US2305231A

US2305231A - Typewriting machine

Info

Publication number: US2305231A
Application number: US414358A
Authority: US
Inventors: Henry A Avery; Joseph P Barkdoll
Original assignee: LC Smith and Corona Typewriters Inc
Current assignee: SCM Corp
Priority date: 1941-10-09
Filing date: 1941-10-09
Publication date: 1942-12-15
Anticipated expiration: 1959-12-15

Description

Dec. 15, 1942.

H. A. AVERY ET AL TYPEWRITINGMACHINE Fil ed 0ct.- 9, 1941 4 Sheets-Sheet l I HVE In on s l/E/WY /l. A VERY JOSEPH I? flak/(001.1.

WFM

ATT IJHHEY Dec. 15, 1942. H. A. AVERY ET AL 2,305,231

TYPEWRITING MACHINE Filed 001.. 9, 1941 4 Sheets-Sheet 2 ATT mm ET Dec. 15, 1942. H. A. AVERY ETA-L 2,305,231

TYPEWRITING MACHINE Filed Oct. 9, 1941 4 Sheets-Sheet 3 IHVENT u 12 5 HENRY A flws/P Y JOSEPH 1? 6/12/00 ATTORNEY Dec. 15, 1942.

H. A. AVERY ETAL 2,305,231

TYPEWRITING MACHINE 4vSheetsSh eet 4 Filed Oct. 9, 1941 BY g; XT'T URN ET Patented Dec.

, Henry A. Avery and Joseph P. Barkdoll, Groton,

N. Y., alsigllorl to 1. 0. Smith a Corona Typewriters, Ine., Syracuse, N.'Y. a corporation of New York Application mm 9, 1941, serial No. 414,358

.20 Claims. (Cl. rev-s) The invention relates to improvements in typewriting machines and, more particularly, to typewriting machines for typing the scores and lyrics of music compositions.

Important purposes of the invention are .to provide a typewritingmachine with minimum variation from machines most commonly employed for ordinary text typing but well adapted for rapid typing of music scores and lyrics; to provide an improved coordinated arrangement of the types, type case changing means, line spacing means and line finding-means of the usual typewriter facilitating rapid typing of such scores with or without accompanying lyrics; and to provide an improved forward and'backward line spacing means of great accuracy particularly adapted for correct typing of music scores.

Other purposes and advantages of the invention will appear from the foilowing'description in detail of the preferred embodiment'of the invention illustrated by way of example in the accompanying drawings.

. To these ends the invention consists in-the features of construction, arrangements of parts, and combinations of devices and elements particularly pointed out in the appended claims and hereinafterdescribed. i

In the drawings:

Figure 1 is a fragmentary top plan view of an otherwise known typewriting machine modified ,.in accordance with the present invention.

Figure 2 is a fragmentary side elevation of the improved machine, with certain parts omitted as hereinafter pointed out and other parts broken away for simplicity and clarity of illustration of the improvements. Y

Figure-3 is a detail section'on the line. 3-3

of Figure 9, showing more particularly features I of the line spacing mechanism with the operating handle or lever in normal idle position.

Figures 4 and 5 are detail views showing cer- Figure 9 is a detail sectional view approximately on the line 9-9 of Figure 3.

Figure 10 is a'detail sectional view on the line il-lli ofFigure 9.

Figure 11 is a detail front elevation of the line finder or indicator and part of the platen with certain adjacent parts removed and'some broken away for clarity of illustration of the line finder.

Figure 12 is a diagrammatic view hereinafter explained.

v Figure 13 is a view showing the type bearing heads and part of the shanks of five typical type bars of the machine.

Figure 14 is a detail sectional view showing the known segment shift stops of the known machine in connection with which the improvements are f illustrated.

of known machines. Only-so much of the known machine as is necessary to a clear understanding of the improvements has been shown and will be described. 1

The machine hasthe usual arcuate system of type bars 20 pivoted in the usual type bar segment 2| and operable by the usual key actions tain parts at the end of two successive forward line spacing operations of minimum extent, as hereinafter more particularly explained.

Figure 6 is a detail sectional view on the line 66 of Figure 9, showing the forwardline spacing regulator adjusted, however, for a wider spacing than that for which said regulator is set in Figure 3.

Figure "l is a detail sectional view on the line 1--| of Figure 3, showing particularly the line space ratchet wheel det'entgmeans. I

Figure 8 is a-detail sectional view 'on the line 8-8 of Figure 9.

