US2650687A - Stop positioning mechanism for typewriters - Google Patents

Description

sept-1, 1953 4 Sheets-Sheet l Filed May 26, 1948 muil m wim WK f,/u. f, wf.- -M

Sept. 1, 1953 w. F. HELMOND 2,650,687

sToP POSITIONING MECHANISM FOR TYPEWRITERS Filed may 26, 194s 4-sheetssneet 2 Sept- 1, 1953 v w. F. HELMOND 2,650,687

STOP POSITIONING MECHANISM FOR TYPEWRITERS Filed May 26, 1948 4 Sheets-Sheet 3 1N 0R. M F MMD Afm/amy Sept. l, 1953 w. F. HELMOND STOP PosrTIoNING MECHANISM vPoR TYPEWRITERS Filed May 26, 149.48

?NVEN TUR.

Patented Sept. 1, 1953 STOP POSITIONING MECHANISM FOR TYPEWRITERS William F. Helmond, Clinton, Conn., assignor to Underwood Corporation, New York, N. Y., a corporation of Delaware Application May 26, 1948, Serial No. 29,253

19 Claims. 1

This invention relates to typewriting machines and more particularly to devices in such machines for conveniently positioning carriage locating stops in desired positions by control means remote to the stops and conveniently accessible to the operator.

Devices of this general nature are old in the art and many are disclosed in expired patents, and are usually in the form of margin regulating devices.

One of the objects of the invention is to provide a remote-control stop positioning device which is durable, and reliable in operation.

It is another object of the invention to provide such a stop positioning device without addition of any appreciable weight to the typewriter carriage, wherefore the carriage is capable of letter-feeding at maximum speed, efciently, and with a minimum of strain, noise and vibration.

It is a further object of the invention to provide a remote-control stop positioning device which can be manufactured at very low cost, and nevertheless is supreme in efliciency and performance.

It is a still further object of the invention to provide a simply constructed, light-weight, reliably operating device to selectively release one or another of two margin stops for adjustment to diiferent margin-defining positions, the

typewriter carriage, including also certain portions of the stationary part of a typewriter, taken substantially along line l-l of Figure 4,

Figure 2 is a fragmentary plan view of a righthand portion of the typewriter carriage, including a selective margin stop releasing control,

Figure 3 is a fragmentary front elevation of a line-end margin stop in association with a line-end signalling device,

Figure 4 is a skeletonized plan view of the typewriter carriage and portions of the machine proper, the novel remote control stop positioning device being included in the showing,

Figure 5 is a left-hand sectional side elevation of a line-end margin stop including some immediately associated parts, in normal condition, and taken along line 5 5 of Figure 4, Y

Figure 6 is a view similar to Figure 5, and shows the same margin stop released for repositioning,

Figure 7 is a sectional view taken along line I-T of Figure 4, and depicts the left-hand margin stop held in a margin defining position,

Figure 8 shows the stop of Figure 7 released for repositioning,

Figure 9 is a right-hand end view of a rear portion of the typewriter carriage, showing specifically a control whereby the margin stops are releasable selectively for individual repositioning,

Figure 10 is a sectional front view of most parts illustrated in Figure 9, the section being taken substantially along line lll-IU of Figure 9, and

Figure 11 is a sectional plan view of a carriage return position defining margin stop held in a position on a supporting rack.

Referring now more specifically to Figure l, a carriage, generally designated by the referencecharacter I U, includes a grooved rail Il which by means of anti-friction elements l2 is guided in a grooved trackway I3 that is part of the stationary framework of the machine. Said carriage includes spaced ends I rising from the carriage rail Il, and a platen roll l5 is turnably mounted in said carriage ends in a wellknown manner. s

Normally the carriage is under control of a letter-feed escapement comprising a holding dog I 'l and a stepping dog i8, the holding dog. l1 being normally in engagement with an escapement wheel 20. Said escapement wheel 2D is carried on a vertical shaft 2| carrying at its upper end a pinion 22 in engagement with a carriage supported rack 23. Said escapement wheel 20, the shaft 2| and the pinion 22, oonstitute a unit rotatively carried on the frame by means of brackets 24, 25, about the shaft axis. The carriage is urged to move in letterfeed direction, that is, rightwardly as viewed in Figure 4, by spring tension, as usual, by means not shown, and incident to each typing or word spacing operation the escapement Il, i3 is vibrated, permitting a letter-feed movement of the carriage under urge of said spring tension, in the conventional manner.

