US2268867A - Typewriting machine - Google Patents

Description

Jan. 6', 1942- w. A. GABRIELSON ETAL 2,268,867

TYPEWRITING MAcHiNE Filed June 19, 1940 4 Sheets-Sheet 1 INVENTORS W-A.GABR\ELSON E ct. MOSH ER A'r'r'oRNEY 1942- w. A. GABRIELSON ETAL 2 3 TYPEWRITING MACHINE Filed June 19, 1940 4 Sheets-Sheet 2 ATTORNEY Jan. 6, 1942- W.,A. GABRIELSON z-z-rm. 3, TYPEWRITING MACHINE Filed June 19, 1940 4 Sheets-Sheet 3 Jan. 6, 1942- w. A. GABRlELSO-N E TAL 2,263,367

TYPEWRITING MACHINE Filed Jun 19, 1940 4 Sheets-Sheet 4 INVENTORS W- A. QAB'R ELSON E.G:- MOSl-HER ATTORNEY Patented Jan. 6, 1942 4 UNITED STAT TYPYEWRITING. MACHINE 'William A. Gabriel son and Edson GQMosliier, Syracuse, N. Y; assignors to L. *0. Smith &

' Corona Typewriters, Inc.,-"S corporationof New York yraciise, N. Y., a

l A n m 1940,'seria11vol 341,250

' 7 Claims.

The invention relates to improvements in typewriting machines. I

The improvements provide a typewriting ma; chine operable to type with either of a--plurality of fontsor sets of types each ofwhich fonts or sets requires a letter spacing different from that of the other font or fonts, the letter'spacing for any single font being uniform, and the improvements also-provide for automatically conditioning the machine for properly letter-spacing the characters of any of its-several fonts or sets of types upon conditioning of the machinefor use of said font in typing. 1 The improvements also provide means whereby the changes of type fonts and letter spacing may be effected by depressing and releasing a single key.

The improvements also provide means whereby the type font and letter-space changes may made at any point in the travel of the platen carriage and with maximum-ease by a supple mental key-controlled means operable to back space the carriage a fraction only of'one letter space and hold the carriage so back'spaced during font and letter space changing operations.

The improvements also provide means for changingthe number of letter spaces per inch by means of a single key which is depressed and released to effect eachsuccessive change of letter spacing. 1

The improvements also provide means for effecting space changing by axial shift of any one of a plurality of axially registered escapement ratchet wheels of equal diameter into posi-' tion for cooperation therewith of the escapement dogs of a single dogrocker having an in-' variable throw, each ratchet wheel having a different number of teeth than the others and being geared to the platen carriage. j

The improvements are particularly useful as a whole in a machine having type bars or type carriers each bearing one type character of each of a plurality of fonts or sets of types, and wherein the change of font is effected by fontchanging means analogous to case changing means ordinarily employed in machines the type carriers or type bars of which are provided with upper and lower case characters of a type font. As an example of; the improved type of machine there is shown one wherein each type bar bears one of the characters of a font of large capitals and the corresponding character of a font of small capitals. I r I Other purposes and advantages of the invention will appear from the following description of the preferred embodiment of the invention shown in the accompanying, drawings in which: Fig. 1. is aver-tical medial longitudinal. sectional [view of the improved machine, approxi mately on the line l-l ofFig. 7, with the several parts innormal idleposition and the machine conditioned for typing with a-font of small capitals and with minimum letter spacing;

Fig. 2 is a fragmentary vertical sectional view on the'line 2-4 of Fig. 7; W 4

Figs. 3 and 4 are views similar to Fig. 2 showingjtheposition of the parts upon successive depressions of the font and space changing key,

3 and 4; I

letter-space changing means;

Fig.6 isa detail view on the line 6.6 of Fig. '7 showing Part of thebac k-spacing and partial back-spacingmeans of the machine;

. Fig. 7- is a fragmentary vertical transverse sectional view of the machine on the line 1-1 of Fig. 1;

