US3889795A - Removable cartridge for the inked ribbon for typewriters, calculating machines or other office machines - Google Patents

Abstract

A removable cartridge for an inked ribbon for an office machine comprises a container rotatably supporting two ribbon-carrying spools. The container has a first side wall provided with a pair of slits for the passage of the inked ribbon from the one to the other of said spools. A pair of apertures in a second side wall opposite to said first side wall allows entry into said container of sensing elements of a ribbon reversal feed mechanism for sensing the amount of inked ribbon on said spools. The sensing elements cooperate with corresponding latch levers of a reversal member which, by means of a reversal spring actuates a feed element for driving the spools carrying said ribbon in one sense and the other sense respectively. A closure member of the machine is movable between a first position wherein the cartridge is held on the machine, and a second position wherein the sensing elements are withdrawn from said apertures.

Description

United States Patent Garberi et a1.

1 1 REMOVABLE CARTRIDGE FOR THE INKED RIBBON FOR TYPEWRITERS, CALCULATING MACHINES OR OTHER OFFICE MACHINES [75] Inventors: Sergio Garberi; Lorenzo Bertino,

both of lvrea. Italy {73] Assignee: Ing. C. Olivetti & C., S.p.A.,

IvrealTorino), Italy [22] Filed: Oct. 20, 1972 [21] Appl. No: 299,379

[30] Foreign Application Priority Data Dec. 6, 1972 Italy 70,460/71 Dec. 30. 1972 Italy 68,360/72 [521 US. Cl 197/151; 197/161 (51] Int. Cl B41j 33/14 [58] Field of Search ..197/151,160,161,l62,

[56] References Cited UNITED STATES PATENTS 111115.594 1/1912 Spurgin 197/151 1,871,232 8/1932 Foster 197/151 UX 1,944.023 l/1934 Ford 197/151 UX 2,825.450 3/1958 Lambert 197/151 X 2,902,136 9/1959 Whippo 1971165 3,349,887 10/1967 Goff 3,425,532 2/1969 Dannatt 197/151 June 17, 1975 11,513,957 5/1970 Ricciardi et al. 197/151 3,604.549 9/1971 Caudill et a1. 197/151 3,632.052 1/1972 Read 197/151 UX 3,643,779 2/1972 Anderson et a1. 197/151 Primary Examiner-Ernest T. Wright, Jr. Allorney, Agent, or FirmSchuyler, Birch, Swindler, McKie & Beckett [57] ABSTRACT A removable cartridge for an inked ribbon for an office machine comprises a container rotatably supporting two ribbon-carrying spools. The container has a first side wall provided with a pair of slits for the passage of the inked ribbon from the one to the other of said spools. A pair of apertures in a second side wall opposite to said first side wall allows entry into said container of sensing elements of a ribbon reversal feed mechanism for sensing the amount of inked ribbon on said spools. The sensing elements cooperate with corresponding latch levers of a reversal member, by means of a reversal spring actuates a feed element for driving the spools carrying said ribbon in one sense and the other sense respectively. A closure member of the machine is movable between a first position wherein the cartridge is held on the machine, and a second position wherein the sensing elements are withdrawn from said apertures.

17 Claims, 8 Drawing Figures PATENTEDJUN17 I975 889.795

PATENTEDJUN 17 ms SHEET Fig.4

PATENTEDJUN 17 ms SHEET Fig.7

REMOVABLE CARTRIDGE FOR THE INKED RIBBON FOR TYPEWRITERS, CALCULATING MACHINES OR OTHER OFFICE MACHINES BACKGROUND OF THE INVENTION The present invention relates to a removable cartridge for the inked ribbon for typewritters, calculating machines or other office machines. comprising a container and two ribbon-carrying spools rotatable therein in either direction. the container having at least one main wall to which the axes of both spools are perpen dicular. a series of side walls perpendicular to the main wall and a pair of slits in one of the side walls for the passage of the inked ribbon from the one of the other of the spools along a path which, between the slits, lies outside the container.

Cartridges for an inked ribbon are known which are provided with a closed container. in which the ribboncarrying spools rotate in both directions under the action of a reversal mechanism. The reversal mechanism of the machine is provided with a pair of sensing elements fulcrumed internally on the entrainment pins for the spools. Each sensing element is thrust from the inside against the ribbon coils wound on to the spool, through an aperture in the pin and an aperture in the core of the spool. The sensing elements then control the reversal of the movement of the ribbon. when the number of coils of wound ribbon on a spool is no longer sufficient to hold the sensing element in. The use of senser elements of this type, however. makes the reversal mechanism for the ribbon rather complicated and costly to realise.

Also known are typewriters which are provided with a reversal mechanism for the movement of the ribbon controlled by a sensor element which rests from the outside on the ribbon coils of the feed spool or of the take-up spool. The sensor element thus tests the quantity of wound ribbon, ordering the reversal when this quantity is less than a pre-established minimum number of coils, or else when it is greater than a maximum of coils which is likewise pre-established. This reversal mechanism is very simple and therefore economical, but requires, for the replacement ofa used ribbon, that the sensor element be pulled away from the relative spool. so as to allow the spool to be pulled off its pin. It is therefore not possible to use ribbon-carrying cartridges of known type, which have closed containers that do not allow the use of sensor elements which test externally the quantity of ribbon wound on the spools.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a removable cartridge for the inked ribbon for an office machine, comprising a container and two ribboncarrying spools rotatable therein in either direction of rotation. the container having at least one main wall to which the axes of both spools are perpendicular, a series of side walls perpendicular to the main wall, a pair of slits in one of the side walls for the passage of the ribbon from the one to the other of the spools along a path which, between the slits. lies outside the con tainer, and a pair of apertures in a side wall opposite the said one wall, each ofthe said apertures being associated with one of the spools and being adapted to allow entry into the container of sensing elements for sensing the amount of inked ribbon on the spools.

The invention further provides an office machine incorporating such a cartridge, means releasably attaching the cartridge to the machine, and a ribbon reversal mechanism including two sensing elements which enter the two apertures respectively and bear against the inked ribbon on the two spools respectively.

The closure member can comprise a closure member pivotally mounted on the machine for movement between a first position in which it holds the cartridge on the machine and a second position in which the cartridge is free to be taken off the machine. the closure member being arranged to act on the sensing elements through a coupling mechanism such that, when the clo sure member is in the second position, the sensing elements are withdrawn from the apertures.