The rack 23 constitutes part of a pivoted structure including two side arms 30, each having a fulcrum 3| on an upstanding bracket 32 on the carriage rail II. For locating the carriage quickly in any desired position, the rack 23 is adapted to be raised free from the pinion 22 by rocking said pivoted structure upwardly about said pivots 3|. Such rocking is effected at will by operating a carriage release lever 33 fulcrumed at 34 on the carriage and connected by means of a link 35 to said rocking structure. A spring 36 connected to an ear on the link 35 is instrumental to maintain the rack 23 releasably in mesh with the pinion 22.

To the rear of the platen there rises on an upward and rearward incline, between the two carriage ends i4, a usual paper shelf 31. This shelf is supported at each lateral end by a bracket 38, see Figures 1 and 4, each bracket having a rear leaf 40 reaching behind a rear iiange of the ad jacent carriage side plate I4 for a screw 4I to secure it thereto. Each bracket 38 includes also a rest 3'Ia for the paper shelf 31.

Carried by and extending along the extreme rear of the carriage is an inverted U-shaped bar 42 constituting a rack for supporting, at letterspace intervals, key-settable tabulator stops 43. This rack and the key-settable stops thereon are of known design, and whatever tabulator stops 43 may have been set, are adapted to be engaged by tabulator counterstop means 44 under tabulator key control, not shown, said counter-stop means being shown in Figures 1 and 4 to protrude from a housing 49 constituting part of the framework of the machine. The U-shaped rack 42, at the left end of the carriage, is supported by a bracket 45 which is fastened to a ange 46 of the left carriage end by a screw 41, the rack being secured by a screw 48 to said bracket. The right end of the rack is similarly supported on a bracket 50, but this latter bracket, see Figure 4, is formed to secure it to the right carriage end by the same screw 4I which serves to hold the bracket 38.

described is conventional typewriter structure, and, directing attention temporarily more particularly to Figure 4, it will be seen that 0n the carriage there extends in front of the tabulator rack 42 a round bar 52 which along its rear side and its front side aords opposite rows of teeth, or racks 53 and 54, respectively, the individual teeth of the rack 53 having sides which are square to the rod, and the teeth of the rack 54, for reasons to be pointed out later, being of buttress form. Upon said rod 52 there is carried a left margin stop IL, and a right margin stop IR4 such stops comprising block-like bodies 2L and 2R, respectively, having cylindrical extensions 3L and 3R, respectively, reaching toward each other. Said margin stops iR and IL are provided with smooth bores 63 extending concentrically of said cylindrical extensions, fully through the stops, and the rod 52 supports both said stops by extending through the bores thereof. The rod 52 is supported pivotally on the carriage, at the right end of the carriage in the bracket 50, and atl the left end of the carriage 1n a forward extension of bracket 45. Specifically, the left end of the rod 52 has a reduced end 55 reaching through and pivoted in the bracket extension 4:, and carrying a retainer collar 56 outside of said bracket extension, whereby the rod 52 is longitudinally restricted to partake in all carriage movements.

The margin stops IL and IR have each a vertical rear face 66 which in conjunction with the broad front face of the tabulator stop carrying bar 42 constricts the stop against turning about the axis of the rod 52.