Fig. 8 is a fra machine; and

Figs.-9 and 10 are detail views of the backspacing mechanism, showing respectively the parts in normal idleposition and as they appear at the endofan operating stroke of the backspacing pawl' or dog. I

The improvements are shown embodied in a preferred form thereof inv-a known L C Smith typewriting machine, only so much of which known machine is shown asis necessary for an understanding of .the improvements;

The machine; isprovided with the usual arcuate set of: type bars I!) pivotally mounted inthe usual way OIIthG usual arcuate type ha segment I! to strike-rearwardly to-theplaten 12. Each type bar-isoperable as usual by one of the usual series of key actions. 'Each, individual key action comprises a key'lever l3 carrying an appropriate'character-key Hand' fulcrumed at its rear end on'the usual fulcrum bar IS on the mainframe 16 of the machine. The key levers [3 are returned against the usual stop H on the main frame by the usual return springs l8 an-' chored to the key levers and main-frame. Upon -depression ,-of any character key its associated type'bar is-swung rearwardly to printing position by the usual sub-lever l 9 of that key action,

which sub-lever is connected as usual v to the associated typebar by a link 20 and to the associated keyilever by a link 2|. The sub-levers I9 55 are fulcrumed at 22,0n the main frame l6.

saidkey being fully depressed in'each of Figs.

Fig. 5 is a detail top plan view of a part of the gmentaryrear elevation of the v On the printing stroke of each type bar the associated sub-lever I9 moves rearwardly the usual arcuate universal bar 23 of the machine, said universal bar including a central rearwardly extending stem 23 connected to the tail or lower end of the usual escapement dog carrier or dog rocker 24 of the machine to rock the rocker about its pivotal axis 25 on the main framework. The dog rocker and universal bar are restored to normal position on the return stroke of any actuated type bar by the usual dog rocker return spring 26. The usual dog rocker stops 2! and 28 on the main frame limit the extent of motion of both the dog rocker and universal bar. The dog rocker carries at its upperend; the usual escapement dogs 29 and 3|! for alternate coaction in the known manner with the teeth of an escapement wheel to letter-space the usual platen carriage 3| in which platen I2 is journalled as usual. The carriage is mounted as usual on the main frame to travel transversely of the machine on suitable ball bearings 32v and is normally urged toward the left-hand side. of the machine by thev usual escapement spring drum (not shown) on the main frame, connected with the carriage by the usual draw band (not shown).

The usual feed rack 33- is fixed to the carriage to travel therewith and meshes with the usual feed pinion 34 fixed on a feed shaft 35. The

feed shaft is journalled in a fixed bearing sleeve 36 on the main frame and is held against axial movement by feed pinion 34 and a fixed collar on the shaft.

In the improved machine the type bars carry, instead of the usual set or font of upper-case types and usual setor font of lower-case types, a set or font of types 31 such as large capitals requiring one letter spacing, and a set or font of types 33 such as small capitals requiring a lesser extent of letter spacing, the large capitals being located nearest the free end of the type bars in the machine shown. Each type bar carries two types for printing like characters of different ones of said two fonts.

In the improved machine means are provided for conditioning the machine for typing with either set or font of types and for automatically conditioning the escapement to feed the carriage letter space distances appropriate to the font of type in use.

The type bar segment H is supported onthe main frame to shift up and down relatively to the platen 2 to condition the machine fortyping with either font. To this end the segment is supported adjacent each end on the frame -by ball bearings 39 in suitable races to shift up and down and is al'so'supported to shift up and down by a pair of rock arms 40 (Fig. 7) fixed on a rock shaft 4|. Arms 40' are pivoted at 42 to the segment, and shaft 4| extends transversely of the machine and is journalled in the main frame. The up and down movements of the segment are limited by stops 43 and 44 carried by a threaded stem 45 screwed into the segment. This stem is reciprocable in an aperture 46 in a portion of frame l6 which is engageable by the stops.