The cartridge in accordance with the invention is simple and economical. This cartridge allows use of a simple attaching means and a simple reversal mechanism for the movement of the ribbon which, in combination with the cartridge, realise an economical and reliable whole.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the invention is described by way of example in the following description with reference to the accompanying drawing, in which:

FIG. 1 is a partial plan view of a cartridge for the inked ribbon embodying the invention and of a detail of a calculating machine on which the cartridge is mounted;

FIG. 2 is a partial section in accordance with the line II-Il of FIG. 1:

FIG. 3 is a partial section in accordance with the line III-lll of FIG. 1;

FIG. 4 is a partial plan view of the cartridge in a special position of the detail of FIG. 1;

FIG. 5 shows a partial plan view of the cartridge of FIG. 1 with another detail of the calculating machine;

FIG. 6 shows a section in accordance with the line VI-VI of FIG. 5;

FIG. 7 shows a section in accordance with the line VIIVII of FIG. 6 of some details of FIG. 5;

FIG. 8 shows the details of FIG. 7 in a second operative position.

DESCRIPTION OF A PREFERRED EMBODIMENT With reference to FIG. I, the cartridge 6 for the inked ribbon 12 comprises a container 5 of plastic material having a substantially parallelepipedal shape. The container 5 is provided at the rear side arms, two arm 7 which embrace a cylindrical writing head 8 of a calculating machine. The head 8 is movable between the arms 7 from a position of rest indicated in a solid line to an end-of-line position indicated in chain-dotted lines, in order to write a line of print on a tally roll 9 (FIG. 2). An inked ribbon 12 (FIG. I) is tensioned between the ends of the arms 7 which are suitably shaped and inclined to present the ribbon l2 parallely to the line of print on the tally roll 9 (FIG. 2) and at the right angle (FIG. 1) with respect to the ribbon l2 emerging from the container through two slits 11 adjacent the arms 7.

The container 5 is closed at the top by a lid 17 and has. in the rear part, a central recess which defines a space 13, which is connected to a space 14 (FIG. 3) formed by a channellike depression in the lid I7. The container 5 (FIG, 1) is provided, in the front side, with a central recess which forms a space 21 and with two apertures 22 and 23 through its front side wall. The container 5 also has central ribbing 24, in line with the spaces 13, 14 and 21, which divides it into two equal chambers. in which two spools 18 and 19 are rotatably mountedv The spools 18 and 19 store the wound inked ribbon 12 and rotate in the container 5 so as to convey the ribbon 12 from the one spool to the other over the arms 7 and through the slits 11. Each spool 18 and 19 has the shape of a cup turned upside down and is provided with a central holc surrounded by a toothed crown 26 or 27 respectively.

The crowns 26, 27 have three teeth which are lodged in a hole 28 (FIG. 3) or 29 respectively, formed in a lower portion 16 of the container 5. The hole 28 or 29 is defined by a sleeve 31 or 32 which protrudes inside the container 5. On each sleeve 31, 32 there normally rests the base of the spool 18 or 19.

The container 5 has, on its walls 33 and on the central ribbing 24, lugs 34 (FIG. 1) which engages in as many slots 36in the lid 17, in order to fix the lid 17 to the container 5. Internally the lid 17 has hemispherical pips 37 and 38 (FIG. 3) overlying the spools 18 or 19. The pips 37, 38 are arranged at l one to the other and do not allow the spools 18, 19 to rise from the re spective sleeves 31, 32 during the rotation for the advance of the inked ribbon 12.

Two revolving shafts 41 and 42 are mounted on a horizontal base 43 of the machine. The shafts 41 and 42 are connected to an advance and reversal device for the movement of the inked ribbon 12 contained inside the base 43 and which will be described subsequently. These shafts 41 and 42 are shaped at the top so as to have in their ends three incisions in the form of an inverted pyramid 44 or 46 respectively (FIG. 1) capable of engaging with the teeth of the crowns 26 and 27 presented by the spools l8 and 19 respectively.

Above the base 43 (FIGv 2) and fixed thereto there is arranged a horizontal platform 47, on which rests the cartridge 6. Fixed on the platform 47 there is a pin 48, about which there are fulcrumed two sensing elements 49 and 51 (FIG. 1) of the reversal mechanism for the inked ribbon 12. These sensing elements 49, 5] comprise a pair of scissor levers 52 and 53 which, under the action of a spring 54, normally rest on the inked ribbon 12 wound on the spools 18 and 19, at the same time keeping the coils tight on the spools 18 and 19. The spring 54 is fixed with its ends in corresponding 19. The spring of the levers S2 and 53 and is tensioned at its central portion round the pin 48.

Fixed on the sensing elements 49 and 51 are corresponding pins 56 and 57, which cooperate through slotted holes 58 and 59 in the platform 47 with a latch lever 121 or 122 (FIG. 7) of the mechanism for control of the reversal of the movement of the inked ribbon 12 contained in the base 43. Each sensing element 49, 51 (FIG. 1) has a tongue 61, 62 respectively, with which a releasing device 63, 64 respectively can cooperate. The two releasing devices 63, 64 are fulorumed on the platform 47 and each has a projection 66, 67 respectively, capable of cooperating with a cam 68, 69 respectively. These cams 68 and 69 are constituted by lugs projecting at the bottom and on the front side of a closure plate 71 of an inverted *T shape.

The closure plate 71 is made of plastic material and is pivoted on two pins 72 on two tongues 73 of the platform 47. The closure plate 71 can thus be swung up to the open, broken line position of FIG. 2. In its front edge the closure plate 71 (FIG. 2) has a central projection 74, in which there is made a V" incision 75 capable of cooperating with a leaf spring 76 integral with the platform 47, when the closure plate 71 is rotated by into the open position.

The closure plate 71 includes on the rear side a tongue 77, which is lodged in the space 14 (FIG. 3) of the lid 17, and a lower projection 78 keeps the cartridge 6 in contact with the platform 47.

The tongue 77 ends with a downwardly bent projec tion 79 (FIG. 2) in the form of a V which is lodged in the rear space 13 of the container 5. The projection 79 has, at the rear, a detent lug 81 capable of engaging with a shoulder 82 presented by a tongue 83 of the platform 47. The projection 79 has, furthermore, a rear ledge 84 substantially coplanar with the tongue 77 by means of which, taking advantage of the elasticity of the material, and by exerting a slight manual pressure. one can engage or disengage the detent lug 81 from the shoulder 82. The space 13 of the container 5 allows the tongue 83 to remain substantially aligned with the rear wall of the container 5 (FIG. 1) and outside the zone of rectilinear movement of the head 8.