At the right-hand end of the carriage there is associated with the rod 52 a control member or manipulative arm BI headed by a round nger piece 62. Normally this manipulative arm is vertically positioned, as seen in full lines in Figures 1, 2, 4, 5, '7 and 9, and thereby normally determines the pivotal position of the rod 52 so that the rows of rack teeth 54 and 53 thereon stand respectively fore-and-aft of the machine as seen in Figures 1, 4, 5 and 7. With the rod 52 so positioned, both the margin stops are coupled or locked to the rod in specific margin-defming positions, in a manner presently to be described.

On the right margin stop IR, see Figure 5, a dog 4R is pivotally supported for movement into and out of engagement with the rack 53, by a. pin 5R, located to the rear and above the rod 52, and may be in engagement in any of the notches in the rack 53. A slot 58 in the stop accommodates the dog for free pivotal movement. A compression spring 6R contained in a socket hole IR pushes against the upper end of the dog 4R so as to bias its lower end into locked engagement with the rack 53. Thus the right margin stop IR is normally locked in a specic margin-defining position along the rod 52.

The left margin stop IL, see Figures 4, 7 and 1l, has a dog 4L which normally s in engagement in any of the notches in the row of buttress teeth 54. This dog 4L is accommodated in a slot of its stop like the dog 4R, and is pivoted in its stop by a pin 5L located in front of and above the rod 52. A spring 6L accommodated in a hole, similarly to the spring 6R, presses the dog 4L into stop-locating engagement with the row of buttress teeth 54.

For reasons which will be made clear later, the margin stop IL has an additional dog 8L which normally is in engagement with the rack 53. This dog 8L has a pivot pin 9L which is located below the rod 52 and a spring IOL presses its upper end resiliently into toothed engagement with the rack 53.

In establishing the writing-line margins the margin stops IL and IR cooperate with a counterstop 61 which protrudes upwardly through a perforation 68 in the housing 49 of the machine framework located below the margin stops. Said counterstop 61 is in the form of an upright element normally adapted to pivot about a point 69 to the limit permitted by the perforation 68, against the tension of a fairly strong spring 'I0 urging said element upwardly and rightwardly. The left margin stop IL cooperates with the counterstop 61 by means of a face 'I I, see Figures 4 and 11.

Referring to Figure 1l, it will be seen that the dog 4L ts the notches in the rack 54 while, on the other hand, the dog 8L is narrower than the notches of rack 53 and has a loose t between the teeth. Incidental to the arrest of the carriage during carriage return, the stopping impact is transmitted by the dog 4L, to the buttress tooth of rack 54 which is to the left thereof, but, even in machines designed for small letterfeed, this dog and any of the buttress teeth can easily withstand the strain by reason of their buttress tooth form. The dog 8L may take some of the carriage arresting load, but primarily serves to lock positively the margin stop IL normally against leftward displacement on the carriage, and also to keep the left margin stop reliably interlocked with the rod 52 while the right margin stop is being adjusted, as will yet become evident.

The left side face 'I2 of the margin stop block 2R of stop IR cooperates with the counterstop 8l through the intermediary of an interponent 'I3 carried on the block, and the purpose of which will be brought out later.

The margin stop IL, of course, constitutes a return limiting stop, the return limit being established by the stop face 'II thereon engaging the counterstop 61. The margin stop IR, in the typing of a line, through the interponent I3 carried thereon, at the approach of the line end, see Figure 3, will first operate a line-end signalling device comprising a lever 'I5 pivoted at 16, the lever having a bell-ringing end 'I'I adapted to strike within a bell globe 'I8 after iirst displacing the lever anti-clockwise of Figure 3, and incidental to riding clear thereof to the left. The spring =80 resiliently urges the bell lever 'I5 to the normal position shown in Figure 3, and supplies the bellringing power. About six .letter-feed advances of the carriage leftwardly after the sounding of the bell, the interponent 'I3 on stop IR will cause a leftward displacement of the counterstop 61 against the tension of the counterstop spring l0, and such displacement, through operation of a line-end locking lever 'I5 pivoted at 16, will incapaoitate the typing mechanism in a manner well known in the art. However, the operator may type additional characters upon operation of a margin release control, not shown, which lowers the counterstop 61 below cooperative range of the margin stops. Typing to the left of the position dened by the stop IL is also possible by use of the margin release control. The margin stops IR and IL have each a usual cam face at their bottom, and these faces, by riding over and depressing the counterstop 61, allow the carriage to be brought readily back within the defined marginal positions. In doing this with reference to the stop IL, the toothed engagement with the bar afforded by the dog 8L insures against shift of the stop rightwardly which may be permitted by the dog 4L.

