US2897942A - Carriage overbanking elimination - Google Patents

Description

Aug. 4, 1959 E. KEENE v CARRIAGE OVERBA'NKING ELIMINATION Filed Feb. 18, 1957 2 Sheets-Sheet l INVENTOR LESTER E, EENE M & BY

ATTORNEY 2 Sheets-Sheet 2 L. E. KEENE CARRIAGE OVERBANKING ELIMINATION Aug. 4, 1959 Filed Feb. 18, 1957 INVENTOR CARRIAGE OVERBANKING ELIMINATION Lester E. Keene, deceased, late of Wellesley, Mass, by Thelma Keene, executrix, Wellesley, Mass, assignor to Underwood Corporation, New York, N.Y., a corporation of Delaware Application February 18, "1957,Serial No. 640,809

2 Claims. (Cl.-197-63) This invention relates to typewriters and other ofiice machineswhich have a step feeding-carriage, and particularly deals with prevention'of overbanking, namely with provision whereby the step-feeding mechanism gains accurate control over the carriage following every carriage return whether effected softly or violently.

Typewriters particularly which embody an open rectangular carriage "frame and have a so-called front'rail margin regulating mechanism, for example 'the conventional Underwood standard'typewriter, 'have been prone to overbanking because-the rearward, heavy;platen-bearing portion of the carriage,iincidental to interception of the carriage by the front-rail margin mechanism may whip excessively beyon'dits true return .positionand therefore may cause the step-feeding mechanism to take control over the carriage one step'beyond the intended linestart position. In recent ye arsthe carriage of said Underwood standard typewriter and other partsof the machine have been cast of aluminum instead of'iron which has rendered such'parts subject to greater flexure, so that the stated problem has been greatly accentuated.

Efforts have been made previously to eliminate the stated overbanking trouble by the automatic projection of an element intothe wheel of a-carriage feed escapement to thereby arrest the whipping portion of the carriage. Such an effort is represented by the patent to Kurowski No. 2,184,746, dated December 26, 1939. However, it has been found that Kurowskis' structure, due to the flexing of certain parts under very extreme shocks will still'fail to accomplishits intended purpose.

According to the present invention the step-feeding mechanism is caused to take unfailingly accurate control over the carriage, not by 'a'pro'vision to'stop its whipping overtravel but'by a provision to permit a temporary yield to take place between the step-feeding mechanism and the carriage while the whipping action transpires. In this action the feed mechanism or'es'capement is not subjected to any undue strain and, as the carriage after flexure recovers its natural form, the step-feeding mechanism automaticallytakesaccurate charge over the carriage, causing it to 'have the exactly intended linestart position.

It is therefore a general object of the invention to provide an efficient andreliably operative mechanism which will assure the assumption by the letter feed mechanism of accurate position control over the carriage, sequential to each carriage return, no matter with what degree of vigor such return is effected.

It is particularly also an'objec t ofthe invention to provide for the assumption of such correct control in a typewriter which has the carriage return stop mechanism and the escapement mechanism offset with respect to each other transversely of the direction of carriage movement.

It is a further object to provide for the assumption of the accurate control of the carriage by -the letter-feed mechanism sequential to each efiected carriage return ited States Patent 'in a usual manner.

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without subjecting the letter-feed mechanism and its supporting structure at any time to undue strain.

Other objects and features of the invention will become evident as the description is read with reference to the accompanying drawings which illustrate a preferred embodiment of the invention.

In such drawings,

Figure 1 is a fractional front perspective view illustrating a typewriter carriage and certain frame-supported parts, including the device of the invention.

Figure 2 is a plan view of a typewriter showing the carriage in a strained condition which it may assume momentarily as a result of being suddenly intercepted by return-limiting margin stop means, the device of the invention functioning to assure subsequently correct position control by the escapement mechanism over the carriage to start a new line of typing.

Figure 3 is a fractional front view of a conventional carriage escapement mechanism, alongwith a portion of the device of the invention, all parts being in normal positions.

