US3720297A

US3720297A - Action and shift jam reset mechanism

Info

Publication number: US3720297A
Application number: US00136036A
Authority: US
Inventors: T Frechette
Original assignee: Litton Business Systems Inc
Current assignee: TRIUMPH-ADLER AG A CORP OF GERMANY; Western Atlas Inc
Priority date: 1971-04-21
Filing date: 1971-04-21
Publication date: 1973-03-13
Anticipated expiration: 1990-03-13

Abstract

A jam reset mechanism for an electric typewriter disengages a wrap spring clutch to uncouple a power source from a power roll when type bars or other driven mechanisms jam. The jam reset mechanism also imparts a rotational movement to the power roll in a direction counter to its normal direction of rotation to allow the drive pawls of the jammed type bars or other driven mechanisms to return to their inactive positions.

Description

ilnited States Patent n91 Frechette M lMarch 13, 1973 1 ACTION AND SHIFT JAM RESET MECHANISM [75] Inventor: Thomas E. Frechette, Windsor Locks, Conn.

[73] Assignee: Litton Business Systems, Inc., New

York,N.Y.

[22] Filed: April 21, 1971 [21] App1.No.: 136,036

[52] U.S. C1 ..197/17, 192/56 [51] Int. Cl. ..B4lj 23/08 [58] Field of Search ..197/17, 5S;192/26, 41 S, 56

[56] References Cited UNITED STATES PATENTS 3,616,887 11/1971 Anderson ..197/17 3,204,478 9/1965 Theiin 3,536,172 10/1970 Frechette 3,376,963 4/1968 Schaefer "192/26 X R25,024 8/1961 Barkdoil... 197/17 3,605,978 9/1971 Kawano i ..197/55 3,394,785 7/1968 Crutcher et a1 ..192/26 X Primary ExaminerRobert E. Pulfrey Assistant Examiner-R. T. Rader Attorney-Joseph R. Spala [57] ABSTRACT A jam reset mechanism for an electric typewriter disengages a wrap spring clutch to uncouple a power source from a power tell when type bars or other driven mechanisms jam. The jam reset mechanism also imparts a rotational movement to the power roll in a direction counter to its normal direction of rotation to allow the drive pawis of the jammed type bars or other driven mechanisms to return to their inactive positions.

4 Claims, 5 Drawing Figures PATENTFDHAR 1 3197s sum 1 BF 2 INVENTOR THOMAS E. FRECHETT E Y KE M ATTO R NEY llllll/[II/l/lllI/[IIIIII/I PATENIEUMAmms 3,720,297

SHEET 2 or 2 INVENTOR THOMAS FRECHETTE BYWRM I 11/ rill/11111111111111! BACKGROUND OF THE INVENTION The present invention relates to a jam reset mechanism for electric typewriters and more particularly to an improved jam reset mechanism which both disengages a motor from a power roll and allows the drive pawls of the typewriter to return to their inactive position.

Barkdoll, U.S. Pat. No. RE 25,024, issued Aug. ll, 1961 is of interest in that this patent discloses an electric typewriter having a motor which is coupled to a snatch roll through a speed responsive centrifugal clutch. The clutch disengages the motor from the snatch roll when mechanisms driven by the snatch roll become jammed and also causes a movement of the snatch roll to facilitate the resetting of the jammed mechanisms.

The present invention was specifically designed for an electric typewriter which utilizes a wrap spring clutch to couple the motor drive train to the power or snatch roll. The jam reset mechanism is used to uncouplc the motor of an electric typewriter from the snatch roll when components driven by the snatch roll become jammed and cause the snatch roll to stop. Thus the motor will not remain stalled and possible damage to the motor can be avoided.

The jam reset mechanism also imparts rotational movement to the snatch roll in a direction counter to its normal direction of rotation. This allows the drive pawls of the jammed type bars or other jammed com ponents to return to their inactive position.

SUMMARY Briefly, the jam reset designed to carry out the above mentioned functions is an interposer gear which is coupled to the wrap spring clutch of the drive train and actuated through a sector gear by a jam reset lever, The wrap spring clutch normally grips both sections of a split hub to couple a drive pulley with the snatch roll. When the interposer gear is rotated by the sector gear in a direction counter to the normal direction of rotation of the drive pulley and the snatch roll, the grip of the wrap spring clutch on the pulley section of the hub is loosened. This uncouples the drive pulley from the snatch roll so that the drive pulley can rotate independently.