(not shown). The segment is 'shiftable downwardly from a normal lower case printing position to upper case printing position by the usual shift key means. Theusual stop member 22, shiftable bodily with the segment, is engageable with an upper case limit stop 23 on-the stationary main framework of the machine and carries the usual lower case stop 24 normally engaged with lower case limit stop 25 on the main framework.

The type action system and case shift means are more fully shown and described in the patent above referred to. I l I The usual roller platen 26 is journaled in the

end plates

21 and 28 of the usual platen carriage, which carriage is supported on the usual ball bearings to travel horizontally transversely of the main frame on the usual carriage bed 29 which is fixedly held to the main frame. The

'usual finger wheels 30 are connected with the 5 through the usual inked ribbon 32 threaded through the usual ribbon vibrator, parts of which are shown at 33 in Figure 1. It will be understood, of course, that the machine is provided with the usual escapement mechanism for feeding the platen carriage, and with the usual ribbon feeding and vibrating means for the inked the other of which prints in the second case position of the segment. 'A' few typical ones of the type bars are shown. The types which print in normal case position include a full set of alphabet, punctuation and numeral types while the types which print in the other case position are music types for printing the staff, notes and various music signs required to type a music score. The types of the two sets are designated respectively' as 31 and 38 on the drawings.

The set of types 31 are set on the type blocks in known manner for lower case types to type with their bases along the usual writing line of the known machine, said line being indicated by the upper edge portions of the usual line indicating wings 39- of the line indicator 40. At least one of the. wings 39 is preferably graduated as usual at 4| to indicate a plurality of letter space positions of the platen carriage. According to the present invention, the line indicator or finder (which is fixedly held to stationary parts on the main frame of the machine by the usual pair of screws 42) is provided with specially located additional

line indicating means

43 and 44 correlated with the types of the machine as hereinafter explained.

The pointer portions 43 of the indicator indicate the writing line for the set oftypes 38, which line is coincident with that struck by the third or middle line of the staff-printing type of the machine, or the middle line of a staff typed by repeated operations of the staff-printing type. This writing line, as will be observed from the diagrammatic view (Figure 12) showing upper and lower case impressions made by the types of the five type bars shown in Figure 13, passes horizontally centrally through the note head impressions and such impressions as a clef sign, for example. The five horizontal line printing parts of the staff-printing type face shown on the type bar head at the left in Figure 13 are made long enough for slight lateral overlapping or merging of successive impressions made by this type. The size of the note heads, as usual, should not exceed the spacing between the staff lines.

Figure 12 shows successive upper and lower case impressions made by the five type bars shown in Figure 13, the staff lines being pro- Jected across the view by dash lines. It will be noted that the writing line of the lower case or "correspondence" characters is one and one-half staff line spaces or three degrees of the staff below the writing line of the music characters or the middle or third line of the staff. Consequently, it will be noted that the two sets of type characters are set on the bar heads so that the writing line spacing of thetypes on the bar heads for the two sets is greater by three degrees of the staff than the extent of case shift movement.

It will also be noted that the lower case or "correspondence" characters have a maximum height not exceeding two degrees of the staff said height being preferably approximately equal to the spacing of the stafl lines. The lowercase types preferably are a font of lower case or small capitals with punctuation types and numeral types of corresponding size. Lower case Elite Gothic types are shown. The machine may be operated in lower case in the usual manner to type lyrics or ordinary correspondence.. The staff typed by the machine is a widely used size in printed music. 1

Specialline spacing mechanism is provided for line spacing the platen forwardly and backwardly. This mechanism is coordinated with the types and staff size to facilitate writing of music scores and also use of the machine to type correspondencc. It is also designed to insure accurate spacing within the necessary narrow limits, and retention of the platen in accurately spaced position. The spacing apart of the staff lines typed by the machine shown is .0812 inch approximately and is in any case relatively small for the most commonly used sizes of staffs in printed music. It is necessary also to be able to line space one degree of the staff or one-half of the short spacing between staff lines, as is well known.

In the line spacing mechanism shown, the line space ratchet wheel (which is held toplaten 25 in the known manner to rotate with the platen about the platen axis) has its teeth so'spaced that a single tooth space movement of the wheel 45 will turn the platen 28 an extent equal to the space between two adjacent lines of the staff, i. e., two degrees of the staff. The ratchet wheel shown has 49 teeth, and in orderto rotate the platen to line space the paper one degree of the staff it is necessary to be able to rotate the ratchet one-half of a tooth space and hold it so rotated for typing. The use of a relatively coarse toothed ratchet such as shown is highly advantageous in obtaining accurate spacing and in preventing accidental skipping of ratchet teeth as well as accidental overrunning. Inaccurate linesspacing is a known fault of mechanisms employing fine toothed ,ratchets.

