EP0387197A1 - Reloadable ink ribbon cassette - Google Patents

Abstract

The cassette consists of an adaptor (1), which is permanently inserted in a typewriter, and a reloading unit (20). In a housing (13), the adaptor (1) has a ribbon drive consisting of a drive pin (55) and an arm (2) which can be swivelled about the latter, and on which a drive wheel (53) is mounted rotatably. Additionally, a ribbon tensioning device (12, 11, 15, 54) is accommodated in the adaptor (1). The housing (13) has two projecting limbs (13a) which bear centring pins (7) at their free ends. The reloading unit (20) has a support (21) with two projecting limbs (21a). Held in the support (20) are a winding-off reel (40) and a winding-on core (43). The ink ribbon (42) is guided from the reel (40) via ribbon guide elements (27, 28) to the winding-on core (43). The ribbon guide elements (27) at the free ends of the support limbs are centred on the pins (7). By this design, simple reloading, a high degree of operational reliability, low material expenditure for disposable parts and a low degree of environmental pollution in disposal are achieved. <IMAGE>

Description

A reloadable ribbon cassette is known from DE-OS 35 24 730. It is a cassette with a hinged lid. An unwinder with an unwinder core is contained in the cassette housing. The unwinding core is seated on a sleeve of a rotatable brake disc. A belt tensioning device interacts with the brake disc. The tape is guided from the unwinding reel via the tape tensioning device and tape guide members at the free ends of two protruding legs of the housing to a winding core. This is rotatably mounted on a spring-loaded swivel arm. The swivel arm presses the winding core against a spiked wheel mounted on the housing with a drive pin for engaging a drive element of the typewriter. To insert a new ribbon, the cassette is first removed from the typewriter. The swivel arm with the take-up spool is swiveled away from the sprocket by means of a lever. Now the full take-up reel with the take-up core and the empty take-up core can be removed. The new unwinding spool is placed on the brake disc and a new winding core on the swivel arm attached. The beginning of the tape can then be threaded over the tape guide elements. For this purpose, a pin with a predetermined breaking point is attached to the beginning of the tape. The lower part of the pin is finally inserted into a slot in the winding core and the rest of the pin is broken off. After closing the lid, the reloaded cassette can be reinserted into the typewriter. The reloading process described is cumbersome and complicated, so that it sometimes fails. The cartridge must be removed from the typewriter for reloading. In addition, when the lever is locked and the associated pivoting movement of the winding core against the sprocket wheel, the tape becomes loose, so that the first windings of the winding spool are poorly wound. This can lead to malfunctions during further winding.

The object of the present invention is to design a reloadable ink ribbon cassette in accordance with the preamble of claim 1 in such a way that the above disadvantages are avoided. This object is achieved by the characterizing features of claim 1. The reloading unit according to the invention is defined in claim 5.

• Fig. 1 eine Draufsicht auf eine erfindungsgemässe Kassette,
• Fig. 2 und Fig. 3 eine Draufsicht und eine Seitenansicht eines Adapters,
• Fig. 4 eine Nachladeeinheit im versandbereiten Zustand in perspektivischer Darstellung,
• Fig. 5 die Nachladeeinheit nach Fig. 4 vor dem Einsetzen in den Adapter,
• Fig. 6 und Fig. 7 Bestandteile der Nachladeeinheit nach Fig. 4 und 5 in perspektivischer Darstellung,
• Fig. 8 einen Schnitt längs der Linie VIII-VIII in Fig. 1,
• Fig. 9 und Fig. 10 ein zweites Ausführungsbeispiel einer Nachladeeinheit,
• Fig. 11 einen in eine Schreibmaschine integrierten Adapter, und
• Fig. 12 bis Fig. 14 ein drittes Ausführungsbeispiel.

An exemplary embodiment of the invention is explained below with reference to the drawings. It shows:

• 1 is a plan view of a cassette according to the invention,
• 2 and 3 are a plan view and a side view of an adapter,
• 4 a reloading unit in the ready-to-ship state in a perspective view,
• 5 shows the reloading unit according to FIG. 4 before being inserted into the adapter,
• 6 and FIG. 7 components of the reloading unit according to FIGS. 4 and 5 in a perspective view,
• 8 shows a section along the line VIII-VIII in FIG. 1,
• 9 and FIG. 10 a second embodiment of a reloading unit,
• 11 shows an adapter integrated in a typewriter, and
• Fig. 12 to Fig. 14 shows a third embodiment.