M arg/in stop adjustment The margin stops IL and IR are selectively releasable from the supporting rod 52 by movement of the manipulative arm or control 6I respectively forwardly and rearwardly to abnormal positions. If moved rearwardly to the abnormal position seen in Figure 6, the resultant turning of the rod 52 will cause the dog 46 to be cammed clear of the rack 3, out of the tooth notch, and onto a smooth longitudinal surface directly above such rack. However, this rearward positioning of the manipulative arm 5I and the consequent turning of the rod 52 is not sufcient to free the left margin stop IL from toothed interlock with the rod 52. This will be perceived from Figure 6, wherein the dog 8L for the left margin stop IL is shown in dot-and-dash lines, and, though partially crowded outwardly, is still effective to hold its associated margin stop locked to the rack 53 and thus located on the rod 52.

In the embodiment of the invention shown, the margin stops are resiliently urged toward each other, by a device comprising a spring drum 8| carried by means of a stud 82 on the margin stop IR, having a flexible element or string 83 wound thereupon and extending to and connected to the left margin stop'by means of a stud 84. A clock spring 85 within the drum 8| and having an inner anchorage on said stud, supplies the power for the drum to wind the string 83.

It will thus be seen that when the manipulative control 6I is moved rearwardly, the stop IR will be drawn resiliently leftwardly to encounter the counterstop 61 (if not already located thereagainst), and thereupon adjustment of the stop IR can be effected by merely operating the aforementioned carriage release lever 33 and moving the carriage, the margin stop remaining throughout in abutment with the counterstop, that is stationary with respect to the machine frame. If then the manipulative control 6I is restored to normal position, the margin stop IR will become relocked along the rod in the desired new position by means of the dog 4R entering the proper notch in the rack 53 under tension of the dog spring 6R. In conjunction with effecting the adjustment of the line-end margin stop IR, it is to be noted that the spring power urging this margin stop I R leftwardly is inferior to the power of the spring T0 urging the counterstop rightwardly, whereby the relocation of the margin stop IR is controlled by the counterstop El always while the latter is in its rightward position shown in Figure fl. Moreover, it follows that the new position given the margin stop IR is representative always of theV last possible typing position of the carriage before the typing mechanism is incapacitated through leftward displacement of the counterstop 61, as pointed out before.

When the manipulative control 6I is moved forwardly, from normal upright position to the full line, abnormal position shown in Figure 8, both the dogs 4L and 8L associated with the margin stop IL will be cammed outwardly bythe rod 52 against the tension of their light dog springs to free them from interlock with the racks 53 and 54. Both said clogs are then clear of their associated racks and bear then resiliently against smooth longitudinal surfaces on the rod 52 as shown in Figure 8, wherefore the associated margin stop IL is free for movement along the supporting rod 52, and the flexible bandintermediate the two margin stops will then cause movement of the margin stop IL against the counterstop 61. The desired location of the margin stop is then obtained by merely moving the carriage to the desired return limit position and then restoring the manipulative control 6I to normal position, this causing the dogs to relock the margin stop in the desired position.

It should be noted from Figure 8 that while adjustment is effected of the left margin stop IL, the right margin stop IR remains locked to the rod 52 through the dog IBR which, although partly displaced outwardly by the turning of the rod 52, nevertheless remains controllingly in its engaged tooth notch.