A stationary bearing bushing 48 coaxial with the platen has its outer end fixed in carriage end plate 21 and extends inwardly through the ratchet wheel which turns about this bushing. An upstanding pawl-carrying arm 41 is journaled at its lower end on bushing 46 to rock fore and aft of the machine, the lower end of the arm or pawl carrier being confined between the ratchet wheel and a collar 46 formed on the exterior of the bushing. A pivot stud 49, fixed to and extending through the upper end of the pawl carrier 41 longitudinally of and parallel to the platen axis, has Journaled thereon at the right hand face of the pawl carrier the adjacent ends of the two

line space pawls

49 and 59 of identical construction.

The pawl 49 is for forward line spacing and pawl 59 is for rearward or backward line spacing. The axis of stud 49 is above the ratchet wheel and in a plane radial to the wheel axis. Pawls 49 and 50 normally extend respectively rearwardly and downwardly and forwardly and downwardly toward the toothed periphery of the wheel which is thick enoughto be overhung by, and engaged by, both pawls. Each pawl is formed at its free end and lower edge with a notched'nose or twin/noses 5|, The twin noses 5| of each pawl are shaped to closely straddle and fit thetop portion of a tooth of ratchet, or to enter simultaneously and closely fit a tooth space of the ratchet. I

asoaasi' hangs end plate 21 and is formed with an up- Thefree ends ofthe pawls 49 and III are constantly urged toward each other and toward the ratchet wheel by a single tension spring 52 connected'to studs 53 fixed to'the pawls. The pawl carrier 41, and the line'space lever hereinafter described, are held in intermediate normal idle position by a pair of rigid upstanding and oppositely bowed retum or centering arms 54 which position.

4' of bushing 45 and is also afilxed to a stud 5| fixedly held to carriage end plate 21. Plate 51 has a cam hump I! (Figure 6) normally engaged by studs 53 on the line space pawls 49 and "to hold both pawls disengaged from the ratchet 45.

Bracket 51 is formed forward or the free endof pawl" with a laterally extending stop lug vI for pawl 50, and is formed rearward of pawl 49 with a laterally extending stop-lug 5| for pawl 4!. Lug I is inclined to the wheel periphery and so spaced from the normal position 'of pawl '50 as to arrest said pawl when it has rotated the ratchet one-half of a tooth space and to jam said pawl tightly to the ratchet after said rotation. Lug 6| is inclined to the wheel periphery and so spaced from the normal position of pawl 49 as to arrest said pawl when the pawl has rotated the ratchet one-and one-half tooth spaces and thereupon jam said pawl tightly to the ratchet'to prevent overthrow ofthe ratchet and pawl.

Pivoted to bracket 51 to the rear of lug ii on a horizontal pivot 52 is a three-arm forward line-space changing or regulating lever -53 hav- When leverv '53 is and-down extending slot "II in its inner end. Stud 4. is engaged in this slot,-so that when lever 58 is rocked it will rock the pawl carrier 41.

Ratchet detent means are provided for yieldingly detaining the ratchet wheel against rotation in either direction at any half-tooth space This means includes an arm 12 having at its rear end a yoke bearing on a horizontal pivot stud II fixed to and extending inward from carriage end plate 21. Extending inward below the ratchet wheel from the forward end of this arm 12 and fixed thereto is a pivot stud 14 on which is pivoted a small yoke or rocker 15, on which are joumaled on horizontal axes above and respectively fore and aft 'of the axis of yoke I two small detent rollers I5 and I'I.- These rollers are so spaced apart that when either thereof is engaged in a tooth space of ratchet 45, the other is seated against the top. or apexof a tooth of said ratchet. Arm I2 is constantly urged upward by a strong tension spring 18, stronger than spring 52 and connected to the arm 12 and a part of the paper table 35, to press the detent rolls 18 and II upward against the toothed periphery of ratchet 45.:

Stud 5! also serves as a stop to limit rocking of the centering arms 54 under pull of spring 56,

but there is a constant clearance between arms 54 and the bushing 46-46 which is straddled by the arms.

A suitable friction washer 80 is-interposed between one face of the regulator lever. 6501' the line space mechanism and the adjacent face of bracket 51 to hold lever 53 in each of its eflec-' tive positions.