1 can be used as a whole as a conventional ribbon cartridge in a typewriter. In contrast to conventional cartridges, it consists of an adapter 1 and a reloading unit 20. The adapter 1 is designed such that it can remain permanently in the typewriter, while the reloading unit 20 is replaced as a disposable item after the ink ribbon has been used up. The essential mechanical parts required for the belt drive and the belt tension are accommodated in the adapter 1. The reloading unit 20 contains only a minimum of individual parts. This training achieves an ecologically and economically optimal solution in that the reloading unit is inexpensive to manufacture and its disposal does little for the environment burdened because it contains no metal parts and can be made from environmentally friendly, disposable materials with little material.

The adapter 1 is shown in Figures 2 and 3. It consists of an open-top housing 13 made of plastic injection molding with a flat base plate 13c and a side wall 13b. The rearmost area of the housing 13 is covered with a narrow cover 14. The housing 13 has two protruding legs 13a. A centering pin 7 projects from the base plate 13c at each of its free ends. Another centering pin 8 is arranged in the attachment end of the right leg 13a. A plurality of spacer webs 10 for supporting the reloading unit 20 and two hollow mandrels 3, 4 are integrally formed on the base plate 13c. A brake disc 11 with an integrally formed coaxial sleeve 11a is rotatably and captively attached to the mandrel 3. The sleeve 11a has a plurality of drivers 11b on its outer circumference. The brake disc 11 is toothed on its outer circumference. A clamping element 12 designed as a double-armed lever is pivotably mounted on a housing-fixed pin 12a adjacent to a corner of the housing 13. The first arm of the element 12 has latches 19 at the free end, which are pressed by a spring 15 for engagement in the toothing of the brake disc 11. The other arm of the element 12 carries a belt tensioning roller 54 at the free end.

A nose 18 is formed on the first arm. Adjacent to the right rear corner of the housing 13, a drive pin 55 is rotatably mounted in the housing 13 with, for example, a cruciform through opening for the engagement of a drive shaft of the typewriter. An arm 2 is pivotable on the pin 55. This carries a drive wheel 53 designed as a spiked wheel, which is non-rotatably connected to the drive pin 55 via toothed intermediate wheels 56. At the free end, the arm 2 has a finger 17 which interacts with the nose 18. The arm 2 is prestressed by a spring 16, so that during operation the drive wheel 53 is pressed against a take-up spool 43a placed on the mandrel 4. The arm 2 has a control cam 52. A double-armed, double-cranked actuating lever 6 is snapped with a cylindrical middle part into a bearing 5 formed on the side wall 13b. When the lever 6 is pivoted out in the direction of arrow A, a lever arm 51 of the lever 6 runs on the control cam 52 and pivots the arm 2 against the force of the spring 16 into the loading position shown in FIG. 2. In this position, the lever arm 51 engages in a notch 52a of the control cam 52. In the loading position, the finger 17 pivots the element 12 clockwise over the nose 18, so that the tensioning roller 54 is pivoted away from its operating position in the direction of arrow B. The latches 19 also disengage from the toothing of the brake disk 11.

According to FIGS. 6 and 7, the reloading unit 20 comprises a thin-walled carrier 21 injection-molded from plastic with two projecting carrier legs 21a and a circumferential side wall 21b. The side wall 21b is interrupted at the free leg ends and at the right rear edge of the carrier 21. Hollow pins 27 are formed on the free leg ends as band guide members. At the top, the hollow pins 27 carry a retaining collar 27b for the ink ribbon 42. Two further ribbon guide members 28 are arranged adjacent to two hollow pins 23, 24. The hollow pins 23, 24 each have two latching lugs 25 at their free ends. An unwinding core 41 with an unwinding spool 40 is attached to the hollow pin 23 and held captively by the lugs 25. In the same way, a winding core 43 is attached to the other hollow pin 24. The ink ribbon 42 is guided from the unwind spool 40 via the ribbon guide members 27, 28 to the winding core 43 and fastened thereon. On the left carrier leg 21a there is an opening 30 through which the tensioning roller 54 projects during operation. Another opening 31 on the right rear edge of the carrier 21 serves for the entry of the arm 2 with the drive wheel 53. In both legs 21a, an elongated hole is recessed as a locking recess 29 for engaging the locking lugs 9. Grip tabs 33 are formed on the side wall 21b adjacent to the free leg ends, so that the recharging unit 20 can be easily removed from the adapter 1.