The invention is illustrated as embodied in an Underwood standard typewriter and now for the moment more specifically referring to Figure 2, the main, stationary,

framework of the typewriter includes two laterally spaced .side portions 12. Such side portions support a front guide-way 13 for a carriage '14. At the rear of the machine the framework supports a carriage-guide-rod 15,

parallel to the guide-way 13. The carriage 14 comprises a generally rectangular skeleton frame consisting of a from bar 16, a rear bar 17, and opposite end pieces 18. A platen roll "19 extends intermediate the carriage end pieces Hand -is turnably mounted thereon in a usual manner. The rear bar 17 of the carriage has" two spaced elements 20 secured thereto in'a downwardly reaching relation, and having guiding association upon the-rod 15 The front bar 16 of the carriage supports forwardly extending therefrom one or two rollers 21 to travel in a groove 2201? the guide-way 13.

Ausual spring drum or device indicated at 23, through a drawband 24', tends constantly to advance the carriage 14 leftwardlyin letter-feed direction. Advance of the carriage, however, is governed by a usual letter-feed control -mechanism which comprises a gear rack 25 on the carriage, and a gearpinion 26 in mesh with such rack and supported on'a fixed bracket29 coaxially with an escapement wheel 27. A usual escapement dog means 28 is associated with the escapement wheel to restrain normally the pinion 26 against allowing letter-feed advance of the carriage. Such dog means is of conventional design and is operable by the typing mechanism to cause the escapement wheel to step-feed the carriage. The escapement wheel 27 has also associated therewith apawl 30 to check it against reverse, clockwise rotation. A usual one-way pawl connection 31 provides for transmission of only carriage advance motion from the pinion -26 to the escapement wheel 27, such pawl having idle ratcheting action when the pinion is rotated in the reverse direction by the return movement of the carriage,

the escapement wheel 27 meanwhile being held by the check pawl 30.

It will' be noted that the gear rack 25 extends generally along the rear portion of the carriage and comprises, to-

gether with arms 32 and 33 that are respectively united with the left and the right ends thereof, a pivoted bail structure. The arms 32, 33 have coaxial pivotal support on the carriage respectively on a pin 34 and a headed stud 35, the arm 33 including a collar 37 whereby it is supported on the stud 35. A spring 36 associated with the arm-32 exerts a bias on the bail structure to keep the rack 25 normally in mesh with the pinion 26.

From Figure 2 it will be seen that the arms 32, 33,

and thus the stated rack-bail, have capacity for sliding movement parallel to the direction of movement of the carriage along the pin 34 and the stud 35. A compression spring 40 interposed between the collar 37 of the arm 33 and the right end piece 18 of the carriage, provides that normally the carriage 14 has a position relatively to the rack 25 established by the head of the stud 35 contacting a countersunk face 41 in the collar 37. This normal relative position prevails in the showing of Figure l, but not in Figure 2 wherein the carriage is strained. The strength of the spring 40 is such that the carriage ordinarily moves unitarily with the rack 25 in the just stated relation. Both of the bail arms 32, 33 have upward-reaching extensions ending in finger pieces 42 whereby the bail may be actuated to release the rack 25 from the pinion 26 for effecting quick changes in the position of the carriage.

The front bar 16 of the carriage has secured thereto in underlying, parallel relation, a margin stop supporting rack 43. On this rack 43 there is supported adjustably therealong a carriage return margin stop 44 and also a line-end margin stop 45, all substantially in accord with a patent to Kingsbury No. 2,725,136, dated November 29, 1955. The carriage return margin stop 44 includes a down-reaching tongue 46 for carriage return gaging cooperation with a counterstop arm 47, the latter being borne fast on a rod 48 substantially centrally of the machine framework. The rod 48 is slidably and rock- :ably mounted upon spaced brackets 50 on the framework of the machine, only one such bracket being shown. Two spaced downwardly bent ears 51 of a member 52 which is secured to the underside of the guide-way 13, confine the counterstop arm 47 for limited movement parallel to the carriage. A compression coil spring 53 borne on the rod 48 near its left end by acting on a collar 54 which is fast on the rod 48, urges the latter rightwardly to a limit determined by the right-hand car 51, as seen in Figure 1.

'Interposed between the margin stop tongue 46 and the counterstop arm 47 is an interponent finger 55 which constitutes part of a structure 56 which is accommodated upon the rod 48 for sliding movement therealong. A fork element 57 carried fast on the rod 48 keeps the sliding structure 56 from turning about such rod by having a sliding fit with a bar portion 58 of said member. The said sliding structure 56 may be said to have normally the position seen in Figure 1, wherein the interponent finger 55 stands about one letter-feed space leftwardly of the counterstop arm 47. Near the end of each return movement of the carriage, which may be eifected by operation of a usual line-space lever 60, the margin stop tongue 46 engages the interponent finger 55 and displaces the same, along with the sliding structure 58, rightwardly to a limit afiorded by the counterstop arm 47 This movement of the interponent finger 55 has been accomplished in Figure 2 and serves to actuate a train of mechanism for moving an arrester 61 into mesh with the gear pinion 26, to hold it and the feed rack stationary.