During operations of the line space mechanism the stud 53 on the idle one of 'theline space pawls 49-50 rides slightly along the arcuate top of cm hump 59 on bracket '51. The arcuate top of this hump 59 is concentric with the axes of the platen,-ratchet wheel and'pa'wi carrier.

lever is interposed between pawl 49 and lug 6| to arrest and jam-lock pawl 49 when said pawl has rotated the ratchet one-half-of one tooth space.

To actuate the pawls selectively'for forward,

or backward line spacing as desired, a line space lever 58 is joumaled. on a headed bearing sleeve 69 (Figure 9) held to stud 58. Said lever 68 is formed with a rearwardly extending finger piece or handle depressible for forward line spacing, and is formed with a forwardly extending finger piece or handle H depressible for backward line spacing. In Figures 4 and 5 are shown pawl 49 with regulator 63 set as in Figure 3. As shown in Figure 3, it will .be observed that the notched noses of both pawls are identically related to the adjacent ratchet teeth so that if either finger piece is depressed, the notched nose the end of two successive operating .strokes of v of the efiective pawl will enter a tooth space. T

to alternately fit into a tooth space and fit over.

the top of the next following tooth.

Above its pivotal axis, line space lever is formed withan inward extension 58* which over- With the parts positioned as in Figure 3, de-

pression of finger piece 10 will result in rearward "rocking of pawl carrier 41, stud 53 of pawl '49 will ride down the rear edge of hump 59, nose 5| of ppawl 49 will in its entirety enter the ad- .iacent tooth space of the wheel, and the pawl will thereafter rotate the ratchet wheel. A similar action of pawl 59 will occur if finger piece II is depressed. with the parts in the position shown in Figure 3. If"the ratchet were rotated one-half of a tooth spacefrom the position shown in Figure3, the nose of the active pawl, upon actuation of the line space lever, would engage 'over .the top of the adjacent ratchet tooth to drive the ratchet wheel.

The two sides of each tooth of the ratchet wheel are of equal length and makeequal angles a staff-printing type with. relation to the setting of the note printing types has several advan: tages which will be apparent to those skilled in music notation. The said correlation also-avoids 's'hadow printingWn a machine with convenof certain music types as compared with ordinary text printingtypes employed in conventional ner.

typewriting machines. By shadow printing" is meant at least partial impression by types of one case .when the machine is set for printing in the other case.

The described height or the textprinting characters relativelyto the stafl line spacing is highly advantageous, and the height and relative arrangement of the text printing types with reof the stall printable by the staibprin'ting ty e, and the height of the alphabet and numeral types not exceeding and approximately corresponding to two degrees of the stai! printed by the stafl-printing type.

3. In a typewriting machine as claimed in Y claim 2, means forrotating the platen for line spect tothe staff lines on the stall-printing type facilitates writing of cues, proper placing of time The correlation of the several indications of the line finding device with the writing lines of the two series of types and with the staff printable by the stafl-printingtype is also highly advantageous. Such indications not only facilitate finding the writing lines of the two sets of types within. the limits of the stair, but are also useful spacing paper forwardly and backwardly at will in increments shifting the paper an extent equal to one degree of the staff printable by the staff-' printing type and settable to rotate the platen to line space paper forwardly an extent equal to three degrees of said staff.

4. In a typewriting machine as claimed in claim 1, line indicating means associated with the platen to indicate the writing lines of the to flndstafl and degree lines above and below a stall typed by the machine, and in locating lines The line spacing means is peculiarly adapted for accurate spacing within extremely narrow limits required in music typing without overthrow or back lash, and is correlated for eflicient use with the staff typed by the machine. The half-tooth forward or backward line spacings each feed the paper one degree of the stafl, and the optional one and one-half tooth forward spacing aifords complete clearance between succesive lines of text typing. Extremely accurate extent of rotation of the platen and accurate holding of the platen in accurately spaced position are highly essential to typing intelligible music scores, and due to the small linear extent of a staff degree such accurate line spacing and platen detention must be obtainable with extremely fine limits of line space actuation of the platenratchet. The line space mechanism disclosed permits a minimum line space driving of the ratchet corresponding to one-half of a tooth-' space turn of the ratchet. The ratchet can be zumed in either direction by the pawl mechanism and also by the finger wheels of the platen and will be detained at half-tooth intervals by the detent means shown.

