US1718043A - Fractional-line-spacing mechanism for typewriters - Google Patents

Description

June 18, 1929. HARDlNGHAM 1.718.043

FRACTIONAL LINE SPACING MECHANISM FOR TYPEWRITERS Filed March 23, 1926 Patented June 18, 1929.

GEORGE GAT'ION MELHUISH HARDINGHAM, OF WESTMINSTER, ENGLAND.

FRACTIONAL-LINE-SPACING MECHANISM FOR TYPEWRITERS.

Application filed March 23, 1926, Serial No. 96,855, and in Great Britain Apri1'2, 1925.

This invention relates to line-space feed mechanism applicable to typewriters. According to the usual method of constructing such mechanism, thepaper-carrying cylinder is rotated bymeans of a ratchetwheel operated by a pawl, which in turn is actuated by the movement of the carriagelever. The motion of the pawl may be regulated to take one, two or more, teeth of the ratchet-wheel; but the extent to. which the cylinder is rotated and the paper is fed is restricted to a difference corresponding.

with that of one tooth. It has, however, been proposed to substitute herefor feed mechanism designed to rotate the papercarrying cylinder by means of appliances which frictionallyt'engage therewith, in conjunction with means for minutely adjusting the degree of angular movement imparted to the cylinder and consequently the extent of the feed.

lily improved line-spacing mechanism is of the latter type, and comprises a primary lever, fixed on the carriage-lever spindle, and a secondary lever, freely mounted on the same spindle and carrying alpivoted pawlarm; the forward movement of the primary lever being communicated to the secondary lever through the pivot of the pawl-arm the return movement of the lever and pawlarmbeing limited in extent by the angular position occupied by a cam adjusted to the particular line-spacing required.

Such facilities for adjustment are particularly useful when retyping amended documents. Assuming matter occupying three lines to have been added to or deleted from 27 lines, the feed may be adjusted in such a manner as to make 30 lines or 24 lines, as the case may be, occupythe same space on the sheet as previouslyoccupicd by the 2'7 lines; all the lines on the retyped sheet being equally spaced apart. Means for effecting a minute adjustment of the linespace feed enable, moreover, the typewriting tobe arrangedon lines already ruled.

Line-spacing mechanism constructed according to my improved method and applied, by way of example, to a No. 7 Remington typewriter, is illustrated in the accompanying drawings, whereof Fig. l is a side elevation Fig. 2 is a plan view,

-Fig. 3 is a detail view of one element,

3 and S are front and. eleva ticns efa modification,

Fig. 4 is an elevation of one lever,

Fig. 5 is an elevation of the feed arm,

Figs. 6 and 6 show a front elevation and a plan of a modified form of cam adjustment.

On the spindle a of the carriage-lever a e are mounted two levers b, 0,1s1de by side;

outer or free end of the pawl-arm cl carries a pivoted friction-pad d which engages the periphery of a drum 6 fast on the spindle of the cylinder f. This drum may be composed of the material with which typewriter cylinders are commonly covered. Or what is known as red fibre may be employed, in which case its periphery is formed with circumferential ribs of V-section; the c0ntacting surface of the pad (l being grooved to correspond, to ensure frictional grip when the grooved pad is firmly held down upon the ribbed drum. Mounted to bear against the upper extremity of the secondary lever 0 is a cam g, capable of being rotated by hand; the angular position of this cam restricting, in variable degree, the

backward movement of the pawl-arm, there- I by determining theextent of its subsequent forward movement, and consequently the extent to which the cylinder 7 is rotated at each operation of the carriage-lever w. Upon the spindle of the cam g and rotating therewith is a graduated disc 71/, and fixed upon the bearing of the cam-spindle is an index-finger 71 The secondary lever 0 is formed with a projecting arm 0 which, when operated, abuts against the portion f of the cylinder f, for the purpose of limiting the forward movement of that lever and at the same tnne, 1ts leg 0 arr ves 1n contact with and depresses the bar j whereby the release of the carriage is effected.

In order to effect the return movement of the secondary lever, it is forined with slot 0 wherein a pin 5 carried bytl'ie'priinary works. (31:, "with the ob ect, the

being nevertheless retained. For instance,

back edge of the lever b may be formed with a snug I) which projects laterally into the path of the lever b as illustrated in the detachedviews, Figs. S and 3". -When the leading end of the slot 0 is closed, such. closed end is arranged beyond the reach of the pin I) in order to provide against the pin operating to advance the secondary lever; the forward movement of this lever being effected exclusively through the toothed sector and spurgear 6 al For preventing or checking the movement of the cylinder after its partial rotation has been effected and the feed-pad draised out of engagement therewith, the bar may if desired be furnished with a friction-pad j, which, upon the said bar rising, bears against the under side of the cylinder-spindle, or of a friction-drum fast thereon.