The arrester 61 is part of a slide 62 which is provided with slots 63 to slide on studs 64 that are fast on bosses of the escapement bracket 29. The slide 62 is connected to the rear end of a lever 65 by means of a link 66. An upright stud 67 on the left side portion 12 of the machine affords a pivot for said lever 65. A torsion spring 68 provided on the stud 67 exerts a clockwise bias on the lever 65 to give it normally the position seen in Figure 1 in which the slide 62 stands rightwardly positioned and in which the arrester 61 stands clear of the pinion 26. From Figure 1, it will be further noted that the sliding structure 56 stands normally leftwardly positioned on the rod 48. The connection between the lever 65' and the sliding structure 56 comprises a screw 71 which may be regarded a part of the sliding structure 56 and which reaches through a slot 70 provided in the front end of 4 the lever 65 and has a head 72 for transmittal of motion from the lever 65 to the sliding structure or vice versa.

It will now be seen that whenever the carriage is being returned, the front portion thereof becomes arrested consequential to the tongue 46 of the carriage return margin stop 44 meeting and displacing the interponent finger 55 against the counterstop arm 47. Moreover, depending on the speed and force with which the carriage is returned, the latter becomes strained and distorted to a varying degree. Namely, the rearward portion of the carriage whips out of normal relation with the front portion, as illustrated in full lines in Figure 2, the normal relation of the rear portion of the carriage being indicated in such figure by dot-and-dash lines 73. This distortion of the carriage ranges up to more than one letter-feed space and is of course very momentary inasmuch as the carriage recovers its natural shape immediately upon dissipation of the kinetic energy stored in the rear portion of the carriage. The rightward displacement of the sliding structure 56 by the margin stop 44 may amount approximately to one letter-feed space, and is transmitted over the lever 65 and the link 66 to actuate the an-ester 61 into mesh with the pinion 26, thus to bring such pinion and the rack 25 to a definite halt. Throughout the return of the carriage, the escapement wheel 27 remains stationary under the control of the pawl 30 and the dog means 28 in the normal position seen in Figure 3. However, the pinion 26, permitted by the one-way pawl connection 31, is turned clockwise by the carriage supported gear rack 25. At the instant in the return at which the margin stop tongue 46 meets the interponent finger 55, the teeth of the pinion 26 reach substantially a tooth-relation with the escapement wheel 27 as seen in Figure 3. During the movement of the interponent finger 55 rightwardly to contact the counterstop arm 47, the gear rack 25 drives the pinion 26 slightly more than one letter-feed space clockwise, and at the end of such movement the one-way pawl connection 31 will have just caught over another tooth of the pinion 26. Meanwhile, the arrester 61 becomes firmly seated in that tooth notch of the pinion 26 which has been moving downwardly toward it. Consequently, while the carriage, due to the shock of being arrested, becomes momentarily distorted, the pinion 26 is held firmly against rotation in both directions and the rack 25 is held stationary in the space position in which it is intended subsequently to hold the carriage for the first typing impression. The momentary distortion of the carriage has no effect on the position of the rack 25, inasmuch as the compression spring 40 associated with the rack bail allows freely the rightward whipping of the rear portion of the carriage without disturbing the position of the rack 25 or the escapement mechanism. As the carriage after dissiptation of the arresting shock recovers its natural shape, and while the pinion 26 and its associated rack are still held against rotation, the normal relation between the rack 25 and the carriage is automatically reassumed in which the face 41 on the collar 37 contacts the head of the stud 35. The pinion 26 continues to be held by the arrester 61 even after the relaxation of the operating power on the line space lever 60, because the carriage stays returned almost fully to the limit of the counterstop arm 47. Specifically, the carriage feed drum 23 advances the carriage very slightly from fully returned position in that the very slight play at the one-way pawl connection 31 is taken up. The arrester 61 moves clear of the pinion 26 under the urge of the spring 68 only as a result of a letter-feed operation of the escapement because only then can the sliding structure move leftwardly to the normal position seen in Figure 1. In the manner stated, the escapement mechanism takes unfailingly accurate control over the carriage at the end of any carriage return, whether effected softly or harshly, and at no time is there any undue strain exerted on any part of the relatively delicate escapement mechanism and its supporting structure.