We claim:

1. In a case changing typewriting machine having a platen and a set -of types coactive with the platen 'to type correspondence in one case printing setting of the machine, a set of music score typing types coactive with the platen to type in the other case printing setting of the matwo sets of types. 7 i

5. In a typewriting machine as claimed in claim 2, line indicating means associated with the platen including means'to indicate thewriting line of i the first set of types, means to indicate the line upon which the staff-printing type will impress the third or middle line of the staif, and means to indicate the line upon which the stair-printing type will impress the second line of the staff, the line of impression of the middle line of the staff-printing type being the writing lin of the music types.

6. In a single shift'case changing typewriting machine-having a rotatable platen roll and type bars carrying a set of alphabet, numeral and punctuation types coactive with the platen roll toprint text'along a writing line in the normal lower case printing setting of the machine, the platen and type bars being relatively shiftable for case-change, the'combination of music types, including a staff-printing type, carried by the type bars for coaction with the platen to type in the upper case printing setting of the machine along a writing line coincident with the line of impression of the middle or third line of the staff-printing type. the locations of said music types on the type bars with respect to the first set of types being such with respect to the extent of case shift that the writing line of the music types is three degrees of the staff above the writing line of the first-mentioned set of types,

by-the staff-printing type.

chine, the types and platen being relatively shiftable for case changing, and the types of one set being coactive with the platen to type on a different writing line from that on which the other set is adapted to type.

2. In a case changing typewriting machine with single case shift having a platen and a set of alphabet, numeral and punctuation types coactive with the platen to print text in one case printing setting of the machine, said alphabet types being capital types, a set of music type including a staff-printing type coactive with the platen to type in the other case printing setting of the machine, the said music types being mounted relatively to the first-mentioned set of types to coact with the platen along a writing line diil'erent from that of said first-mentioned set of types by a spacing equal to three degrees 7. A typewriting machine as claimed in claim 6, wherein the alphabet and numeral types are characterized in that the maximumheightthereof is approximately equal to two degrees of the staff printable by the staff-printing typ and the line spacing means is characterized in'that means is provided for setting it for forward line spacing in increments equal to three degrees of the stafl. printable by the stafi-printing type.

8. A singlecase shift typewriting machine having a rotary platen and type bars each carrying two types and the platen and type bars being relatively shii'table a fixed extent to permit printing impressions of different types on a bar, the types on the bars eflective in one relatively shiftable position of the platen and bars being .music' types and the music type on one of said types being located on the bar so that the "writing line of all of the music types is coincident I with the'third line of the stat! printable by the staiI-printing type, line spacing means to rotate= the platen to line space paper in increments of one degree of the stall! printable by the stanprinting type, andmeans to indicate said writing line. p

9.-A single case shift typewriting machine as claimed in claim 8, wherein type bars of the machine carry text printing types effective in I the other relatively shifted position of the platen and type bars to print.

10. A typewriting machine for typing music,

including a rotary platen, a staff-printing type. coactive with the platen for printing simultaneously a portion of each of the five lines of .a music stafl, said portions being long enough tomerge end to end upon successive impressions of said type, a line space ratchet wheel held to the platen to rotate therewith coaxially with the platen and having its teeth spaced to rotate the platen to line space paper per tooth space rotation oisaid wheel two degrees of the stat! printable by said stair-printing type, line spacing means coactive with said wheel to turn it selectively forwardly or backwardly at each operation in hall-tooth .increments, and yieldable detent means, .coactive with said wheel to detain it at any halt tooth rotated position.

11. A typewritingmachine as claimed in claim 10, wherein said line spacing means includes a regulating means whereby the line spacing means may be set to rotate the platen in one direction at a single operation through a plurality of half tooth spaces.

12. A typewriting machine as claimed in claim "10, wherein the line spacing means coactive with said ratchet wheel includes a pawl carrier oppositely rockable about the axis of said wheel, yieldable means for normally centering said carrier in idle position, a pair of pawls pivoted to the carrier and constantly spring-urged toward the 5 able detent means coactive with the wheelto hold the wheel in any halt-tooth space rotated position.