At the same time that one portion of the wrap spring.

clutch is being disengaged from the pulley section of the hub, the other portion of the wrap spring clutch continues to grip the snatch roll section of the hub. Consequently, the wrap spring clutch imparts a limited rotational movement of the snatch roll in a direction counter to its normal direction of rotation. This move ment allows the drive pawls to become disengaged from the teeth, flutes or blades of the snatch roll so that the pawls can return to their inactive positions.

When the jam reset lever is depressed, a check pawl is moved into contact with the teeth of the interposer gear before the sector gear meshes with the interposer gear. If the machine is operating normally, this brings 1 The objects and advantages of the present invention will become apparent from the following detailed description and accompanying drawing of a preferred embodiment of the invention,

DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of the wrap spring clutch and jam reset mechanism of the present invention.

FIG. 2 is a side view, partially in section, of the jam reset mechanism in its inactive position.

FIG. 3 is a side view, partially in section, of the jam reset mechanism when it is fully actuated and the wrap spring clutch is disengaged.

FIG. 4 is a side view, partially in section, of the jam reset mechanism returning to the inactive position after the actuating lever has been released.

FIG. 5 is a side view, partially in section, of the jam reset mechanism which shows the check pawl engaging the interposer gear to prevent gear chatter when the mechanism is accidentally actuated.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring now to FIG. 1 there is shown a drive means in the form of a drive pulley 10, a wrap spring clutch, generally indicated at 11, a suitably journaled snatch roll, generally indicated at 14, and a jam reset mechanism, generally indicated at 16. These components, together with a motor which is not shown, make up a drive train for powering the drive pawls of type bars and other mechanisms of a typewriter. While blades 18 are shown on the snatch rolll4, it is to be understood that the snatch roll 14 can be toothed, fluted or have other equivalent means for engaging and driving the drive pawls.

The drive pulley 10 is coupled to an output shaft of the typewriter motor through a belt 20 which drives the pulley 10 in a counterclockwise direction. The pulley 10 is affixed to and rotates with an element or section 22 of a split hub generally indicated 24. The hub section 22, in turn, is rotatably carried on an extension of a snatch roll shaft 26. Thehub section 22 has a sleevelike extension 28 extending from one side thereof for receiving a portion of a coiled clutch wrap spring 30.

The snatch roll shaft 26 is provided with a collar which forms the other element or :section 32 of the split hub 24. The hub section 32 is affixed to the snatch roll shaft 26 by set screw 34, rotates with the snatch roll shaft 26 and is provided with a sleeve-like extension 36 which extends toward an abuts extension 28 of hub section 22. Extension 36 receives the other portion of coil spring 30. Normally this spring is so tightly wrapped about extensions 28 and 36 that the counterclockwise rotation of drive pulley 10 is transmitted through the clutch spring 30 to the snatch roll 14.

The clutch spring 30.has a tab 38 at one end which extends radially outward from the extension 28. This tab 38 is received within a slot 40 of a member of the jam reset mechanism 16. The member is in the form of an interposer gear, generally indicated 42, which is utilized to disengage the clutch wrap spring 30 from the extension 28 as will be fully explained hereafter.

The interposer gear 42 is rotatably mounted on the extension 28 with one-side thereof abutting a boss of the hub section 22. The interposer gear 42 has external teeth 44 and a sleeve 46 which extends toward hub section 32. The internal diameter of the sleeve 46 is greater than the external diameter of the extension 28 so that a portion of the coiled clutch spring 30 can be received intermediate the external surface of the extension 28 and the internal surface of the sleeve 46.

The sleeve 46 has the slot 40 therein. This slot 40 extends parallel to the axis of rotation of the interposer gear 42 and receives the tab 38 of the clutch spring 30 which urges the interposer gear 42 against the boss of the hub section 22. With this arrangement, when the interposer gear 42 is rotated in a clockwise direction the coils of the wrap spring 30 are expanded thereby disengaging the clutch 11 from the extension 28.

