typebars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and being adapted to strike rearwardly and downwardly upon the platen, a series of pendent sub-levers of the third order pivotally mounted in a transverse row adjacent the top of the machine, links extending forwardly from said type-bars to the lower ends of said sub-levers, cams on said sub-levers, key-levers of the second order directly engaging said cams and pivoted in a transverse row beneath said type-bars at vrest and above the pivots thereof to assure minimum inclination of the key-levers in depressed position, and a key-board presenting several rows of keys for said key-levers, the cams for each key-row being shaped differently from the cams of other` key-rows to obtain substantial uniformity in the depths of the strokes for all keys ynotwithstanding the differences in the lengths of the key-levers of the respective key-rows.v

5. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen 'to the bottom portion of the machine, the type-bars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and striking downwardly and rearwardly upon the platen, aseries of pendent sub-leverspivotally mounted in a transverse row on the machine, said sub-levers extending from top to bottom of the machine, links extending forwardly from said 'type-bars to lower ends of said sub-levers, and

cams formed on therear edge of said sub-levers,

inclining downwardly and rearwardly, each of said key-levers including a pin adapted to be moved downwardly by its key-lever, for engaging the adjacent cam to drive the sub-lever and typebar.

6. In a light-duty typewriting machine having a system of type-bars and a .platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the type-bars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links lextending forwardly from said typebars to lower ends of said sub-levers, a series of key-levers having keys for operating said typebars, said key-levers being of the second order and having their fulcrums immediately below and disposed about midway of the length of the inclined type-bars, and means effective to give a forward swing to the pendent sub-levers comprising cams formed intermediate the ends of the sub-levers, and drive-pins on the key-levers for engagement with saidcams, each cam being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drive-pin on the key-lever.

'7. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the type-bars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links extending forwardly from said type-bars to lower ends of said sub-levers, a series of key levers having keys for operating said type-bars, said key-levers being of the second order and having their fulcrums immediately below and disposed about midway of the length of the inclined type-bars, and means effective to give a forward swing to the pendent sub-levers, comprising cams formed intermediate the ends of the sub-levers and drive-pins on the key-levers for engagement with said cams, each cam being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drive-pin on the key-lever, the cam continuing to curve downwardly and rearwardly so as to accelerate the speed of the type-bar for the purpose specified whereby the'leverage of the key-lever upon the type-bar is gradually decreased to minimum during depression of the key-lever.

3. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the type-bars normally inclining upwardly and forwardly from their pivots to the top portion of the vmachine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links extending forwardly from said type-bars to lower ends of said sub-levers, a series of keylevers having keys for operating said type-bars, said key-levers being of the second order and having their fulcrums immediately below and disposed about midway of the length of the inclined type-bars, and means effective to give a forward swing to the pendent sub-levers, comprising cams formed intermediate the ends of the sub-levers and drive-pins on the key-levers for engagement with said cams, each cam being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drive-pin on the key-lever, the cam continuing to curve downwardly and rearwardly so as to accelerate the speed of the type-bar for the purpose specified whereby the leverage of the key-lever upon the type bar is gradually decreased to minimum during depression of the key-lever, the keys of said key-levers being arranged in transverse rows, the pins being placed in different individual locations upon their levers, the cams associated with each key-row being of substantially uniform shapes but differing from the shapes of the cams in the remaining rows whereby to obtain substantial uniformity in the depths of strokes for all keys notwithstanding the differences in the lengths of the key-levers of the respective key-rows.

9. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the type-bars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links extending forwardly from said type-bars to lower ends of said sub-levers, a series of keylevers having keys for operating said type-bars, said key-levers being of the second order and having their fulcrums immediately below and disposed about midway of the length of the inclined type-bars, and means effective to give a forward swing to the pendent sub-levers, comprising cams formed intermediate the ends of the sub-levers and drive-pins on the Akey-levers for engagement with said cams, each cam being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drive-pin on the keylever, the cam continuing to curve downwardly and rearwardly so as to accelerate the speed of the type-bar for the purpose specied whereby the leverage of the key-lever upon the type-bar is gradually decreased to minimum during depression of the key-lever, and the dip of the key is minimized and undue inclination of the keys at the bottom of the strokes is avoided, the keylevers being so short that they may be fulcrumed in a transverse plane between the type-bar fulcrums and the types, and close beneath the typebars.

10. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the typebars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links extending forwardly from said type-bars to lower ends of said sub-levers, a

series of key-levers having keys for operating said type-bars, said key-levers being of the second order and having their fulcrums immediately below and disposed about midway of the length of the inclined type-bars, and means effective to give a forward swing to thel pendent sub-levers, comprising cams formed intermediate the ends of the sub-levers and drive-pins on the key-levers for engagement with said cams, each cam being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drivepin on the key-lever, the cam continuing to curve downwardly and rearwardly so as to accelerate the speed of the type-bar for the purpose specified whereby the leverage of the key-lever upon the type-bar is gradually decreased to minimum during depression of the key-lever, the keys l.

of said key-levers being arranged in transverse rows, the pins in each key-lever row being in different individual positions, whereby each key may give a different length of vibration to its sublever, to compensate for differences in the throws of the respective type-bars, andto compensate for the difference in length of the key-levers of the several rows, and the consequent differences in the lengths of drive-stroke of the pins.

il. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the typebars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links extending forwardly from said type-bars to lower ends of said sub-levers, a series of key-levers having keys for operating said typebars, said key-levers being of the second order and having'their fulcrums immediately below and disposed about midway of the length of the inclined type-bars and means effective to give a forward swing to the pendent sub-levers, comprising cams formed intermediate the ends of the sub-levers and drive-pins on the key-levers for engagement with said cams, each cam being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drive-pin on the key-lever, the cam continuing to curve downwardly and rearwardly so as to accelerate the l speed of the type-bar for the purpose specied whereby the leverage of the key-lever upon the type-bar is gradually decreased to minimum during depression of the key-lever, the keys of said key-levers being arranged in transverse rows, the i pins in each key-lever row being in different individual positions, whereby each key may give a diierent length of vibration to its sub-lever, to compensate for differences in the throws of the respective type-bars, and to compensate for the difference in length of the key-levers of the several rows, and the consequent differences in the lengths of drive-stroke of the pins, the resistance to the finger-touch being made practically the same for all the keys by varying the curvature of the cams of each set of sub-levers associated with the respective transverse rows of keys from the sub-lever cams of other transverse key-rows.

l2. In a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the typebars normally inclining upwardly and forwardly from their pivots to the top portion of the ma- 2,204,248 vchine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links extending forwardly from said type-bars to lower ends of said sub-levers, a series of key-levers having keys for operating said type bars, said key-levers being of the second order and having their fulcrums immediately below and disposed about midway of the length of the inclined type-bars, and means effective to give a forward swing to the pendent sub-levers, comprising cams formed intermediate the ends of the sub-levers and drive-pins on the key-levers for engagement with said cams, each cam being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drivepin on the key-lever, the cam continuing to curve downwardly and rearwardly so as to accelerate the speed of the type-bar for the purpose specified whereby the leverage of the key-lever upon the type-bar is gradually decreased to minimum during depression of the key-lever, said pinsk being arranged differently on each key-lever so as to compensate for different positionings of the cams, different angular vibrations of the key-levers, and different lengths of the sub-lever strokes.

13. In` a light-duty typewriting machine having a system of type-bars and a platen relatively shiftable, a type-bar mounting segment inclining forwardly and downwardly from the platen to the bottom portion of the machine, the typebars normally inclining upwardly and forwardly from their pivots to the top portion of the ma chine and striking downwardly and rearwardly upon the platen, a series of pendent sub-levers pivotally mounted in a transverse row on said machine, links: extending forwardly from said type-bars to lower ends of said sub-levers, a series of key-levers having keysI for operating said typebars, said key-levers being of the second order and having their fulcrums immediately below and disposed about midway of the length of the inclined type-bars, and means effective to give a forward swing to the pendent sub-levers, comprising cams formed intermediate the ends of the sub-levers anddrive-pins on thev key-levers for engagement with said cams, each cani being in the form of an inward curve in the sub-lever, the initial portion of each cam being a little divergent from the downward path of the drive-pin on the key-lever, the cam continuing to curve downwardly and rearwardly so as to accelerate the speed of the type-bar for the purpose specified whereby the leverage of the key-lever upon the type-bar is gradually decreased to minimum during depression of the key-lever, the keys of said key-lever being arranged in transverse rows, the pins in each key-lever row being in different individual positions, whereby each key may give a different length of vibration to its sub-lever, to compensate for differences in the throws of the respective type-bars, and to compensate for the difference in length of the key-levers of the several rows, and the consequent differences in the lengths of drive-stroke of the pins, the downward strokes of the pins being longest for the shortest key-levers; and the key-levers in the front row having the shortest angular strokes.

lll. In a compact typewriting machine having a platen, a system of swingable type bars and a type bar fulcruming segment inclining forwardly and downwardly from the platen, the type bars normally inclining upwardly and forwardly from their pivots to a horizontally arcuate type-vend array, said type bars being adapted to strike rearwardly and downwardly on the platen, a series of sub-levers of the third order pendent from a transverse fulcrum axis `disposed substantially immediately forwardly of said type-end array, links operatively connecting the lower ends of said sub-levers to said type bars, and a system of key-levers of the second order presenting a plurality of transverse key rows, interspaced with and therefore crossing said sub-levers to extend from the key rows to a transverse common fulcrum axis disposed within the region confined by the normally inclined type bars, sub-levers and links, each sub-lever including a cam intermediate its fulcrum' end and lower end, and each key-lever having a pin engaging said cam.

l5. In a compact typewriting machine having a platen, a system of swingable type bars and a type bar fulcruming segment inclining forwardly and downwardly from the platen substantially to the bottom portion of the machine, the type bars normally inclining upwardly and forwardly from their pivots to the top portion of the machine and presenting an arcuate array of type heads at a level substantially no higher than the top of the platen and being adapted to strike rearwardly and downwardly upon the platen, a system of key levers presenting a plurality of transverse key rows substantially no higher than the level of the top of the platen, a common key lever fulcrum extending transversely of the machine and disposed forwardly of the type bar fulcruming segment in close proximity to the central type bars at rest, a series of pendent sub-levers ofthe third order having a common transverse fulcrum axis disposed just forwardly of the central type heads and reaching between and below the key levers, and a series of pull links extending forwardly from said type bars, beneath said key lever fulcrum to lower ends of the corresponding sub-levers, each sub-lever including a cam intermediate its fulcrum and lower end, and each key lever having a pin engaging said cam.

WILLIAM A. DOBSON.

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