There is associated with the rod 48 a margin release key 74. A spring 75 urges this key upwardly to the normal position seen in Figure 1. The key, by a link 76, has connection with an arm 77 fast on the rod 48 so that the counterstop arm 47 and the interponent finger 55 reside normally in the range of the margin stops 44, 45. At this point it will be remembered that the sliding structure 56 which includes the interponent finger 55 is controlled by the fork 57 to turn with the rod 48. To allow movement of the carriage beyond the positions defined by the margin stops 44, 45, the operator depresses the margin release key, whereby the counterstop arm 47 and the sliding structure are turned, placing such arm and the interponent finger 55 below operative relation with the margin stops. The slot 70 in the lever 65 is arranged circularly around the axis of the rod 48 to permit the stated turning of the sliding structure 56.

Close to the left end of the rod 48, a bell crank element 78, pivoted at 80, is associated with the rod 48 for operation thereby. Specifically, when the line-end margin stop 45 encounters the counterstop arm 47 it will displace it andthe rod 48 leftwardly to actuate the stated bell crank 78. This is to operate a line-end key-lock of conventional construction, not shown.

It will be understood that the broad concept of the invention lies in a means which will automatically become effective to hold the escapement mechanism for the carriage in a correct potential carriage advance controlling state as the carriage in its return reaches a certain position, in combination with resilient means arranged intermediate the escapement mechanism and the carriage to allow temporary overtravel of at least a portion of the carriage without disturbing said state of the escapement mechanism, thereby to provide for the assumption of accurate escapement control over the carriage as the returning force on the carriage ceases.

Thus, although the invention has been described with reference to the details shown in the drawings, it is to be understood that it is susceptible to modification and change, and comprehends other construction and details within its general concept and purposes.

What is claimed is:

1. In a typewriting machine having a main frame, in combination, a carriage mounted on said frame to travel oppositely in a letter-feed and a return direction and being impositively urged in said letter-feed direction, letter-feed control means for said carriage comprising a member having teeth at regular intervals congruent with required letter-feed steps of the carriage, means connecting said carriage with said member to letter-feed in synchronism therewith and letter-feed escapement means, adjustable marriage-return limiting means for said carriage, said limiting means and said connecting means associated with carriage portions which are offset with respect to each other transversely of the direction of travel of the carriage, and means operated by the carriage late in its return approach to the position whereat said limiting means becomes effective, to engage the teeth of said member and thereby to bring said member to rest in a definite position related to the return limit afforded by said limiting means, said connecting means comprising a resilient provision allowing return overtravel of the carriage portion thereat independently of said member, the carriage being of light structure so that the portion thereof associated with said connecting means is subject momentarily to carriage-flexing overtravel at the conclusions of returns through the assertion of stored momentum thereof as the portion of the carriage which is associated with said limiting means becomes arrested.

2. In a typewriting machine having a main frame, the combination With a carriage mounted on said frame to travel oppositely in a letter-feed and a return direction, being impositively urged in said letter-feed direction, said carriage comprising a front bar, a rear bar and ends connecting said bars, of letter-feed control means for said carriage comprising a member having teeth at regular intervals congruent with required letter-feed steps of the carriage, means connecting said carriage at the proximity of said rear bar with said member to letterfeed in synchronism therewith and letter-feed escapement means, adjustable carriage return limiting means associated with the front bar of said carriage, means operated by the carriage late in its return approach to the position whereat said limiting means becomes efiective, to engage the teeth of said member and thereby to bring said member to rest in a definite position related to the return limit afforded by said limiting means, said connecting means comprising a resilient provision allowing return overtravel of the carriage portion thereat independently of said member, such carriage portion being subject to carriage flexing overtravel momentarily at the conclusions of returns by the assertion of stored momentum therein as said front bar becomes arrested by said limiting means.

References Cited in the file of this patent UNITED STATES PATENTS 1,456,296 Barney May 22, 1923 2,039,245 Gorin Apr. 28, 1936 2,184,746 Kurowski Dec. 26, 1939

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