The carrier 21 with the unwinding spool 40 and the winding core 43 is inserted into a cardboard box 34 (FIGS. 4 and 5). For centering in the box 34, the side wall 21b of the carrier 21 has two guide elements 32 on each side. The box 34 can be separated into a first part 35a and a second part 35b by a circumferential tear tape 36. The first part 35a encloses the area of the carrier 21 with the unwinding spool 40 and the winding core 43. It has two circular cutouts 39 on the top, through which the winding core 43 and the unwinding core 41 are inserted. Both cores 41, 43 engage behind the cutouts 39 with locking lugs 44 (FIG. 8). On the underside, the part 35a has round openings 39a coaxial with the cutouts 39 for inserting the sleeves 11a and the mandrel 4. At the rear right edge, a piece 37 can be separated from the part 35a by a perforation to expose the opening 31. Radially to the unwinding core 41 an elongated hole 46 extends on the upper side of part 35a as a tape supply indicator. The second part 35b encloses the two legs 21a. This part 35b is removed before use. A cardboard plate 38 is fastened to the inner surface of its upper side as a transport lock. In the shipping state, the free end of the plate 38 is inserted between the take-up spool 40 and the top of the part 35a, so that the unwinding spool 40 is locked without play between the underside of the part 35a and the plate 38. The plate 38 covers the longitudinal slot 46 and is removed together with the part 35b before use. This makes the game necessary for free spinning the unwind spool 40. As a further transport lock, a pawl 26 is integrally formed on the hollow pin 23, which engages in driving claws 41a of the unwinding core 41 and prevents the unwinding spool 40 from rotating counterclockwise.

When the tape supply is used up when writing on the typewriter with the cassette according to the invention, the actuating lever 6 is pivoted into the loading position according to FIG. 2 with the adapter inserted in the typewriter and the used reloading unit 20 is removed. In the case of a new reloading unit 20, the tear tape 36 is torn off and the part 35b with the plate 38 is removed. The piece 37 is cut off. Now the rear side of the part 35a is inserted under the cover 14 and the hollow pin 27, 28 is placed on the centering pins 7, 8. The locking recesses 29 snap into the locking lugs 9 by pressing on the grip tabs 33. In the loading position, the band tensioning element 12 is pivoted such that the band tensioning roller 54 in the illustration according to FIG. 1 is to the right of the band 42 tensioned in the left carrier leg 21a between the band guide members 27, 28 (shown in dashed lines in FIG. 1). When inserted, the sleeve 11a engages with its drivers 11b in the unwinding core 41 with its driver claws 41a and at the same time moves the pawl 26 out of engagement with these claws 41a. The winding core 43 is centered on the mandrel 4. The underside of the box part 35a lies on the spacer webs 10. Finally, the operating lever 6 from the drawer shown in Fig. 2 1, the lever 2 presses the drive wheel 53 against the winding core 43, and the belt tensioning roller 54 pivots into the position shown in solid lines in FIG. 1, in which it is partially wrapped by the belt 42. The latches 19 come into engagement with the toothing of the brake disk 11.

In operation, the drive pin 55 is gradually rotated by the typewriter after each stop. This rotation is transmitted via the intermediate wheels 56 to the drive wheel 53, which thus rotates the take-up spool 43a in the counterclockwise direction and pulls the ink ribbon 42 off via the ribbon guide members 27, 28. When the band tension increases, a force acts on the band tensioning roller 54, which swivels the band tensioning element 12 clockwise until the latches 19 disengage from the toothing of the brake disc 11 and thus the unwinding spool 40 can rotate one tooth further. A constant, elastic band tension is maintained by the spring 15 and the band tensioning element 12.

The described design of the cassette enables simple reloading analogous to the replacement of conventional cassettes, the adapter 1 being able to remain permanently in the typewriter. No cumbersome threading of the new ribbon is required. The ribbon is tensioned after insertion so that the take-up spool is tightly wound from the start. This can cause malfunctions be avoided. The carrier 21 and the cores 41, 43 can be made very light and made of the same material as the ink ribbon. As a result, the cost of materials and the environmental impact are low, especially when this consumable is recycled. The cardboard box 34 serves both as transport packaging and as a cover during operation.