Fixedto shaft 4| adjacent the right hand end of the shaft is a forwardly'extending rock arm 41 transversely through which passes a horizontall-y disposed pin or bolt 48 having a. tight driving fit in said arm or otherwise held to the arm against movement. Rigidly welded or otherwise fixed to arm 41 is an angular bracket or extension 49 to which is anchored the rear end of a This means will now'be' described.

segment lifting coiled spring 50 the front end of which is anchored to the main frame l6.

Spring 50 is adapted to raise the segment and hold stop 43 engaged with the main frame, in which position of the segment the font or set of types 38 are coactive with the platen at the printing point to print. Shaft 4| and the arms fixed thereto constitute a shift frame for the type bar segment. By pulling the segment down by rocking shaft 4| in opposition to the pull of spring 50 until the segment stop 44 engages the main frame the segment may be positioned for coaction of thefont of types 31 with the platen to print. Means are provided for so pulling down the segment and for latching it down.

A draw link 5| has its upper end loosely pivoted on bolt 48 and engaged in a slot in arm 41 (see Fig. 7) to swing about said bolt in said slot. Changes of font and of letter space extent are effected by operation of a single font and escapement changing key lever 52 bearing a key 53 and fulcrumed on the fulcrum bar I5 on the main frame. A return spring 54 connected to the key lever 52 and main frame l6 normally swings and holds the key lever 52 up against the key lever stop H. The key lever 52 is located adjacent the right hand side of the machine and has projecting laterally inward therefrom about midway the ends of said lever a horizontal stud '55 having a reduced intermediate portion constantly engaged in an up and down extending slot 56 inthe draw link 5|. In the position of the parts in Figs. 1, 2 and 7 the stud 55 is at the bottom of slot 56.

In Fig. 3 key lever 52 is shown pressed down to shift the segment and its shift frame from the position shown in Figs. 1, 2 and 7 to the other operative position of the segment in which the large capital types are coactive with the platen. During the downward movement of the key lever 52 and its key 53 it will be obvious that stud 55 has pulled down draw link 5| until the segment was lowered" and arrested by stop 44. During this downward movement of the segment it will be seen that a pivoted latch lever 51 has acted on the shift frame just as the segment reached its lowest position to latch the segment and shift frame against return movement by spring 50. The key lever 52 may now return to normal position upon release of pressure on its key without releasing this latch. In so doing, the stud 5'5 rises in slot 56 but does not leave the upper end of said slot. On the next depression of the key lever 52 the latch will be released on the down stroke of the key lever as shown in Fig. 4 and on the following up stroke of the key lever 52 the segment and shift frame and latch 51 will be restored to the position of Figs. '1, 2 and 7. Itwill thus be seen that alternate changes of font are effected by alternate cycles of operation of key lever 52, each cycle of operation of said key lever comprising a down stroke and a return or up stroke of the key lever.

This is accomplished in the following manner. Latch lever 51 is an upstanding lever pivoted about midway its ends on the main frame by a pivot 58 to swing fore-and-aft of the machine. A light spring 59 anchored to the main frame and the upper arm of latch lever 5'I'normally urges the said upper arm of the lever 51 rearward. At its rear side, below its upper end, the lever 51 is formed with a downwardly facing shoulder 60. Extending upward from the rear end of shoulder 60 to the upper end of lever 51 is a rear edge portion 6| of said lever. In the position of the parts'shown in Figs. 1, 2 and '7 the latch out until the segment reaches its loWer-,

most position, and will then clear bolt 48 and permit shoulder 68 of the latch to slide over the top of'the bolt and thus lock the segment down as shown in Fig. 3 in which lever 52 is shown fully depressed. On the return stroke of this cycle of operation of key lever 52 a latch releasing dog 62 on the key lever 52 is ineffective to release the latch. During the down stroke of the next succeeding cycle of operation of the key lever 52 the dog 62 will release the latch 51 as shown in Fig. 4, and on the return stroke of this cycle of operation of key lever 52 said dog 62 will hold the latch 51 released until bolt 48 moves up behind edge 6| of the latch, after which said edge will hold the latch out until'the next succeeding cycle of operation of keylever 52.