To replace a used cartridge 6 by a new one, one acts in the following manner. With one hand one exerts a slight pressure on the ledge 84 (FIG. 2) of the projection 79 in order to disengage the detent lug 81 from the shoulder 82 and then one swings up the closure plate 71. The cams 68 (FIG. 1) and 69 bear against the respective projections 66 and 67 of the releasing devices 63 and 64 respectively. causing these devices 63 and 64 to rotate, the first device 63 in the clockwise direction and the second device 64 in the anticlockwise direction. Each releasing device 63, 64 engages the tongue 61 and 62 of the respective sensing element 49, 51. The two sensing elements 49, 51 rotate, the first sensing element 49 in the anticlockwise direction and the second sensing element 51 in the clockwise direction against the action of the spring 54.

After a rotation of about 90 of the closure plate 71, the leaf spring 76 engages in the incision 75. The releasing devices 63 and 64 have rotated the levers 52 and S3 of the sensing elements 49 and 51 out of the container 5, arranging them aligned in accordance with one and the same plane parallel to the shafts 41 and 42 as shown in FIGv 4. The closure plate 71 is then in the vertical position and the sensing elements 49 and 51 are disconnected from the cartridge 6, allowing the removal from the platform 47 of the cartridge 6.

The used cartridge 6 is then lifted off with one hand and is replaced by another one by resting this latter on the platform 47 so as to bring the crowns 26 and 27 (FIG. 1) into engagement with the shafts 41, 42. One then flaps down the closure plate 71 overcoming the resistance of the leaf spring 76.

The spring 54 causes the sensing elements 49 and 51 to rotate, the first sensing element 49 in the clockwise direction and the second sensing element 51 in the anticlockwise direction. The levers 52 and 53 pass through the apertures 22 and 23 of the container 5 and rest on the coils of inked ribbon 12 wound on the two spools l8 and 19. By now exerting a slight pressure downwards on the ledge 84 of the projection 79, the detent lug 81 snaps under the shoulder 82 of the tongue 83 (FIG. 2). The lower projection 78 of the tongue 77 is lodged in the space 14 (FIG. 3) of the lid 17 and keeps the cartridge 6 against the platform 47 through the elasticity of the tongue 77, and therefore in this way fixed removably to the machine. The two releasing devices 63 and 64 (FIG. I) rotate loosely and remain inactive during the functioning of the reyersal mechanism for the inked ribbon 12.

During the change of the cartridge 6, the stretch of inked ribbon 12 which projects out from the arms 7 is not in tension. because the spools l8 and 19 may have been rotated slightly in the clockwise or anticlockwise direction by the incisions 44 and 46 during the engagement with the crowns 26 and 27. Nevertheless. no sooner does the writing cycle begin than the inked ribbon 12 is brought rapidly into tension. During the fenctioning the levers 52 and 53 exert a certain restraining pressure on the coils of the inked ribbon 12.

With reference to FIG. 5, the reversal mechanism for the feed movement of the inked ribbon 12 comprises a series of flat gears 104, 106, I07. 108, 109 and 111 always in mesh one with another. The gear 104 is integral with a driving shaft 112 ofthe calculating machine, always revolving in the anticlockwise direction. The gears 106, 108 and 109 are rotary on axes 113 fixed below the platform 47 (FIG. 6). The gears 107 and 111 are rotary on slee\ es 114, they too fixed at the bottom to the platform 47. Two gears 116, 117, similar to the gears 111 and 107 respectively. are in one piece with the shafts 41 and 42 respectively, which are rotatable in the sleeves [14. The gears 116 and 117 are arranged below the gears III and 107.

Each sensing element 49, 51 is adapted to cooperate through its pin 56 or 57 with a tongue 118 or 119 respecti ely ofthe corresponding latch lever 121 or 122 (FIG. I both levers 121 and 122 being fuIcrumed on a pin 123 fixed on the base 43. A coil spring 124, fitted over the pin 123, has its ends bearing against the tongues 118 and 119 so as to thrust the lever 122 in the clockwise direction and the lever 121 in the anticlockwise direction about the pin 123. Under the action of the coil spring 124, each tongue 118, 119 will be arrested either on a front shoulder 128 or 129 respectively or on a rear shoulder 120 or 125 respectively of a reversal member 131.

The reversal member 131 is constituted by a rocker fulcrumed on a pin 132 fixed on the base 43. The rocker 131 can move from a first position shown in FIG. 7 to a second position shown in FIG. 8 and vice versa, under the action of a coiled expansion spring 133. The rocker 131 (FIG. 7) has two lugs 134 and 136 on each of which there is loosely revolving a pinion 137 or 138 respectively. Each pinion 137, 138 is capable of engaging selectively with the gear 111 (FIG. 6) or with the gear 107, in order to connect the gear 111 with the gear 116 and the gear 107 with the gear 117.

The rocker 131 is provided with two arms 139 (FIG. 7) and 141, each of which has a tongue 142 and 143 respectively. Each tongue 142, 143 can cooperate with a cam part 144 or 146 respectively ofa reload element 147.

The reload element 147 is constituted by a sliding plate having a generally rectangular shape and which rests on the bottom of the base 43. The reload element 147 has two windows 148 and 149 in which there are formed rack teeth 151 or 152 respectively arranged in the same horizontal plane. The teeth 151, 152 can en gage with a pinion 153 or 154 respectively which is in one piece with the shaft 41 or 42 respectively and hence with the gear 116 or 117 respectively.

The coiled expansion spring 133 is connected at one end to the rocker 131 and at the other end to the reload element 147. In the first position of the rocker 131 and of the reload element 147 of FIG. 7, the tongue 118 of the lever 121 is stopped against the front shoulder 128, whilst the tongue 119 of the lever 122 is stopped against the rear shoulder 125 of the rocker 13]. The tension of the coiled expansion spring 133 is such as to keep the rocker 131 stopped with a lateral shoulder 127 against the tongue 119. The reload element 147 is, in its turn, urged by the coiled expansion spring 133 against two stops 156 and 157 of the base 43 and with the pinion 153 adjacent to but disengaged from the teeth 151. In the second position of the rocker 131 and of the reload element 147 of FIG. 8, the tongue 118 of the lever 121 is stopped against the rear shoulder and the tongue 119 is stopped against the front shoulder 129. The tension of the coiled expansion spring 133 keeps the rocker 131 stopped with a lateral shoulder 126 stopped against the tongue 118. The reload element 147 is, in its turn, stopped against two fixed stops 158 and 159 of the base 43 and with the pinion 154 adjacent to but disengaged from the teeth 152.