The embodiment according to FIGS. 9 and 10 of the reloading unit 20 'is designed for use in the same adapter 1 according to FIGS. 2 and 3. The reloading unit 20 'in turn consists of a carrier 21', an unwinding core 41 with an unwinding spool 40, a winding core 43 and a cardboard sleeve 60. The carrier 21 'differs from the carrier 21 according to FIG. 7 only in that two hook-shaped latching springs 61, 62 protrude upward from the side wall 21b adjacent to the central plane. The casing 60 differs from the box part 53a according to FIGS. 4 and 5 (with the piece 37 cut off) only in that it still has two rectangular openings 63, 64 through which the detent springs 61, 62 protrude. In the reloading unit 20 'according to FIGS. 9 and 10, however, the transport lock is fundamentally different from the embodiment according to FIGS. 4 to 8. It here consists of a cardboard slide 65 arranged on the upper outside of the casing 60. The slider 65 has approximately the same width as the sleeve 60, but is somewhat shorter than that. It has two keyhole-like slots 66, 67 through which the Lugs 44 of the cores 41, 43 protrude. The holes 66, 67 have two circular segment-shaped edge sections 68, 69. The section 68 has a diameter which is larger than the outside diameter of the locking lugs 44. The diameter of the section 69, on the other hand, is somewhat smaller than the diameter of the cutouts 39 according to FIGS. 4 and 8. The front and rear of the slide 65 each have a cutout 70, 71 with an outer edge 73 parallel to the longitudinal edges 72 of the slide 65. A detent 74 projects from the edge 73. The edge 73 is encompassed by the hook-shaped springs 61, 62. The slide 65 additionally has two grip notches 75, 76, by means of which it can be moved from the locked position shown in FIG. 9 into the release position according to FIG. 10. In both positions, the slider 65 is secured behind the detents 74 by latching the detent springs 61, 62. In the locked position (FIG. 9), the cores 41, 43 are clamped through the sections 69 of the holes 66, 67 and thus secured against rotation. At the same time, the axial play between the spool 40 and the upper box wall is canceled in an analogous manner, as shown in FIG. 8, except that the upper box wall lies directly on the spool body here. In the release position (FIG. 10) the clamping of the cores 41, 43 is released and the upper box wall lifts off the coil body. In the release position, a longitudinal slot 77 of the slide 65 is aligned with the elongated hole 46 in the box 60, so that the tape supply indicator is visible. In order to visually lift the blocking position from the release position, the top of the chess tel on the right edge 78 green, on the left edge 79 colored red, or the edges 78, 79 can be labeled accordingly. The hole 66 expediently has a projection 69a on its edge section 69, which engages in the locked position in the core 41 and additionally secures the unwinding spool 40.

The embodiment according to FIGS. 9 and 10 has above all the advantage over that according to FIGS. 4 to 8 that the unwinding spool is secured until after insertion. In addition, the reloading unit 20 'can also be taken in between, before the end of the tape supply on the spool 40, from the adapter 1 and replaced by another reloading unit 20' with a different tape quality. This is desirable, for example, if the same typewriter alternately writes document-correct (uncorrectable) fonts and correctable ribbons are used. In such cases, in the unit 20 'to be replaced, the slide 65 is first pushed into the locked position (FIG. 9) and then the exchange unit 20' is removed from the adapter 1. The winding and unwinding spools are then secured against twisting during handling.

FIG. 11 schematically shows a variant in which the adapter 1 according to FIG. 2 forms part of a typewriter 85. The two housing legs 13a then protrude on both sides of the character printing device, for example one Type wheel 86, against the platen roller 87 in front. The centering pins 7 are immediately adjacent to the platen roller 87. The housing 13 is expediently pivoted in the typewriter 85 about an axis 88 parallel to the platen roller 87, so that during operation the ink ribbon 42 stretched between the ribbon guide members 27, which is between the platen roller 87 and the type wheel 86 is carried out, can be pivoted between a raised writing position and a lowered reading position. 11, parts that are not mentioned here are omitted from the typewriter 85 for better clarity.