The interposer gear 42 is rotated in the clockwise direction by moving means of the jam reset mechanism 16 which includes a sector gear 48 which has teeth 50 that mesh with the teeth 44 of the interposer gear 42 when a jam reset lever, generally indicated 52, is depressed. The sector gear 48 is affixed to a shaft 54 which, although it is not shown, is suitably joumaled at each end to permit rotation of the shaft about its longitudinal axis.

The sector gear 48 has a first tab 56 thereon which is engaged by and driven downwardly by an intermediate lever, generally indicated 58, when the lever 52 is depressed. This effects a counterclockwise rotation of the sector gear 48 about the axis of shaft 54 thereby rotating the interposer gear 42 clockwise which expands the coils of the clutch spring 30.

The sector gear 48 has a second tab 60 which is coupled by a resilient biasing means in the form of a spring 62 to the chassis of the typewriter. This spring 62 together with clutch spring 30 tends to urge the sector gear 48 toward its inactive position so that when the jam reset lever 52 is released the sector gear 48 returns to its inactive position.

The intermediate lever 58 is pivotally mounted on a shaft 64 which passes through a flange 66 and a main lever arm 68 of the intermediate lever 58. The intermediate lever 58 has a tab 70 extending at right angles to the main lever arm 68. This tab 70 engages the underside of the jam reset lever 52 and is driven downwardly by the jam reset lever 52 when the jam reset lever 52 is depressed.

The jam reset mechanism is also provided with a check pawl generally indicated 72, which prevents gear chatter should the jam reset lever 52 be accidentally actuated. The check pawl 72 is pivotally mounted on the shaft 64 and is resiliently spring biased by a spring 74 toward engagement with the teeth 44 of the interposer gear 42. The check pawl 72 is also provided with a tab 76 which extends over and engages the upper edge of jam reset lever 52. The jam reset lever 52 normally maintains the check pawl in a disengaged position. However, when the jam reset lever 52 is depressed it no longer blocks the pivotal movement of the check pawl 72 and spring 74 then urges the check pawl 72 into contact with the teeth 44 of the interposer gear 42. The linkage is such that check pawl 72 engages teeth 44 before the sector gear 48 meshes with the interposer gear 42. This insures that the interposer gear 42 comes to a stop before it is engaged by the sector gear 48. Likewise upon release of lever 52, the check pawl 72 is disengaged prior to any movement of sector gear 48 so that the interposer gear 42 is free to return to its normal position relative to the extension 28.

Referring now to FIGS. 2 4, the operation of the jam reset mechanism will be explained. When the snatch roll shaft 26 comes to a halt due to the jamming of the type bars or other instrumentalities, the operator depresses the jam reset lever 52. This engages the check pawl 72 with the teeth 44 which prevents counterclockwise rotation of the interposer gear 42 and drives the sector gear 46 through its action stroke which effects a clockwise rotation of the interposer gear 42 to the position shown in FIG. 3. The clockwise rotation of the interposer gear causes the expansion of the coils of the clutch spring 30 which normally engage the extension 28. This uncouples the drive pulley 10 from the snatch roll 14, permits the drive pulley 10 to rotate and removes the motor from its stalled condition.

At the same time that the coils of the clutch spring 30 which normally engage the extension 28 are being ex panded, the other portion of the clutch spring 30 continues to grip the extension 36 of the hub section 32. Thus a limited clockwise movement is imparted to the snatch roll 14 thereby allowing the drive dogs of the jammed instrumentalities to return to their inactive position.

Upon the release of the jam reset lever 52, a spring 78 urges the jam reset lever 52 toward its normal position. The jam reset lever 52 contacts the tab 76 on its upward stroke and forces the check pawl 72 out of engagement with the interposer gear 42 as shown in FIG. 4. With the check pawl 72 disengaged, the interposer gear 42 is free to rotate in a counterclockwise direction. Consequently, the

springs

30 and 62 cooperate to return the interposer gear 42 to its normal operating position and the sector gear 48 to its inactive position.

Turning now to FIG. 5, the jam reset mechanism is shown with the jam reset lever 52 on the downward stroke and with the check pawl 72 engaging the teeth 44 of the interposer gear 42. With this arrangement, if the jam reset lever 52 (which can also serve as a margin release key) is accidentally depressed while the typewriter is running, the interposer gear is brought to a halt before the sector gear teeth 50 contact the teeth 44 of the interposer gear 42. This prevents a condition wherein the sector gear 48 could contact the rotating interposer gear 42 thereby causing gear chatter and possible damage to the gear teeth.