In operation it will be assumed that the rocker 131 and the reload element 147 are in the first position as shown in FIGS. 5, 6 and 7, in which the pinion I37 meshes with the gears I11 and 116. The gear train from 104 to 111 then causes the ribbon 12 to wind on to the spool 18, whereby the ribbon l2 shifts from the right to the left in FIGS. The lever 52 withdraws the pin 56 from the tongue 118 against the action of the spring 54. On the contrary, the pin 57 of the lever 53 approaches the tongue 119 under the action of the spring 54. The inked ribbon 12 continuing to unwind from the spool 19, the lever 53 progressively approaches towards the center of the spool 19 whereby the pin 57 engages the tongue 119 and begins to cause the lever 122 (FIG. 7) to rotate in the anticlockwise direction against the action of the coil spring 124, over which the spring 54 (FIG, 5) prevails. When the coils of inked ribbon 12 wound on the spool 19 are less than a prefixed quantity, the tongue 119 disengages from the lateral shoulder 127 (FIG. 7), whereby the coiled expansion spring 133 causes the rocker 131 to rotate rapidly in the anticlockwise direction. The rocker 131 passes from the first po sition to the second one, placing itself in the position shown by broken lines in FIG. 7. The tongue 118 in its turn, under the action of the coil spring 124, then stops on the rear shoulder 120, whilst the tongue 119 remains rested against the pin 57, until the coils of inked ribbon 12 (FIG. 5) increase on the spool 19, whereby the lever 53 draws away radially and therefore the tongue 119 engages the front shoulder 129 (FIG. 8). The pinion 137 ceases to engage the gears 111 (FIG. 5) and 116, thereby stopping temporarily the shaft 41. The pinion 138 then meshes with the gears 107 and 117, whereby the shaft 42 can rotate.

At the same time the tongue 143 (FIG. 7) ceases its engagement with the cam part 146 and the tongue 142 engages with the cam part 144. The coiled expansion spring 133 assumes a second position shown in broken lines, causing the reload element 147 to shift backwards until this latter is stopped against the fixed stop 158 as shown in broken lines in FIG. 7. The teeth I52 therefore come into mesh with the pinion 154.

Because of the rotation of the gears from 104 to 107 (FIG. the pinion 138 transmits the movement to the gear 117, and thence to the shaft 42, whereby the inked ribbon 12 starts to wind on to the spool 19. At the same time the pinion 154 (FIG. 7). which is rotating in the anticlockwise direction, meshes with the teeth 152 and shifts the reload element 147 towards the right until it stops against the fixed stop 159. During this displacement. the tongue 142, through the cam part 144. shifts the left hand end of the reload element 147 forwards, so as to prevent the teeth 151 from encountering the teeth of the pinion 153. With this displacement, the various elements assume the stable configuration of FIG. 8 already described, whereby the coiled expansion spring 133 now tends to urge the rocker 131 back from the position of FIG. 8 to that of FIG. 7.

The inked ribbon 12 (FIG. 5) continues to wind on to the spool 19, whereby the lever 53 moves radially against the action of the spring 54. drawing away from the center of the spool 19 and drawing the pin 57 away from the tongue 119. The lever 52 moves on the con trary radially under the action of the spring 54 towards the center of the spool 18 and moves the pin 56 towards the tongue 118. Eventually the pin 56 engages the tongue 118. causing the lever 121 (FIG. 8) to rotate in the clockwise direction against the action of the coil spring 124 until the tongue 118 ceases to engage the lateral shoulder 126. The coiled expansion spring 133 then causes the rocker 131 to rotate rapidly in the clockwise direction. thereby to pass from the second position to the first position as shown by broken lines in the FIG. 8. The coiled expansion spring 133 assumes the position shown in broken lines in FIG. 8.

The pinion 138 disengages from the gears 107 and 117 (FIG. 5). whereby the shaft 42 ceases to rotate, and the pinion 137 meshes with the gears 111 and 116. The tongue 142 (FIG. 8) disengages from the cam part 144 whilst the tongue 143 engages the cam part 146. The coiled expansion spring 133 shifts the reload ele ment 147 backwards untii it stops against the stop 156 as shown by broken lines in FIG. 8. The teeth 151 mesh with the pinion 153. The tongue 119, under the action of the coil spring 124, engages with the rear shoulder 125, whilst the tongue 118 remains rested against the pin 56, until the coils of inked ribbon 12 (FIG. 5) wound on the spool 18 increase, when the lever 52 withdraws radially and hence the tongue 118 engages the front shoulder 128 (FIG. 8).

Through the rotation of the gears from 104 (FIG. 5) to 111, the pinion 137 transmits the movement to the gear 116 and hence to the shaft 41 whereby the inked ribbon 12 resumes its winding on the spool 18. At the same time the pinion 153 (FIG. 8), by rotating in the clockwise direction, meshes with the teeth and shifts the reload element 147 until it stops against the fixed stop 157. During this displacement the tongue 143, engaging the cam part 146. moves the right hand end of the reload element 147 forwards so that the teeth 152 do not encounter the teeth of the pinion 154. The various elements therefore resume the stable con figuration of FIG. 7.