12 to 14 show a further embodiment of the invention, the same reference numerals being used for analog parts as in the embodiment according to FIGS. 1 to 8, so that a detailed description of these parts is unnecessary. The embodiment of FIGS. 12 to 14 differs from that of FIGS. 1 to 8 essentially only by the type of centering of the legs 21a˝ of the carrier 21˝ on the legs 13a 'of the adapter 1' and by the function of the tape guide members 27th ˝. Otherwise, the adapter 1 'and reloading unit 20˝ are constructed in the same way as in the embodiment according to FIGS. 1 to 8, so that the parts which are not connected to the belt guide and centering are omitted or are only indicated schematically in a simplified manner.

The centering members 7 'of the housing legs 13a' are here semi-cylindrical, perpendicular from the housing legs 13a 'projecting bolts 90, which are closed at the top by a flange 91 projecting in the direction of the free leg ends. Accordingly, the centering elements 27b˝ adjacent to the free end of the carrier legs 21a˝ are designed as semi-cylindrical shells 92. Starting from the shells 92, the support legs 21a˝ each have an elongated hole 93 through which the relevant pin 90 can be inserted. The tape guide member 27˝ is formed by an end edge 94 of an extension 95 of the side wall 21b˝ of the carrier 21˝. For the sake of a better overview, the band 42 is drawn in dashed lines. The front edge 94 is delimited at the top by a protrusion 96 so that the band 42 cannot slide upwards.

The embodiment according to FIG. 12 is suitable for use in a typewriter which, in operation, has machine-side tape guide members 97, which are shown schematically in FIGS. 13 and 14 adjacent to the platen roller 87 '. The outside distance of the two band guide members 97 is slightly less than the inside distance of the extensions 95 from one another. To insert the reloading unit 20, the band 42 is first inserted by means of the extensions 95 between the organs 97 and the platen roller 87 'and the carrier legs 21a˝ with their elongated holes 93 on the bolts 90th plugged in, the recharging unit 20 'to the adapter 1' is inclined (arrow A in Fig. 13). Now the reloading unit is pulled back in the direction of arrow B until the shells 92 engage positively around the bolts 90. Finally, the adapter 20˝ is pivoted in the direction of arrow C, so that the unwinding core 41˝ is pushed onto the sleeve 11a˝. In this position the typewriter is ready for operation (Fig. 14). The relatively soft support legs 21a˝ are in turn precisely centered by the rigid bolts 90. The flanges 91 overlap the shells 92 so that the reloading unit 20 'is held securely on the adapter 1'.

The type of centering shown on the basis of the embodiment according to FIGS. 12 to 14 can also be used in typewriters that have no machine-side tape guide members 97. In this case, the elongated holes 93 can be made correspondingly shorter.

Claims (13)