From the foregoing description, it will be realized that the initial action of the primary lever b is not to advance the pawl-arm d, but to rotate it about its pivot until the friction-pad (Z ,'C2L1L'l8Cl by it, has been forced down into frictional engagement with the periphery of the cylinder-drum e, in which condition it is maintained by reason of the power employed in the feeding operation being transmitted from the primary to the secondary lever through the toothed sector and spur-gear. Upon the friction-pad having thus become engaged with the cylinderdrum, the continued forward movement of the primary lever, now working in unison with the secondary lever and its pawl-arm, rotates the cylinder and feeds the paper. Upon the completion of this movement, the primary lever is released, and, under the influence of a spring applied thereto, makesits return stroke. The first effect of this movement is, however, to vibrate the pawlarm about its pivot in the reverse direction, and thereby to lift the friction-pad out of engagement with the cylinder-drum; the backward movement of the pawl-arm being ultimately arrested upon the upper extremity of the secondary lever coming into contact with the cam g. Concurrently with the release of the primary lever, the springactua'ted bar j rises, thereby brin ing its friction-pad, if so provided, into operation to hold the cylinder-spindle against accidental rotation in either direction until the paper-feeding operation is repeated.

Although, for the purpose of explaining the construction and operation of my improved feed mechanism, it has been described as applied to a Remington typewriter, it will be understood that, in apply ing it to other machines furnished with a ratchet and pawl-feed, modifications in certain of the details may become necessary, the essential characteristics of the apparatus as illustrated in Figs. 6 and 6, a face-cam 9 may be substituted for the circumferential cam, and the index-dial h arranged to read from the front, instead of from the end, of the machine. Or, as illustrated in Fig. 1, instead of grooving the periphery of the drum 6 and forming the face of the feed-pad (Z in a corresponding manner, freedom from slip? may be obtained by forming the drum 0 of hard rubber or similar l'natcrial, and the feed-pad (Z of steel or the like, the working face of the latter being serrated.

I claim 1. In a typewriter, fractional line-spacing mechanism comprising a primary lever, a secondary lever, a pawl-arm pivotally mounted upon the latter, and a cam-surfaced body capable of rotative adjustment and arranged behind the secondary lever to serve as a stop to their backward movement; the forward movement of the primary lever being transmitted to the secondary lever through a turning effort about the pivot of the pawl-arm.

2. In line-spacing mechanism for typewriters, the combination of a primary lever, a co-axially mounted secondary lever, a pawl-arm pivotally mounted upon the secondary lever, and means for transmitting the forward movement of the primary lever to the secondary lever through a turning effort about the pivot of the pawl-arm.

3. In a typewriter having a carriage-lever and a feed drum, fractional line-spacing mechanism comprising a primary lever adapted for operation by the carriage lever, a secondary lever mounted co-axially with the primary lever, a pawl-arm pivotally mounted upon the outer end of the'secondary lever, said pawl-arm carrying a feed-pad adapted to engage the peripheral surface of the feed drum, and means carried by the outer end of the primary lever and engaging eccentrically with the hub of the pawl-arm for imparting rotative movement thereto, wit-h the effect that the forward movement of the primary lever operates, first, to turn the pawl-arm about its pivot until its feed: pad engages with and grips the surface of the feed drum, and subsequently, to advance the secondary lever and pawl-arm to rotate the said drum. 7

4-. The structure as set forth in claim 3 wherein an adjustable cam is mounted immediately behind the secondary lever to serve as a variable stop to the backward movement of the said lever; said cam being furnished with an index plate which rotates with the cam in relation to a fixed pointer.

5. The structure as set forth in claim 3 wherein said feed drum has a surface formed with circumferential V-grooves, and the said feed-pad has its working face formed with corresponding ridges adapted to engage in the said grooves for the purpose of augary lever, a pin projecting laterally from menting the frictional grip of the feed-pad the primary lever and adapted to engage 10 upon the feed drum. with the secondary lever for effecting the 6. Fractional line-spacing mechanism comreturn movement of the latter in company 5 prising aprimary lever fixed on the carriage- 'With the primary lever after the latter has lever spindle, a secondary lever freely rotated the pawl-arm about its pivot to lift mounted on the same spindle and a pawl-arm the feed-pad clear of the cylinder-feed-drum. pivoted at the outer extremity of the second- Gr. G. M. HARDINGHAM.

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