We claim:

1. A removable cartridge for an inked ribbon for an office printing machine of the type including a supporting platform. two motive shafts rotatably projecting from said platform. a ribbon reversal feed mechanism including two sensing elements for rotating one or another of said two motive shafts in one predetermined sense of rotation, a closure plate including a central tongue. an engaging tongue projecting from said platform, said closure plate being fulcrumed on said platform between an inoperative location and an operative location for causing said central tongue to engage said engaging tongue in correspondance with said operative location of said closure plate. and means connecting said closure plate with said two sensing elements for moving said sensing elements from inoperative positions away from said motive shafts in correspondence with said inoperative location of said closure plate of operative positions of said sensing elements near said motive shafts, in correspondence with said operative location of said closure plate. said cartridge comprising a. a container including a main wall. a series of side elements connected to said main wall perpendicular to said main wall, two ribbon spools, means rotatably supporting said spools in lateral spaced relation within said container about an axis perpendicular to said main wall. means for accomodating said motive shafts concentrically with said spools. and an inked ribbon having ends fixed to said spools and wound in coils on said spools. one of said side elements defining a pair of slits for the passage of said inked ribbon from the one to the other of said spools outside said container, and said spools being provided with corresponding engaging means for engaging said motive shafts;

b. aperture means on said container for causing said sensing elements during the movement thereof from said inoperative positions to said operative positions to bear against said coils of ribbons wound on said spools, and sense the amount of coils of ribbon wound on said spools; and

c. first means defining a recess between said two spools in said main wall for cooperating with said tongue of said closure plate in correspondence with the operative location of said closure plate for fixing said container on said platform jointly to the bearing of said sensing elements against said coils.

2. In an inked ribbon cartridge including a parallelepipedal container having top and bottom walls interconnected by side walls, a pair of ribbon spools variably winding coils of inked ribbon thereon. said spools being in lateral spaced relation within said container, and means included in said container for rotatably supporting said spools about axes perpendicular to said top and bottom walls, one rear wall of said side walls including a pair of slots for the passage of a portion of said ribbon from the one to another of said spools outside container. and said bottom wall having a pair of openings therethrough concentrically aligned with said ribbon spools for causing a pair of spindle means of a printing calculating machine to engage said pair of spools. the combination comprising a. a pair of arm members projecting from said rear wall adjacent to said pair of slots for guiding said portion of ribbon parallel to said rear wall a predetermined distance from said rear wall along a line of said printing calculating machine. said spindle means being supported by a platform fixed to said printing calculating machine, and said arm members and said ribbon defining a space accomodat ing a printing head of said calculating machine in correspondence with movement of said printing head along said printing line:

b. means defining apertures in a front wall of said side walls opposite to said rear wall for freely receiving two sensing levers of a ribbon reversal feed mechanism pivoted on said platform of said printing calculating machine, said two spools being accessible by said sensing levers through said apertures to be sensed for a predetermined amount of coil wound thereon to cause said feed mechanism to drive said pair of spindles in one sense and the other sense respectively in dependence on said amount:

c. a pair of covering portions disposed above said spools and included in said top wall for covering said pair of spools; and

d. means defining a supporting surface in said container adjacent to said pair of covering portions and recessed therein for cooperating with a tongue of a closure member pivotally supported by said platform for preventing undesired movement of said container and said ribbon jointly with the sensing of said coils by said sensing levers.

3. A removable cartridge for an inked ribbon ofa calculating machine of the type including a supporting platen. a printing head movable transversely of said platen. a supporting platform transversely stationary with respect to said platen. two motive shafts projecting from said platform and rotatably supported therefrom, a ribbon reversal feed mechanism. two sensing levers fulcrumed on said platform and operatively connected to said feed mechanism for rotating one or another of said two motive shafts in ime predetermined sense of rotation. a closure plate iggluding a central tongue having a detent lug. an engaging tongue having a shoulder a projecting from sai platform, said closure plate being fulcrumed on sai jplatform between an inoperative and an operative tion, resilient means for causing said dentent lug i ff 'said central tongue to engage said shoulder of said eng iging tongue in corresponding with said operative loca 'n of said closure plate and means connecting said c it re plate with said two sensing levers for position said sensing levers from inoperative positions away from said motive shafts in correspondence with said inoperative location of said closure plate to operative positions of said sensing levers near said. motive shafts in correspondence with said operative location of said closure plate, said cartridge comprising:

a. a container including a main wall, a series of side walls connected to said main wall perpendicular to said main wall, two ribbon spools, means rotatably supporting said spools in lateral spaced relation within said container about axes perpendicular to said main wall, and an inked ribbon having ends fixed to said spools and wound in coils in said spools, one side wall of said side walls defining a pair of slits for the passage of a portion of said inked ribbon from the one to the other of said spools outside said container. and said spools being provided with corresponding engaging means for engaging said motive shafts;

b. a pair of arm members projecting from said one side wall for guiding said portion of inked ribbon parallel to said platen and accomodating said printing head along the transverse movement thereof;

c. aperture means in said container for causing said sensing levers in said operative positions to be rotated in response to the amount of coils of inked ribbon wound on said spools;

d. first means defining a recess in said main wall between said axes for cooperating with said central tongue, in correspondence of the operative loca tion of said closure plate, and fixing said container on said platform; and

e. second means defining a space in said one side wall adjacent said recess for accomodating said engaging tongue and said detent lug of said central tongue in the operative location of said closure member, aligning said dentent lug with said one side wall.

4. A removable cartridge for an inked ribbon for an office machine, comprising a container and two ribboncarrying spools rotatable therein in either direction of rotation, said container having at least a main wall to which the axes of said spools are perpendicular. a series of side walls perpendicular to said main wall, a pair of slits in one of said side walls for the passage of the ribbon from the one to the other of said spools along a path which, between the slits, lies outside said container, wherein said machine is of the type including two spindles for engaging said spools, two sensing elements pivoted on said machine, parallel to said axes for sensing the amount of ribbon carried by said spools, a feed reversal mechanism connected to said sensing elements for driving said two spindles in response to the position of said sensing elements, and means for attaching said cartridge to the machine, wherein the improvement comprises: a pair of apertures in a side wall opposite said one side wall, each of said apertures being as sociated with one of said spools, said sensing elements entering said container thru said apertures to sense said amount of ribbon on said spools, and said attaching means comprising a closure member, pivot means supporting said closure member on the machine for movement between a first position in which said closure member holds said cartridge fixed on the machine and a second position in which said cartridge is free to be taken off said machine, and a coupling mechanism arranged on said closure member in order to act on said sensing elements for withdrawing said sensing elements from said apertures when said closure member is in said second position.

5. A removable cartridge according to claim 4, wherein said sensing elements comprise a pair of scissor levers mounted on a pivot on the machine and biased by a spring to rotate in opposite senses, thereby entering the two apertures respectively, said coupling mechanism acting on said levers to rotate said levers against the action of the spring, and said cartridge container having a recess in said opposite wall accommodating said pivot.