DOg 62 is pivotally held to the key lever 52 13 which is mounted on shaft to turn therewith and to slide along said shaft. A pin or key 14 fixed in the sleeve is slidable in the keyway 68. Axial movement of the rigidly connected wheelsis limited in one direction by abutment of one wheel with collar 35 and is limited in the other direction by abutment of the other wheel with collar 69. The wheels 1| and 12 are of equal diameter. Wheel 1| has twelve equally spaced teethl coactive with the escapement dogs for feeding the platen carriage twelve letter spaces per inch, while wheel 12 has eight equally spaced teeth coactive' with the escapement dogs to feed the carriage eight letter spaces per inch, in the machine shown. When the wheels are shifted to their forward limit of sliding motion only wheel 1| is positioned for coaction therewith of the escapement dogs. When'the wheels are shifted to their rear limit of sliding motion only the wheel 12 is positioned for coaction therewith of the escapement dogs. The axial spacing of by a horizontal pivot 63 and has a forwardly I extending arm to which and to the key lever 52 is anchored a light spring 64 normally tending to hold the dog positioned as in Figs. 2 and 3 relatively to the key lever in which the other arm of the bell-crank shaped dog depends vertically from the key lever. The pendent arm of dog 62 is provided at its rear lower corner with a notch 65, and the rear edge of said pendent arm is inclined upward and forward from the notch 65 to provide a cam edge 66.

When key lever 52 is operated through one cycle to shift the segment downward and leave it latched down, the dog 62 on the down stroke of the lever moves from the position shown in Fig. 2 to that of Fig. 3 without said dog engaging a laterally projecting lug 61 formed on the lower end of latch 51 and extending toward the right side of the machine. On the return stroke of this cycle of operation of key lever 52, the cam edge 66 of dog 62 will ride up past lug 61, the spring 64 permitting the dog to yield as edge 66 rides up across lug 61 and then swinging the dog to normal position with respect to the key lever so that at the end of the key return on this cycle of operation the lug 61 will be engaged in the notch of dog 62. Consequently on the next succeeding cycle of operation of key lever 52 the dog 62 will during the down stroke of the lever throw out the latch 51 as shown in Fig. 4 and will hold the latch thrown out on the return stroke of said cycle until bolt 48 has risen high enough to engage behind the lower end of edge 6| of the latch, which edge will thereafter hold out I the latch during the remainder of said return stroke and until key lever 52 is next depressed.

The improved machine is provided with novel escapement means and means for automatically setting said escapement means for letter-spacing the carriage in accordance with the font selected for use by actuation of key lever 52, as will now be described. The feed shaft 35 of the escapement extends rearwardly beyond collar 35 and is provided with a longitudinal slot or key-way 68 from said collar to the rear end of the shaft. A removable collar 69 is detachably held on the rear end of shaft 35 by a suitable set screw 10. A pair of axially spaced escapement ratchet wheel 1| and 12 are fixedly united by a sleeve ill the wheels is such that when either Wheel is positioned in the field of action of the escapement dogs the other wheel is entirely out of the field of action of the dogs. I The united wheelsare shifted by an escapement setting train operable by font selecting movement of the segment shift frame'of the machine. A wheel shifting lever 15 extending transversely of the machine is pivoted about midway its ends on the main frame by a vertical pivot 16. 'At its inner end the lever 15 has a substantially circular head the periphery of which engages the inner faces of the two united escapementwheels, and at its outer end said lever is formed with an upstanding fork in which is engaged a pin or stud 11 extending horizontally inward from the pendent side arm of a yoke 18 loosely pivoted on a known rock shaft 19 of the known machine in which the improvement are shown embodied. Rock shaft 19 is journalled on the main frame; Collars on said shaft prevent axial movement of yoke 18. Yoke 18 has a rearwardly extending side arm which is connected by a pendent link 8| to an inwardly extending rear crank arm 82 of a fore-and-aft extending crank shaft 83 journalled on the main frame adjacent the right hand side of the machine. An