The manipulative control 5I has a device associated therewith which resiliently biases such arm to restore to its normal, upright position. In this connection more specific reference is made to Figures 2, 4, 9 and 10. First referring particularly to Figure l0, it will be seen that the rod 52 outside of its supporting bracket 56 has a reduced en 8E whereupon there is held, as by a set screw 8l, a collar 88. This collar has a broad vertical groove 89 to confine the lower end of the manipulative arm 6I which has a perforation 90 to locate it upon a shouldered stud 9| screwed in the reduced shaft end 86. Said stud has a large head 92, between which and the control arm BI there is provided a compression spring 93 resiliently positoning the control arm normally flatly against the base of the groove 89, but permitting some swinging displacement rightwardly and leftwardly as indicated in Figure 10.

Upon the right side I4 of the carriage frame there is secured, as by screws 94, a bracket 95 affording individual pivotal supports 96 for two arms 91 which by a spring 98 are drawn toward each other to definite positions, giving normally the control arm 6I. and therefore the rod 52, a definite pivotal position. The said arms 91, in their normal positions, have toes 99 bearing against a shelf |09 of the bracket 05. The upper ends of the arms 91 have horizontal ears |0I to provide broad contacting faces for the arm 6|. Following operation of the manipulative arm 6| either forwardly or rearwardly, and upon subsequent release thereof, the control arm 5I will automatically reassume normal, that is, upright position under the action of the spring-inuenced arms 91.

The extremes to which the control arm can be swung forwardly and rearwardly are established by limits afforded in a bracket |02, by respectively the forward end of a slot |03 and a rearward end of a slot |04 in such bracket, see particularly Figures 2 and 9. As seen in the plan view of Figure 2, the slots |03 and |04 are out of line with respect to each other and have a connecting clearance |05 whereat the control arm 6| is normally restricted against direct rearward or direct forward movement. In order to move the control arm 6I rearwardly for effecting an adjustment of the right margin, the operator is rst required to give the arm 6I deliberately a right- Ward thrust to line it up with the slot IM. The lever 6I, of course, is capable of rightward and leftward displacement by reason of its being accommodated in the collar groove 89, and for the reason that the spring 93 is yielding.

To effect an adjustment of the left margin stop the operator is rst required to move the control arm BI deliberately leftwardly into alignment with the slot |03, and then forwardly. Upon release, either after forward or rearward displacement, the control arm will be springrestored and will always be intercepted and held in the connecting clearance |95, as seen in Figure 2` It will be noted that in so assuming normal position there cannot be an overthrow beyond the normal position. 'I'he bracket |02 has a vertical portion 06 which at one point is secured to the adjacent carriage end by the screw 94 and in another place by screw |01. The requirement for rightwardly and leftwardly displacing the lever 6I respectively in connection with effecting respectively a right and left margin stop adjustment is to avoid confusion in the mind of the operator. Indices R and L are provided in close proximity to the lever 6I, on a conventional part I4 carried by the right carriage end.

It has been said that the right margin stop iR cooperates with the counterstop 61 through the medium of an interponent 13. This interponent, see Figures 3 and 4, is a rearwardly bentofi part of a lever |08 which is pivotally carried on the margin stop IR by the stud 82, and the latter of which supports the spring drum 8|. Said lever includes a. weighted arm |09 always tending to keep the interponent 13 against the margin stop face 12. It will now be seen that whenever the margin stop IR has passed beyond line-end signalling position, the interponent 13. during an ensuing carriage return movement. will encounter the bell-ringing lever 15, but in doing so will swing idly thereover upwardly away from the margin stop face 12, wherefore the line-end signalling device will then not function.

The exible element 83 which extends between the spring drum and the left margin stop, just leftwardly of the drum, passes over a small sheave rotatively carried on aplate |I2 that is held fast on the margin stop IR by a shoulder of the screw stud 82.