6. A removable cartridge according to claim 5, wherein said closure member comprises a tongue, said tongue, in said first position of said closure member, being received within a recess of said main wall of said cartridge container and being swung away from said main wall recess on movement to said second position of said closure member.

7. A removable cartridge according to claim 6, wherein the free end of said tongue remote from said pivot means of said closure member ends in a V-shaped projection. said projection carrying a detent lug for en gaging a shoulder fixed to the machine, thereby holding said closure member releasably in the first position, and said cartridge wall is recessed to accomodate said projection and shoulder.

8. A removable cartridge according to claim 7 to said ribbon slits to guide said ribbon outside said container over a path spaced from said one side wall, said two arms projecting from said one side wall for defining a space between said ribbon and said one side wall, within which a printing head of the machine is mov able. said Vshaped projection and said shoulder being outside the path of movement of said printing head.

9. A inked ribbon feed mechansim for an office ma chine comprising:

a. a cartridge including a container. two spools rotat able in said container, and inked ribbon having one end attached to one of said two spools and the other end attached to the other of said two spools, said ribbon being wound in coils over said spools, two slits in said container for the passage of said inked ribbon from the one to the other of said two spools outside said container and means defining a passage in said container;

b. supporting means for removably supporting said container on said office machine;

c, two spindle means rotatable on said supporting means about parallel axes and engageable by said two spools for respectively rotating said spools in either direction of rotation:

d. two sensing elements movably supported by said supporting means between an inoperative position away from said spools and an operative position wherein said sensing elements bear against said coils of ribbon wound on said spools;

e. a ribbon reversal mechanism operatively connected with said sensing elements when in said operative position for driving one of said two spindle means in a predetermined sense of rotation upon sensing a predetermined amount of said coils being wound on one of said spools;

f, a closure member movably supported by said supporting means between a first position wherein said closure member fixes said container over said supporting means and a second position wherein said closure member releases said container for allowing said container to be taken off said supporting means along a direction parallel to said axis, said passage defining means of said cartridge lying in a path outside said sensing elements positioned in said inoperative position; and

g. a coupling mechanism connecting said closure member with said two sensing elements for causing said sensing elements to be positioned in said inoperative position when said closure member is in said second position, so that said container can be freely taken off.

10. An inked ribbon feed mechanism according to claim 9 wherein said container includes a main wall rotatably supporting said two spools about axes perpendicular to said main wall, a series of side walls perpendicular to said main wall, said two slits being included in said side walls and said two sensing elements being in said inoperative position away from said container 11. An inked ribbon feed mechanism according to claim 9, wherein said supporting means comprise a platform of said machine and said two sensing elements comprise a pair of scissor levers mounted on a pivot fixed to said platform, said pair of scissor levers being biased by a spring to rotate in opposite senses toward said two spools when in said operative positions; and said coupling mechanism acting on said pair of scissor levers to rotate said pair of scissor levers against the ac tion of said spring in said second position of said closure member.

12. An inked ribbon feed mechanism according to claim 9, wherein said closure member includes a T shaped plate having two arms and a central tongue and wherein said supporting means comprise a platform, pivot means of said platform pivotally mounting said two arms of said T shaped plate. and a shoulder pro jecting from said platform, one end of said central tongue of said T shaped plate including a V shaped pro jection and said projection carrying a detent lug for engaging said shoulder in the first position of said closure member, and fixing said container over said platform,

13. An inked ribbon feed mechanism according to claim 9. wherein said ribbon reversal mechanism comprises a reversal member engaging, between a first position and a second position. a corresponding drive element of a ribbon drive mechanism in order to effect drive of said ribbon spools in one sense and the other sense, respectively, a reversal spring and means carrying said reversal spring for causing said reversal spring to bias said reversal member from said first position towards said second position and vice-versa a pair of latches for arresting said reversal member in said first position and in said second position against the action of said reversal spring, each of said pair of latches cooperating with a corresponding one of said two sensing elements in order to disengage said reversal member when the inked ribbon on the corresponding spool has reached a minimum quantity such as to require reversal of the inked ribbon, thereby causing said reversal spring to move said reversal member from said first position to the second position and vice-versa and a reload element responsive to the movement of said reversal member for repositioning said carrying means for causing said reversal spring to bias said reversal member from said second position back towards said first position and vice-versa.

14. An inked ribbon feed mechanism according to claim 13 wherein said ribbon drive mechanism comprises two spool gears coupled to said two spindle means, respectively, and a train of further gears driven by a drive shaft rotatable in a single direction, two oppositely rotating ones of said further gears being parallel to and coaxial with said two spool gears, respectively, and said drive elements including two pinions freely rotatable on said reversal member, said reversal member, in said first position and in said second position causing a corresponding one of said pinions to be meshed with a corresponding one of said spool gears and with the further gear coaxial with said spool gear.

15. A device for fixing a removable cartridge for inked ribbon to an office machine, wherein said cartridge comprises: a container rotatably supporting two ribbon-carrying spools, a cover of said container to which the axes of said spools are perpendicular, a series of side walls perpendicular to said cover, a pair of slits in one of said side walls for the passage of the ribbon from the one to the other of said spools, and a pair of apertures in a side wall opposite the said one side wall, each of said apertures being associated with a corresponding one of said spools, said office machine comprising a reversably feeding ribbon mechanism provided with a pair of sensing elements for sensing the mount of ribbon on said spools, said fixing device comprising a closure member, a coupling mechanism prise a pair of scissor levers biased by a spring for hearing against said ribbon on said two spools, respectively, said cam means being arranged to transmit thrust to said levers, in order to rotate said levers against the action of said spring when the closure member is moved from said first position to said second position.