inwardly extending forward crank arm 84 of said crank shaft is connected by a pendent link 85 with bolt 48. The lower end of link 85 is pivoted on the bolt 48 between the arm 41 and 'a nut 48 This known mechanism Will of the bolt 01' pin 48. Crank screwed on a reduced threaded inner end portion arm 84 and a collar 86 on shaft 83 hold the shaft against axial movement.

The escapement wheel shifting train just described will shift wheel 1| into operative position when the segment is shifted upward, and said train will shift wheel 12 into operative position when the segment is shifted downward. The wheel shifting train will'hold the wheels in whichever position they are shifted until the segment is again shifted by the segment shifting means.

'For back spacing the platen carriage a letter space at a time the improved machine is provided with a back spacing mechanism similar to that of the known machine before referred to. now be described. A back spacing key 81 is carried by a back spacing key lever 88 fulcrumed on frame member I5 and normally held up against stop member [1 by a return spring I8 which is anchored to the key lever and to the main frame 16 as in the case of the character key levers. The key lever 88 is located adjacent the left hand side of the machine. A bellcrank lever 90 fulcrumed at 9| on the main frame has a forwardly extending arm connected by a pendent link 92 with key lever 88 forward of the fulcrum of the key lever, and said bellcrank has a pendent arm connected by a rearwardly extending link 93 with a pendent rock arm 94 fixed on a rock shaft 95 journalled in bearings 98 on the main frame. Adjacent its right hand end the shaft 95 has fixed thereto a downwardly-bowed forwardly-extending rock arm 91 the forward end of which is connected by an upwardly extending link 98 to the inwardly r leftwardly extending arm of a bellcrank 99 fulcrumed at I00 on a part of the main framework I6. Bellcrank 99 has an upwardly extending arm connected by an inwardly or leftwardly extending link IOI to the pendent arm of the back spacing pawl or dog I02, and said pawl has an inwardly or leftwardly extending arm provided with a reduced left hand end portion i02 slidably guided in a vertical notch I03 in a part of the main frame. Pawl I02 is fulcrumed at I04 on the upper end of a laterally swingable link I05 which is fulcrumed at its lower end at I06 on the main frame. Pawl I02 is formed with a cam edge I02 extending downward and rightward from the lower right hand end edge of extension I 02 of the pawl for coaction with the bottom edge of the notch I93 in the frame. A pair of teeth I0'I are provided on the upper edge of extension I02 of pawl I02 for coaction with the teeth of a back spacing ratchet wheel I08 fixed on the forward end of feed shaft 35 of the carriage escapement in the same vertical transverse plane of the machine in which the pawl I02 is located. A pawl retracting spring I09 is anchored at its left hand end to the arm I05 and at its right hand end to the main framework and normally holds the pawl retracted from wheel I08 as shown in Figs. 8 and 9 with the pawl teeth retracted from the wheel I08 and with a rightwardly facing stop shoulder I02 on the tooth-bearing arm of the pawl engaged with a stop lug I I0 on the frame IS.

The operation of this known back spacing mechanism for back spacing the platen carriage one letter space for each depression and release of the back spacing key 81 will be briefly described. Upon depression of the key 81 the pawl I02 will move leftward and its tooth-carrying end will rise to engage its teeth with the teeth of wheel I08. As the pawl continues to move from the position of Fig. 9 to that of Fig. 10 it will turn wheel I08 clockwise and thus drive the carriage backward or toward the right far enough to back space the carriage one letter space or tooth space of either of the wheels II and I2. Before the carriage can be driven further the cam edge I02 on the pawl rides far enough upward and leftward on the bottom edge of notch I03 to jam lock wheel I08 as shown in Fig. 10. The use of this known back spacer to back space the carriage one letter space at a time irrespective of whichof the wheels II and-I2 is in operative position is feasible because the known back spacer, as is common in the art, is made to drive the carriage backward materially more than one but less than two letter spaces before jamming. Thus a back spacer with the conventional partial overthrow for wheel 1I may be used to back space wheel I2 also a full letter space at a time.