1. Reloadable ink ribbon cassette comprising a housing (13) with two projecting housing legs (13a), each carrying a ribbon guide member (27) for guiding the ink ribbon (42) stretched between the two housing legs (13a), and one with a drive pin (55) Connected drive wheel (53) for pulling the ribbon (42) over the ribbon guide members (27) from a ribbon supply (40), characterized in that the housing (13) is open on its top, that the drive wheel (53) on a spring-loaded arm (2) is rotatably mounted, which is pivotable about the axis of the drive pin (55), that the tape supply (40) is arranged in an exchangeable carrier (21) which is locked in the housing (13), that the tape guide members (27) are integrally formed on the free ends of two support legs (21a) projecting from the support (21), and that the free ends of the support legs (21a) each have a centering element (27b), each on a centering member (7) on the free End of the housing leg (13a) is centered. 2. Cassette according to claim 1, characterized in that the tape supply is designed as a winding spool (40) wound on a winding core (41), that the winding core (41) on a first hollow pin (23) of the carrier (21) is rotatable and captive it is snapped in that on a second hollow pin (24) of the carrier (21) a winding core (43) is snapped rotatably and captively, to which the end of the ink ribbon (42) is attached, that a brake disk on a first mandrel (3) fixed to the housing (11) with a molded sleeve (11a) is rotatably mounted, on which the unwinding core (41) is centered and with which it is connected in a rotationally fixed manner, that the brake disc (11) interacts with a band tensioning element (12) that on a second mandrel fixed to the housing (24) the winding core (43) is centered, and that the drive wheel (53) is pressed against the winding core (43) by the spring (16) of the arm (2). 3. Cassette according to claim 2, characterized in that the arm (2) is pivotable by a manually adjustable actuating element (6) from its operating position into a loading position in which the drive wheel (53) is lifted from the winding core (43), and that the arm (2) is held in the loading position by a latching element (52a). 4. Cassette according to one of claims 1 to 3, characterized in that the centering member (7 ') at its end facing away from the base of the housing (13') has a projection (91) directed towards the free end of the housing leg (13a '). has, which overlaps the centering element (27b˝). 5. Reloading unit for an ink ribbon cassette according to one of claims 1 to 4, comprising a tape supply (40), characterized in that the tape supply (40) is arranged in a carrier (21), the latching members (29) for latching in a housing ( 13) as well as two support legs (21a) projecting from the support (21), at the free end of each one a tape guide member (27) and one centering element (27b) for centering on centering members at the free ends of two housing legs (13) projecting from the housing (13) 13a) is arranged, the ink ribbon (42) being stretched between the ribbon guide members (27). 6. Reloading unit according to claim 5, characterized in that the tape supply is designed as an unwinding spool (40) wound on an unwinding core (41), that the unwinding core (41) is rotatable on a first hollow pin (23) formed on the carrier (21) and is snapped captively, and that on a second hollow pin (24) formed on the carrier (21) a winding core (43) is snapped rotatably and captively, to which the end of the ink ribbon (42) is fastened. 7. Reloading unit according to claim 6, characterized in that the band guide members (27) are further hollow pins for centering on centering pins (7) at the free ends of the housing legs (13a) which protrude from the plate-shaped carrier (21) and at their free end have a retaining collar (27a) for the ink ribbon (42): 8. Reloading unit according to claim 6, characterized in that the band guide members (27˝) by end faces (94) of extensions (95) of a side wall (21a˝) of the carrier (21˝) are formed by the centering elements (27b˝) Form-locking members (92) projecting perpendicularly from the support (21˝) for positive engagement with corresponding counter-members (90) on the adapter (1 ′) are formed, and that recesses (93) are recessed in the support (21˝) starting from the form-locking members (92) are for pushing through the counter links (90). 9. Reloading unit according to one of claims 6 to 8, characterized in that the carrier (21) in the region of the unwinding spool (40) and the winding core (43) is covered by a cover element (35a, 60), and that the winding core (43 ) and the unwinding core (41) with its ends facing away from the carrier (21) are carried out through cutouts (39) in the cover element (35a, 60) and have detents (44) projecting radially outwards at their free end. 10. Reloading unit according to claim 9, characterized in that the cover element (35a, 60) is designed as a shell. 11. Reloading unit according to claim 9 or 10, characterized in that a slide (65) is displaceable between a blocking position and a release position over the top of the cover element (60), that the slide has two elongated holes (66,67) through which the Lugs (44) protrude, and that the width of the elongated holes (66,67) is smaller at one end and larger at the other end than the outside diameter of the lugs (44). 12. Reloading unit according to claim 10, characterized in that the cover (35a) is connected via a tear tape (36) to a further cover part (35b) enclosing the legs (21a) of the carrier (21). 13. Typewriter for using a reloading unit according to one of claims 6 to 12, with a platen roller (87) and a character printing device (86) adjacent to the platen roller (87), characterized in that the machine (85) has an upwardly open housing (13 ) with two projecting housing legs (13a) arranged on both sides of the character printing device (86), each of which has a free end adjacent to the platen roller Centering member (7) for centering the centering elements (27b) of the carrier (21) of the reloading unit (20), that a drive wheel (53) is rotatably mounted on a spring-loaded arm (2), which is about the axis of one with the drive wheel (53 ) connected drive pin (55) that a brake disc with a sleeve (11a) is rotatably mounted on a first mandrel (3) fixed to the housing for centering an unwinding core (41) of the reloading unit (20) that the brake disc (11) with a Band tensioning element (12) cooperates so that a second mandrel (24) for centering a winding core (43) of the reloading unit (20) is arranged in the housing (13), that the drive wheel (53) by the spring (16) of the arm (2) It is preloaded against the second mandrel that the arm (2) can be pivoted from its operating position into a loading position by a manually adjustable actuating element (6), in which the drive wheel (53) is at a distance from the mandrel (24), and that the arm ( 2) in the loading position ng is held by a locking element (52a).

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