17. A device according to claim 16, wherein said cam means transmit thrust to said levers through two rocking levers pivotally mounted on the machine.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N 795 Dated June 17, 1975 Inventor) Sergio Garberi, Lorenzo Bertino It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The foreign application priority data should read as follows:

October 21, 1971 Italy 70460-A/71 May 3, 1972 Italy 68360-A/72 Signed and Scaled this Twenty-second Day Of February 1977 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Office Commissioner nflarents and Trademarks

Claims (17)

1. A removable cartridge for an inked ribbon for an office printing machine of the type including a supporting platform, two motive shafts rotatably projecting from said platform, a ribbon reversal feed mechanism including two sensing elements for rotating one or another of said two motive shafts in one predetermined sense of rotation, a closure plate including a central tongue, an engaging tongue projecting from said platform, said closure plate being fulcrumed on said platform between an inoperative location and an operative location for causing said central tongue to engage said engaging tongue in correspondance with said operative location of said closure plate, and means connecting said closure plate with said two sensing elements for moving said sensing elements from inoperative positions away from said motive shafts in correspondence with said inoperative location of said closure plate of operative positions of said sensing elements near said motive shafts, in correspondence with said operative location of said closure plate, said cartridge comprising a. a container including a main wall, a series of side elements connected to said main wall perpendicular to said main wall, two ribbon spools, means rotatably supporting said spools in lateral spaced relation within said container about an axis perpendicular to said main wall, means for accomodating said motive shafts concentrically with said spools, and an inked ribbon having ends fixed to said spools and wound in coils on said spools, one of said side elements defining a pair of slits for the passage of said inked ribbon from the one to the other of said spools outside said container, and said spools being provided with corresponding engaging means for engaging said motive shafts; b. aperture means on said container for causing said sensing elements during the movement thereof from said inoperative positions to said operative positions to bear against said coils of ribbons wound on said spools, and sense the amount of coils of ribbon wound on said spools; and c. first means defining a recess between said two spools in said main wall for cooperating with said tongue of said closure plate in correspondence with the operative location of said closure plate for fixing said Container on said platform jointly to the bearing of said sensing elements against said coils.

2. In an inked ribbon cartridge including a parallel-epipedal container having top and bottom walls interconnected by side walls, a pair of ribbon spools variably winding coils of inked ribbon thereon, said spools being in lateral spaced relation within said container, and means included in said container for rotatably supporting said spools about axes perpendicular to said top and bottom walls, one rear wall of said side walls including a pair of slots for the passage of a portion of said ribbon from the one to another of said spools outside container, and said bottom wall having a pair of openings therethrough concentrically aligned with said ribbon spools for causing a pair of spindle means of a printing calculating machine to engage said pair of spools, the combination comprising a. a pair of arm members projecting from said rear wall adjacent to said pair of slots for guiding said portion of ribbon parallel to said rear wall a predetermined distance from said rear wall along a line of said printing calculating machine, said spindle means being supported by a platform fixed to said printing calculating machine, and said arm members and said ribbon defining a space accomodating a printing head of said calculating machine in correspondence with movement of said printing head along said printing line; b. means defining apertures in a front wall of said side walls opposite to said rear wall for freely receiving two sensing levers of a ribbon reversal feed mechanism pivoted on said platform of said printing calculating machine, said two spools being accessible by said sensing levers through said apertures to be sensed for a predetermined amount of coil wound thereon to cause said feed mechanism to drive said pair of spindles in one sense and the other sense respectively in dependence on said amount; c. a pair of covering portions disposed above said spools and included in said top wall for covering said pair of spools; and d. means defining a supporting surface in said container adjacent to said pair of covering portions and recessed therein for cooperating with a tongue of a closure member pivotally supported by said platform for preventing undesired movement of said container and said ribbon jointly with the sensing of said coils by said sensing levers.

3. A removable cartridge for an inked ribbon of a calculating machine of the type including a supporting platen, a printing head movable transversely of said platen, a supporting platform transversely stationary with respect to said platen, two motive shafts projecting from said platform and rotatably supported therefrom, a ribbon reversal feed mechanism, two sensing levers fulcrumed on said platform and operatively connected to said feed mechanism for rotating one or another of said two motive shafts in one predetermined sense of rotation, a closure plate including a central tongue having a detent lug, an engaging tongue having a shoulder a projecting from said platform, said closure plate being fulcrumed on said platform between an inoperative and an operative location, resilient means for causing said dentent lug of said central tongue to engage said shoulder of said engaging tongue in corresponding with said operative location of said closure plate and means connecting said closure plate with said two sensing levers for position said sensing levers from inoperative positions away from said motive shafts in correspondence with said inoperative location of said closure plate to operative positions of said sensing levers near said, motive shafts in correspondence with said operative location of said closure plate, said cartridge comprising: a. a container including a main wall, a series of side walls connected to said main wall perpendicular to said main wall, two ribbon spools, means rotatably supporting said spools in lateral spaced relation within said container about axes perpendicular to said main wall, and an inked ribbon having ends fixed to said spools and wound in coils in said spools, one side wall of said side walls defining a pair of slits for the passage of a portion of said inked ribbon from the one to the other of said spools outside said container, and said spools being provided with corresponding engaging means for engaging said motive shafts; b. a pair of arm members projecting from said one side wall for guiding said portion of inked ribbon parallel to said platen and accomodating said printing head along the transverse movement thereof; c. aperture means in said container for causing said sensing levers in said operative positions to be rotated in response to the amount of coils of inked ribbon wound on said spools; d. first means defining a recess in said main wall between said axes for cooperating with said central tongue, in correspondence of the operative location of said closure plate, and fixing said container on said platform; and e. second means defining a space in said one side wall adjacent said recess for accomodating said engaging tongue and said detent lug of said central tongue in the operative location of said closure member, aligning said dentent lug with said one side wall.

4. A removable cartridge for an inked ribbon for an office machine, comprising a container and two ribbon-carrying spools rotatable therein in either direction of rotation, said container having at least a main wall to which the axes of said spools are perpendicular, a series of side walls perpendicular to said main wall, a pair of slits in one of said side walls for the passage of the ribbon from the one to the other of said spools along a path which, between the slits, lies outside said container, wherein said machine is of the type including two spindles for engaging said spools, two sensing elements pivoted on said machine, parallel to said axes for sensing the amount of ribbon carried by said spools, a feed reversal mechanism connected to said sensing elements for driving said two spindles in response to the position of said sensing elements, and means for attaching said cartridge to the machine, wherein the improvement comprises: a pair of apertures in a side wall opposite said one side wall, each of said apertures being associated with one of said spools, said sensing elements entering said container thru said apertures to sense said amount of ribbon on said spools, and said attaching means comprising a closure member, pivot means supporting said closure member on the machine for movement between a first position in which said closure member holds said cartridge fixed on the machine and a second position in which said cartridge is free to be taken off said machine, and a coupling mechanism arranged on said closure member in order to act on said sensing elements for withdrawing said sensing elements from said apertures when said closure member is in said second position.