In the improved machine novel means are mally spaced provided for facilitating the shifting of the escapement wheels II and 12 and for holding the carriage against leftward movement durin shifting of the wheels, thus making it possible to easily shift the wheels and to do this at any point in the travel of the carriage. This improved means includes utilization of the known back spacing means.

An auxiliary fractional back-spacing key III is carried by an auxiliary fractional back-spacing key lever II2 provided adjacent the left hand side of the machine alongside the main back spacing key lever 88. Said key lever H2 is fulcrumed on member I5 and normally held against stop I1 by a return spring I8 as in the case of the character key levers I3 of the machine. Forward of shaft 95 and parallel thereto a horizontal rock shaft II3 extends transversely of the machine and is journalled in bearings II4 on the main frame. Fixed on shaft II3 near the left hand end of the shaft is a forwardly and downward extending tappet .arm II5 having at its free end a tappet lug IIG underlying and norbelow the key lever II2 to be engaged by the latter after a substantial downward movement of key lever II2 but before said key lever reaches the limit of its downward movement and prior to jamming of the back space pawl as hereinafter more fully described. Shaft II3 has fixed thereto a pendent rock arm III connected by a rearwardly extending link I I8 to the downwardly bowed part of the forwardly extending and downwardly bowed arm 91 on shaft 95, the point of pivotal connection of link III! with arm 91 being shown at H9 in Fig. 6. If desired, a supplemental return spring I20 for the back spacing mechanism may be anchored to the main frame I6 and to a fixed rock arm I2I extending forward from shaft I I3.

When it is desired to change type fonts and,

escapement ratchet wheels by actuation of key 53 at the right hand side of the keyboard, the typist may first depress key I II at the left hand side of the keyboard and hold key I II depressed until key 53 is depressed and allowed to return. By so doing the carriage will be back spaced a fraction only of one letter space and held in this partially back spaced position during a cycle of operation of key 53. This fractional back spacing and holding or locking of the carriage will relieve the pressure of the normally engaged escapement dog with the engaged tooth of the active escapement wheel and facilitate positioning of a tooth of the other wheel in position for engagement by said escapement dog. It will also prevent jumping of the. carriage to the left during a change of escapement wheels.

What we claim is:

1. In a typewriting machine of the kind having a platen and a carriage for said platen escapement-controlled for letter spacing the platen, the combination of escapement dogs, an escapement dog carrier vibrative in a fixed field, a plurality of escapement wheels geared to the carriage and each having a different number of differently spaced teeth, a set of type carriers each carrying as many types of different sets as there are escapement wheels, key-controlled means for selectively actuating the type carriers, key-controlled means for conditioning the machine for typing with either set of types and for simultaneously axially shifting the escapement wheels to present and maintain a selected one of said escapement wheels in position for coaction of the escapement dogs therewith, thewheel presented being different for each set of types, and key-controlled means for holding the carriage against letter feed travel during actuation of the second-mentioned key-controlled means;

2 In a typewriting machine of the kind having a platen and a carriage for said platen escapement-controlled for letter spacing the platen, the combination of escapement dogs, an escapement dog carrier vibrative in a fixed field, a plurality of escapement wheels geared to the carriage and each having a different number of differently spaced teeth, a set of type carriers each carrying as many types of different sets as there are escapement wheels, key-controlled means for selectively actuating the type carriers, key-controlled means for conditioning the machine for typing with either set of types and for also simultaneously axially shifting the escapement wheels to present and maintain a given one of said escapement Wheels in position for coaction of the escapement dogs therewith, the wheels presented being different for each set of types, and key-controlled means for fractionally backspacing the carriage and also holding it so back-- spaced during operation of the second mentioned key-controlled means.