The limits to which the margin stops are adjustable on the carriage are defined by abutment screws I I3 carried upon opposite ends of the carriage.

The invention is not limited to margin stop adjustment, but is broadly applicable to selective release of carriage stops by remote-control means in general, the broad principle residing in the provision for selective, remote-control release ol stops through rearrangements of such stops and rack means in transverse aspect to the direction in which the rack means extend. Moreover, the invention is capable of many embodiments without departing from the fundamental conceptions and features thereof.

What I claim is:

l. In a typewriting machine having a carriage movable on a frame; adjustable stop means for the carriage comprising, a bar extending parallel to the carriage, a stop carried on said bar for adjustment to different carriage stopping positions therealong, means to give said bar different rotative positions about an axis lengthwise of the bar, means extending lengthwise of said bar to confine said stop against rotation with the bar about said axis, rack means extending lengthwise on said bar, and tooth means on said stop respectively engageable and disengageable from said rack means by giving said bar different rotative positions about said axis, whereby said stop is adapted to be adjusted and locked in different positions lengthwise of said bar.

2. In a typewriting machine having a carriage movable on a frame. adjustable stop means for the carriage, comprising, a stop, a bar supporting said stop and having two rows of teeth therealong, the teeth of one row being of butti-ess form, dog means on said stop mounted for movement into and out of engagement with the rows of teeth, means biasing said dog means into engagement, the dog means in association with the buttress teeth being able to withstand heavy carriage arresting loads in one direction of carriage movement, and the dog means in association with the other row of teeth serving normally to detent the stop against displacement in the opposite direction, and means to turn said bar relatively to the stop about an axis extending lengthwise of the bar to cause said dog means to clear said rows of teeth and ride onto a bar surface which is smooth lengthwise of the bar, thereby to free the stop for adjustment.

3. In a typewriting machine having a carriage movable on a frame; adjustable stop means for the carriage comprising, a bar, two stops carried on said bar for individual adjustment to diierent carriage stopping positions therealong, means including a control means remote from said stops to give either of said stops relatively to said bar different positions about an axis which lies lengthwise of the bar, rack means lengthwise on said bar, and tooth means on each of said stops individually engageable and disengageable from the rack means respectively by giving said stops and bar different relative positions about said axis, whereby respectively to lock and release either of said stops for effecting an adjustment thereof along said bar.

4. In a typewriting machine having a carriage movable on a frame, adjustable stop means for the carriage, comprising, a bar, -two stops car- I'ied on said bar for individual adjustment therealong, counterstop means for said stops, said bar and said counterstop means being oppositely on the frame and the carriage, means including control means remote from said stops to give either of said stops relatively to said bar different positions about an axis which is lengthwise of the bar, rack means lengthwise on said bar, tooth means on each of said stops individually engageable and disengageable from the rack means respectively by giving said stop and bar said different relative positions about said axis, whereby respectively to lock and release either of said stops from the bar, and means to move the respective stops, as they are released, along the bar in one direction against the counterstop means.

5. In a typewriting machine having a carriage movable on a frame; adjustable stop means for the carriage, comprising, two stops, a common supporting bar for said stops, means pivotally supporting said bar, rack means on said bar, tooth means on each stop` normally cooperative with said rack means to lock the stops in individually adjusted positions along the bar, and control means associated with said bar to give it selectively one or another of two abnormal pivotal positions, in one of which the rack means frees the tooth means of one stop, and in the other of which the rack means frees the tooth means of the other stop whereby to facilitate adjustment of either one of the stops while the other stop remains locked lengthwise of the rod.