While a preferred form of the invention has been shown and described, it is to be understood that all suitable modifications and equivalents can be employed which fall within the spirit and scope of the invention as set forth in the following claims.

The invention claimed is:

1. In a typewriter having a rotatable power roll for operating powered typewriter mechanisms, drive means for rotatably driving the power roll, and a clutch including a first element connected to the power roll and a second element connected to the drive means and a coiled spring having first and second portions normally wrapped tightly about the first and second elements respectively to couple the power roll to the drive means for, the improvement comprising:

a jam reset member supported for rotation about said second element and fixedly engaging said first portion of said spring, and

jam reset moving means for rotating said jam reset member about said second element in a direction opposite to the coiling of said spring to expand said first portion of said spring about said first element so as to uncouple said drive means from said power roll and to rotate said second element in a direction opposite to said first direction so as to enable jammed typewriter mechanism to return to a rest position.

2. In a typewriter according to claim 1:

said jam reset member being in the form of a first gear rotatably supported about said first element,

said jam reset moving means including a second gear supported for movement into operative engagement with said first gear, a

resilient biasing means for normally urging said second gear from engagement with said first gear,

said jam reset moving means further including a lever pivotally supported and operably associated with said second gear, and

said lever being pivotally movable in one direction for moving said second gear into engagement with said first gear against the urging of said resilient biasing means to rotate said first gear about said first element.

3. In a typewriter according to claim 2, the combination further comprising:

a pawl supported for movement to engage said first gear and prevent rotation thereof about said first element in a normal direction,

another resilient biasing means for normally urging said pawl into engagement with said first gear,

said lever normally blocking the movement of said pawl into engagement with said first gear, and

said pawl being movable into engagement with said first gear prior to said second gear engaging said first gear upon pivotal movement of said lever in said one direction.

4. ln a typewriter according to claim 1:

said jam reset member being in the form of a gear rotatably supported about said first element,

a pawl supported for movement to engage said gear and prevent rotation thereof about said first element in a normal direction,

resilient biasing means for normally urging said pawl into engagement with said gear,

said jam reset moving means including a lever pivotally supported and movable in one direction for operating said moving means to effect rotational movement of said gear about said second element in a direction opposite to the coiling of said spring,

said lever normally blocking the movement of said pawl into engagement with said gear, and

said pawl being movable into engagement with said gear prior to the movement of said gear about said first element upon pivotal movement of said lever in said one direction.

Claims

1. In a typewriter having a rotatable power roll for operating powered typewriter mechanisms, drive means for rotatably driving the power roll, and a clutch including a first element connected to the power roll and a second element connected to the drive means and a coiled spring having first and second portions normally wrapped tightly about the first and second elements respectively to couple the power roll to the drive means for, the improvement comprising: a jam reset member supported for rotation about said second element and fixedly engaging said first portion of said spring, and jam reset moving means for rotating said jam reset member about said second element in a direction opposite to the coiling of said spring to expand said first portion of said spring about said first element so as to uncouple said drive means from said power roll and to rotate said second element in a direction opposite to said first direction so as to enable jammed typewriter mechanism to return to a rest position.

2. In a typewriter according to claim 1: said jam reset member being in the form of a first gear rotatably supported about said first element, said jam reset moving means including a second gear supported for movement into operative engagement with said first gear, resilient biasing means for normally urging said second gear from engagement with said first gear, said jam reset moving means further including a lever pivotally supported and operably associated with said second gear, and said lever being pivotally movable in one direction for moving said second gear into engagement with said first gear against the urging of said resilient biasing means to rotate said first gear about said first element.

3. In a typewriter according to claim 2, the combination further comprising: a pawl supported for movement to engage said first gear and prevent rotation thereof about said first element in a normal direction, another resilient biasing means for normally urging said pawl into engagement with said first gear, said lever normally blocking the movement of said pawl into engagement with said first gear, and said pawl being movable into engagement with said first gear prior to said second gear engaging said first gear upon pivotal movement of said lever in said one direction.