5. A removable cartridge according to claim 4, wherein said sensing elements comprise a pair of scissor levers mounted on a pivot on the machine and biased by a spring to rotate in opposite senses, thereby entering the two apertures respectively, said coupling mechanism acting on said levers to rotate said levers against the action of the spring, and said cartridge container having a recess in said opposite wall accommodating said pivot.

6. A removable cartridge according to claim 5, wherein said closure member comprises a tongue, said tongue, in said first position of said closure member, being received within a recess of said main wall of said cartridge container and being swung away from said main wall recess on movement to said second position of said closure member.

7. A removable cartridge according to claim 6, wherein the free end of said tongue remote from said pivot means of said closure member ends in a V-shaped projection, said projection carrying a detent lug for engaging a shoulder fixed to the machine, thereby holding said closure member releasably in the first position, and said cartridge wall is recessed to accomodate said projection and shoulder.

8. A removable cartridge according to claim 7 to said ribbon slits to guide said ribbon outside said container over a path spaced from said one side wall, said two arms projecting from said one side wall for defining a space between said ribbon and said one side wall, within which a printing head of the machine is movable, said V-shaped projection and said shoulder being outside the path of movement of said printing head.

9. A inked ribbon feed mechansim for an office machine comprising: a. a cartridge including a container, two spools rotatable in said container, and inked ribbon having one end attached to one of said two spools and the other end attached to the other of said two spools, said ribbon being wound in coils over said spools, two slits in said container for the passage of said inked ribbon from the one to the other of said two spools outside said container and means defining a passage in said container; b. supporting means for removably supporting said container on said office machine; c. two spindle means rotatable on said supporting means about parallel axes and engageable by said two spools for respectively rotating said spools in either direction of rotation; d. two sensing elements movably supported by said supporting means between an inoperative position away from said spools and an operative position wherein said sensing elements bear against said coils of ribbon wound on said spools; e. a ribbon reversal mechanism operatively connected with said sensing elements when in said operative position for driving one of said two spindle means in a predetermined sense of rotation upon sensing a predetermined amount of said coils being wound on one of said spools; f. a closure member movably supported by said supporting means between a first position wherein said closure member fixes said container over said supporting means and a second position wherein said closure member releases said container for allowing said container to be taken off said supporting means along a direction parallel to said axis, said passage defining means of said cartridge lying in a path outside said sensing elements positioned in said inoperative position; and g. a coupling mechanism connecting said closure member with said two sensing elements for causing said sensing elements to be positioned in said inoperative position when said closure member is in said second position, so that said container can be freely taken off.

10. An inked ribbon feed mechanism according to claim 9 wherein said container includes a main wall rotatably supporting said two spools about axes perpendicular to said main wall, a series of side walls perpendicular to said main wall, said two slits being included in said side walls and said two sensing elements being in said inoperative position away from said container.

11. An inked ribbon feed mechanism according to claim 9, wherein said supporting means comprise a platform of said machine and said two sensing elements comprise a pair of scissor levers mounted on a pivot fixed to said platform, said pair of scissor levers being biased by a spring to rotate in opposite senses toward said two spools when in said operative positions; and said coupling mechanism acting on said pair of scissor levers to rotate said pair of scissor levers against the action of said spring in said second position of said closure member.

12. An inked ribbon feed mechanism according to claim 9, wherein said closure member includes a T shaped plate having two arms and a central tongue and wherein said supporting means comprise a platform, pivot means of said platform pivotally mounting said two arms of said T shaped plate, and a shoulder projecting from said platform, one end of said central tongue of said T shaped plate including a V shaped projection and said projection carrying a detent lug for engaging said sHoulder in the first position of said closure member, and fixing said container over said platform.

13. An inked ribbon feed mechanism according to claim 9, wherein said ribbon reversal mechanism comprises a reversal member engaging, between a first position and a second position, a corresponding drive element of a ribbon drive mechanism in order to effect drive of said ribbon spools in one sense and the other sense, respectively, a reversal spring and means carrying said reversal spring for causing said reversal spring to bias said reversal member from said first position towards said second position and vice-versa a pair of latches for arresting said reversal member in said first position and in said second position against the action of said reversal spring, each of said pair of latches cooperating with a corresponding one of said two sensing elements in order to disengage said reversal member when the inked ribbon on the corresponding spool has reached a minimum quantity such as to require reversal of the inked ribbon, thereby causing said reversal spring to move said reversal member from said first position to the second position and vice-versa and a reload element responsive to the movement of said reversal member for repositioning said carrying means for causing said reversal spring to bias said reversal member from said second position back towards said first position and vice-versa.

14. An inked ribbon feed mechanism according to claim 13 wherein said ribbon drive mechanism comprises two spool gears coupled to said two spindle means, respectively, and a train of further gears driven by a drive shaft rotatable in a single direction, two oppositely rotating ones of said further gears being parallel to and coaxial with said two spool gears, respectively, and said drive elements including two pinions freely rotatable on said reversal member, said reversal member, in said first position and in said second position causing a corresponding one of said pinions to be meshed with a corresponding one of said spool gears and with the further gear coaxial with said spool gear.

15. A device for fixing a removable cartridge for inked ribbon to an office machine, wherein said cartridge comprises: a container rotatably supporting two ribbon-carrying spools, a cover of said container to which the axes of said spools are perpendicular, a series of side walls perpendicular to said cover, a pair of slits in one of said side walls for the passage of the ribbon from the one to the other of said spools, and a pair of apertures in a side wall opposite the said one side wall, each of said apertures being associated with a corresponding one of said spools, said office machine comprising a reversably feeding ribbon mechanism provided with a pair of sensing elements for sensing the mount of ribbon on said spools, said fixing device comprising a closure member, a coupling mechanism mounted on said closure member cooperating with said sensing elements, and pivot means of said machine pivotally mounting said closure member for movement between a first position wherein said closure member cooperates with said cover for holding said cartridge fixed to said machine and a second position wherein said coupling mechanism withdraws said sensing elements from said apertures.

16. A device according to claim 15, wherein said coupling mechanism comprises: cam means on the closure member and wherein said sensing elements comprise a pair of scissor levers biased by a spring for bearing against said ribbon on said two spools, respectively, said cam means being arranged to transmit thrust to said levers, in order to rotate said levers against the action of said spring when the closure member is moved from said first position to said second position.

17. A device according to claim 16, wherein said cam means transmit thrust to said levers through two rocking levers pivotally mounted on the machine.

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