I6. In a typewriting machine having a carriage movable on a frame; two carriage arresting stops,

and means to support said stops so that said stops are selectively releasable for adjustment to diierent positions, comprising, unitary rack means extending parallel to the carriage, tooth means on each stop normally cooperating with said unitary rack means to hold each stop in individually adjusted position lengthwise of the unitary rack means, and means including control means remote from said stops to effect transversely of the unitary rack means, selectively one or another relative arrangement between the said tooth means and the unitary rack means, the tooth means of the individual stops being cooperatively arranged with respect to the unitary rack means so that in each of the two said transverse relative arrangements the tooth means of respectively only one or the other stop are freed from the unitary rack means.

7. In a typewriting machine having a carriage movable on a frame; two carriage arresting stops, counterstop means for said stops, said stops and counterstop means being oppositely on the frame and the carriage, a bar to support said stops selectively releasably for adjustment to diierent positions and having rack means extending parallel to the carriage, tooth means on each stop normally cooperating with said rack means to hold each stop in individually adjusted position lengthwise of the bar, means including control means remote from said stops to effect transversely of the bar, selectively, one or another relative arrangement between both the said stops and the bar inclusive of said rack means, the tooth means of the individual stops being cooperatively arranged with respect to the rack means so that in the two said transverse relative arrangements the tooth means of respectively only one or the other stop are freed from the rack means, and means to move said stops as each is released into abutting relation with the counterstop means.

8. In a typewriting machine having a carriage movable on a frame; two carriage arresting stops, and means to support said stops so that said stops are selectively releasable for adjustment to diierent positions, comprising, rack means extending parallel to the carriage, tooth means on each stop normally cooperating with said rack means to hold each stop in an individually adjusted position lengthwise of the rack. and means to displace said rack means transversely of its length, oppositely to one or another position, said rack means and tooth means being cooperatively arranged for the rack means when displaced to one of said positions to clear the tooth means of one stop, and for the rack means when moved to the other position to clear the tooth means of the other stop.

9. In a typewriting machine having a carriage movable on a frame; adjustable stop means for the carriage, comprising two stops, a common supporting bar for said stops, dog means on each stop resiliently urged toward the bar, said bar having rack means formed lengthwise therealong and said dog means being normally engaged in the rack means of the bar, and means including control means remote from said stops to give selectively either one of said stops relatively about the bar an abnormal position which will cause the dog means thereof to ride off the rack means onto a smooth Surface on the bar while the dog means of the other stop remains in stop holding engagement with the rack means.

l0. i'n a typewriting machine having a carriage movable on a frame; two carriage arresting stops, and a bar supporting said stops so that said stops are selectively releasable for adjustment to unerent positions, comprising, rack means extending parallel to the carriage, tooth means on each stop normally cooperating with said rack means to noia each stop in individually adjusted position lengthwise or the rack, and means to rock said rack means transversely of its length, oppositely to one or another position,

said rack means and tooth means being cooperative, for the rack means when rocked to said one position to clear the tooth means oi' one stop, anu roi the rack means when rocked to the other ptosition to clear the tooth means of the other s op.

11. In a typewriting machine having a carriage movable on a frame, two margin stops, and means to mount and adjust said margin stops, comprising, a common supporting bar for both said stops having lengthwise thereon one rack composed of buttress teeth and another rack composed of substantially square-shaped teeth, dog means on one stop associated with said irst rack, dog means on each one of said stops associated with said other rack, spring means to bias all said dog means toward the bar to engage normally their associated racks, thereby to hold such stops adjusted, and means to rock said bar oppositely to one or another abnormal position, the dog means associated with one stop 11 being disengageable by the rocking of the bar -t'o one abnormal position, and the dog means of the other stop being disengageable by the rocking of the bar to the other abnormal position.

12. In a typewriting machine having a carriage movable on a frame; two margin stops, and means to support and control said margin stops so that they are selectively releasable for movement to different margin dening positions, comprising, a control member remote from said stops and movable transversely of the carriage, oppositely to release selectively one or the other margin stop for adjustment, and means for mounting and restricting said control member to compel an operator to give it respectively a slight leftward or a slight rightward movement preparatory to moving it transversely of the carriage for releasing respectively one or the other margin stop.