3. In a typewriting machine of the kind having a platen and a carriage for said platen escapement-controlled for letter spacing the platen, the combination of escapement dogs, an escapement dog carrier vibrative in a fixed field, a plurality of escapement wheels geared to the carriage and each having a different number of differently spaced teeth, a set of type carriers each carrying as many types of different sets as there are escapement wheels, key-controlled means for selectively actuating the type carriers, and key-controlled means for conditioning the machine for typing with either set of types and simultaneously axially shifting the escapement wheels to present and maintain a given one of said escapement wheels in position for coaction of the escapement dogs therewith, the Wheel presented being difierent for each set of types, and key-operated means operable by depression and holding down of its key to lock the carriage against letter space movement.

4. In a typewriting machine of the kind having a platen carriage, a dog carrier vibrative in a fixed field, and escapement dogs on the dog carrier, the combination of a plurality of axially aligned and spaced escapement wheels geared to the carriage and each having a different number of differently spaced teeth from all others of said Wheels, key controlled means for. axially shifting said wheels as a unit to position one wheel at a time in an operative position for coaction therewith of the dogs on said dog carrier to letter space the carriage upon vibration of the dog carrier, and key-controlled means for fractionally back spacing the operative wheel to relieve the pressure thereof on the normally engaged escapement dog and for holding the carriage thus back spaced during operation of the first-mentioned key controlled means.

5. In a typewriting machine, the combination of a traveling platen carriage, a feed rack on said carriage, a feed shaft journalled on the frame of the machine and held against axial movement, a feed pinion fixed on said shaft and meshing with said rack, a plurality of externally toothed escapement wheels of equal diameter slidably keyed to said shaft to turn With the shaft and slide as a unit along said shaft, each wheel having a different number of teeth than the others and the teeth of each wheel being uniformly spaced, an escapement dog carrier vibrative in a fixed field, escapement dogs on said carrier, and means for sliding the wheels as a unit along said shaft to position either wheel for coaction of the escapement dogs therewith to letter space the carriage, a back spacing ratchet wheel fixed on said shaft, key-operated means coactive with the back-spacing ratchet wheel to back space the carriage one letter space at a time, and keyoperated means operable on part of said lastmentioned means to fractionally back space the carriage to facilitate change of escapement wheels and lock the carriage during change of escapement wheels.

6. In a typewriting machine, a platen carriage escapement comprising a pair of escapement wheels each having a different tooth spacing from the other, an escapement dog carrier vibrative in a fixed field and having escapement dogs for coaction with one or the other of said escapement wheels, an oppositely movable key, means operable by alternate cycles of operation of said key for alternately presenting and holding different ones of said escapement wheels in position for coaction therewith of the escapement dogs, each cycle of operation of said key consisting of a movement of the key in one direction and a movement of said key in the opposite direction, and key-operated means for fractionally back spacing the carriage and holding it back spaced through said means by manual pressure on the key of said key-operated means.

'7. In a typewriting machine having a shift frame alternately shiftable to either of two positions for conditioning the machine for typing with either of two sets of types, the combination of a platen carriage, a platen on the carriage, an escapement dog carrier, escapement dogs on the carrier, means for vibrating the dog carrier at each printing operation of the machine, two

escapement wheels geared to the carriage and alternatively axially shiftable into position for coaction therewith of the escapement dogs, a connection between said shift. frame and said escapement wheels for so axially shifting the wheels when the shift frame is shifted and holding them shifted until the shift frame is again shifted, and manually controlled means'for shifting the shift frame from either of its positions to the other and holding it there until said manually controlled means is again actuated.

WILLIAM A. GABRIELSQN. EDSON G. MOSHIER.

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