I 15.11; aftypewriting machine '61, the class "dc scribed, a rotatablejplaten, a line space ratchet wheel connected with the platen to rotate the latter for line spacin'ga work sheet, a pair of line space pawls selectively operable upon aid wheel to rotate the latter in diflerentdirections,

, means for actuating the pawls to render the selected one effective to drive the wheel, each pawl having a notched nose closely nttable either into a tooth space of the wheel or over the top .able detentmeans to hold the wheel at any hall tooth space. rotated position of the wheel, a pawl pivoted on the pawl carrier and spring-urged to the wheel, said pawl having a notched nose shaped to closely flt in its entirety in a tooth space of the wheel and to alternatively snugly receive in its notch a tooth of said wheel, means to normally hold said pawl retracted from the wheel, means to normally return the pawl car- -rier to an idle position, means to rock the platen, one pawl engageable with the wheel to turn the latter in onedirec'tion and the other pawl engageable with the wheel to turn the wheel in the opposite direction upon'rocking of the carrier in different directions from its normal idle position, means for normally holding both pawls disengaged from the wheel and for holding each pawl out of engagement with the wheel during working and return strokes of the other .pawl, and means for limiting the working strokes of the pawls, each pawl having a notched nose shaped to closely fit in a tooth space or the ratchet wheel and to closely fit over a tooth of the wheel alternately upon successive half-tooth rotations of the wheel by the pawl.

13. A typewriting machine as claimed in claim pawl carrier from idle position to actuate the pawl to drive the ratchet wheel, and means to limit rotation of the wheel by said pawl to onehalf of a tooth space of the wheel.

'17. In a typewriting machine, a rotary platen,

a line space ratchet wheel coaxial with the platen and'rotative therewith, a pawl carrier rockable about the axis of the wheel and platen, yieldable detent means 'to-hold the wheel at any half tooth space rotated position of the wheel. a pawl pivoted on the pawl carrier and spring-urged to the wheel, said pawl having a notched nose shaped to closely fit in its entirety in a tooth space of the wheel and to alternatively snugly receive in its notch a tooth of said wheel, means to normally hold said pawl retracted from the wheel. means to normally return the pawl carrier to an idle position, means to rock the pawl carrier irom idle position to actuate the pawl to drive the ratchet wheel, and means selectively 10, wherein the detent means for the ratchet wheel includes a rocker, a pivoted arm supporting said rocker to tilt about an axis extending transversely oi the wheel, a pair of detents on said .rocker spaced for seating of one into a tooth space of the wheel while the other is seated on the apex of a tooth of the wheel, and spring means urging said arm to press said detents to the toothed periphery of the ratchet wheel.

14. In a typewriting machine of the class described, a rotatable platen, a line space ratchet wheel connected with the platen to'rotate the latter, a pair of line space pawls operative on said wheel selectively to rotate it in opposite directions, means for actuating either pawl to rotate the wheel, each pawl having a notched nose shaped to closely fit either into a tooth space settable to limit rotation of the wheel by the pawl to either one-half ofa tooth space of the wheel or a multiple of said one-half of a tooth space.

18. In a typing machine of the class described, arotary platen, a ratchet wheel coaxial with the platen and rotative in unison therewith, a pawl carrying arm oscillative about the platen axis, yieldable means to hold the pawl carryin arm in an intermediate idle position, forward and backward line spacing pawls pivoted to the pawlcarrying arm on a common axis, a fixed cam engageable by the pawls to normally hold both pawls out of engagement with the ratchet wheel and engageable by each pawl to hold it out of engagement with the ratchet wheel during working and return strokes of the other pawl,

, a line space lever oppositely tiltableabout a fixed v fulcrum and engaged with the pawl carrying arm of the wheel or over a wheel tooth, and yieldto rock the latter in opposite directions from idle position upon tilting of said lever in opposite 6 Y 1 2,305,931 directions from a normal idle position in which it is held: by said arm, eachpawl having a notched nose shaped to closely fit alternatively entirely into a tooth space of the ratchet 'wheel or ovena tooth of said wheel, detent means,- coactive with said wheel to hold the wheel yieldingly in any one-halt tooth space rotated position thereof, and control m'eans'for limiting rotatlon oi the wheel by either pawl to one-half of atooth space. p

19. 'In a typewriting machlnehas claimed in claim 18, control means for limiting rotation of the wheel by the pawls, including aregulating means settable to permit rotation of the wheel by one pawl a multiple ota one-halt tooth space of the wheel.

20. ms typewrit ing mm; as claimed in claim 18, detent means for the ratchet wheel including a rocker tiltableabout an axis extendingtransversely of the ratchet wheel, arpair of detent rollers journaled on the rocker to seat one in a tooth spaoeof the wheel while the other is seated on the apex oi a tooth of the wheel, and a support for said rocker spring-urged to press said rollers to the periphery of the ratchet wheel. a v

HENRY A. AVERY. I JOSEPH P. BARKDOLL.