13. In a typewriting machine having a carriage movable on a frame; a left and a right margin stop mounted on the carriage and selectively releasable for adjustment to different margin defining positions, and means to selectively release said margin stops, comprising, a control member at one end of the carriage capable of manipulation transversely of the carriage from a normal position oppositely to one or another abnormal position, thereby to release respectively one or the other margin stop, means to lend said control member capacity for some displacement on the carriage leftwardly and rightwardly against resilient resistance tending to restore it, and means to restrict said control member to necessitate giving it a deliberate leftward and a deliberate rightward displacement respectively preparatory to manipulating it to one or the other of said abnormal positions;

14; The invention set forth in claim 13, and said restricting means including means for blocking movement of the control member directly between the two said abnormal positions without the operator giving the control member a d'elib` erate leftward or' a deliberate rightward' displacement.

15- The invention set4 forth in claim 13, including meansto intercept and hold the 'control meinber upon its return to normal position, pending the impartatio'n thereto of a newy deliberate leftvvard or rightward displacement.

16. In a typewriting machine having a carriage movable on a frame;` adjustable stop means for the carriage comprising, arbar, a stopl'carried on said bar turnably relatively thereto about an axis lengthwise of` the barvfor adjustment of the stop to diierent carriage stopping positions along the bar, means to give said stop and bar 'diiierent relative positions about Said :axis from a location remote from said stop, said last means comprising, means to conne said stop normally against turning relatively to said bar, and means to give said confining means and said bar dii'erent relative positions about said axis, rack means extendinglengthwise on said bar; and tooth means on said stop respectively engageable and disengage- 6 able from said rack means by giving said confini- 12 ing means and said bar said different relative positions about said axis, whereby said stop is adapted to be adjusted and locked in different positions lengthwise of said bar.

17. In a typewriting machine having a carriage movable on a frame; adjustable stop means for the carriage comprising, a bar, a 'stop carried on said bar turnably relatively thereto about an axis lengthwise of the bai' for adjustment of the stop to dilerent carriage stopping positions along the bar, counterstop means for said stop, said stop and counterstop means being oppositely on the frame and the carriage, means to give said stop and bar diiferent relative positions about said axis from a location remote from said stop, said last means comprising, means to confine said stop normally againstturning relatively to said bar, and control means to give said conning means and said bar different relative positions about said axis, rack means extending lengthwise on said bar, tooth means on said stop respectively engageable and disengageable from said rack means by giving said confining means and said bar said dilerent relative positions about said axis, and means to move said stop automatically against said counterstop means as the tooth means of the stop is disengaged from the rack means. y

18. In a typewriting machine having a carriage movable on a frame; two margin stops, ,and means to support and control said margin stops so that they are selectively releasable for movement to diierent margin defining positions, comprising, a control member remote from said stops and movable transversely of the carriage, op-

positely from a normal position to release selectively one or the other margin stop for adjustment, means for mounting and restricting said control member to compel an operator to give it respectively a slight leftward or a slight rightward movement preparatory tomoving it trans'- versely of the carriage for releasing respectively one or the other margin stop, and spring-means to restore said control member to Anormal position whenever it is released after a stop releasing movement. o

v 19. A margin stop assembly for typewriters comprising a rod, means forrotatably supporting' the rod on and parallel with the carriage of a typewriter, a margin stop slidably mounted on the rod adapted tobe engaged by a carriage stop of the typewriter, resilient means normally urg; in'g the margin stop away from one end of the rod to the opposite end thereof, and means co-'acting between the margin stop andthe rod to lock the former on the latter; said rod being rotatable to` release the stop. v

WIBBIAM F. HELMOND.

References cited in the me of this patent UNITED STATES PATENTS Number Name Date 557,799 webb sept. 15, 189s gigs-,2tel webb June fr, 189s 2,303,065 Prezioso Nov. 24', 1942

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