Extension guide

Description

The invention relates to an extension guide for mounting a movable furniture part linearly movably along an extension direction, comprising a carcass rail which can be fixed to a furniture carcass, a drawer rail which can be fixed to the movable furniture part, a linearly movable center rail arranged between the carcass rail and the drawer rail, at least one load-transmitting outer carriage arranged between the center rail and the drawer rail, and a synchronizing device.

Extension guides of the type mentioned above may be used for the mounting of a movable furniture part, for example a drawer, to a furniture carcass, for example a cabinet. The drawer may thus be fixed to the drawer rail and the carcass rail may be fixed to the cabinet. To enable opening and closing of the drawer, relative movement between the cabinet and the drawer may be enabled by the extension guide. That is, the drawer may be linearly movable along an extension direction, in order to allow for opening the drawer by extending it and for closing the drawer by retracting it. For this purpose, the drawer rail may be mounted in a linearly movable manner relative to the carcass rail.

A linearly movable center rail arranged between the carcass rail and the drawer rail may help to expand the way that the drawer can be pulled out. For example, it may be desirable that the drawer can be pulled out completely so that the entire interior of the drawer becomes accessible.

Relative movement between the drawer rail and the center rail may be facilitated by an outer carriage. The outer carriage may comprise suitable means to enable the relative movement, for example rollers that may roll in between the drawer rail and the center rail. The outer carriage may be linearly movable in the extension direction. The outer carriage may thus guide the drawer rail on the center rail and further transmit a load from the drawer, for example a weight of the drawer and/or the contents of the drawer, to the center rail.

The center rail may be movable relative to the carcass rail. To facilitate movement of the center rail relative to the carcass rail, suitable means, for example rollers, may be provided between the center rail and the carcass rail. These means may thus guide the center rail on the carcass rail and further transmit a load from the center rail, for example a load transmitted from the drawer rail to the carcass rail. For this purpose, an extension guide according to the invention may comprise at least one load-transmitting inner carriage arranged between the carcass rail and the center rail. The inner carriage may be linearly movable in the extension direction.

To achieve a reproducible, even movement of the rails relative to each other, a synchronizing device may be provided that may enable synchronizing, i.e., defining the position and/or speed relations between individual, several or all rails and/or carriages of the extension guide.

Extension guides may be provided on opposing lateral sides of the drawer relative to the extension direction. Extension guides on opposing sides may be designed in a mirror-inverted way to one another.

An extension guide of the type mentioned in the beginning is known from EP 2 538 818 B1. The extension guide comprises a carcass rail, a center rail and a first carriage arranged in between. The extension guide further comprises a drawer rail and a second carriage arranged in between the center rail and the drawer rail. Further, a synchronizing device is provided that is effective between the first carriage and the drawer rail. The synchronizing device comprises two pinions that are rotationally fixed to one another and that are rotatably mounted on the center rail. The first pinion meshes with a rack disposed at the first carriage and the second pinion meshes with a rack disposed at the drawer rail. The first carriage further comprises rollers mounted rotatably about a vertical axis for lateral guidance of the center rail on the carcass rail.

Even if an extension guide is provided with a synchronizing device, the rails and/or carriages of the extension guide that are not directly synchronized by the synchronizing device may eventually deviate from their defined position. This may, on the one hand, obviously be undesirable.

On the other hand, however, allowing a component to deviate from its defined position may be useful in some circumstances to protect the extension guide from excessive wear or even failure. For example, a user may pull out or push in the drawer very energetically. Or, as another example, a user may accidentally bump into a drawer that is in its open state. In both cases, there will be high forces acting on the extension guide, mainly in or opposed to the extension direction. Such forces may at least partially be dissipated by components of the extension guide that are able to yield to a certain degree. For example, sliding of a carriage between two rails may allow movement of one rail of the extension guide relative to another rail. That is, the sliding may dissipate the impact to some degree. Obviously, this cannot be achieved between two rails that are connected to one another by the synchronizing device.

In the extension guides known in the art, where the synchronizing device is effective between the inner carriage and the drawer rail, following the way of the force of the impact, the synchronizing device will be faced with the whole force of the impact, as it is directly connected to the drawer rail. The first component to be able to yield will be the inner carriage that may slide on the carcass rail. This means that the impact will directly act on the synchronizing device which may comprise mechanically rather delicate parts and may thus wear out or even fail prematurely.

The technical problem to be solved by the invention is to provide an extension guide with improved wear resistance.

This task is solved in that the synchronizing device is effective between the carcass rail and the outer carriage.

In this way, the drawer rail does not need to be directly coupled to the synchronizing device. In a situation as described above, where extreme forces may act on the extension guide in the extension direction, the drawer rail may thus yield to some extent by sliding on the outer carriage. This means that the synchronizing device is protected from an impact that may act on the movable furniture part. This allows the synchronizing device to be better protected from premature wear and, in the worst case, mechanical failure.

Further, the carcass rail may be regarded as a preferred reference basis for synchronization. In contrast to the other rails and the carriage(s) of the extension guide, the carcass rail may be stationarily fixed to the cabinet. An extension guide according to the invention may thus provide enhanced synchronization capabilities because the synchronizing device has a fixed stationary basis.

A reliable and accurate synchronization may be achieved with a compact design if it is provided that the synchronizing device comprises at least a first running surface and a second running surface, that at least one synchronizing wheel rolls on at least one of the running surfaces, and that the first running surface is connected to the carcass rail indirectly or directly in a stationary manner. A direct connection may in this context mean that the first running surface is integrally connected to the carcass rail. For instance, carcass rail and first running surface may be formed as an integral part. An indirect connection may mean that the first running surface is designed as a separate part or as a component of a separate part, which separate part may be connected to the carcass rail.

The synchronizing device being effective between the carcass rail and the outer carriage may be achieved in an advantageous manner if it is further provided that the second running surface is connected directly or indirectly to the outer carriage. A direct connection may in this context mean that the first second running surface is integrally connected to the carcass rail. For instance, the outer carriage and the second running surface may be formed as an integral part. An indirect connection may mean that the second running surface is designed as a separate part or as a component of a separate part, which separate part may be connected to the outer carriage.

If it is provided that the at least one synchronizing wheel is rotatably mounted on the center rail, the center rail may also be synchronized by the synchronizing device. Further, the center rail may be designed as a mechanically sturdy component and thus provide a reliable mounting base for the at least one synchronizing wheel.

Preferably, the at least one synchronizing wheel is rotatable about an axis perpendicular to the extension direction, in particular about a horizontal axis. The direction of rolling of the at least one synchronizing wheel may in this case be aligned with the extension direction.

According to a preferred embodiment of the invention, it may be provided that the first running surface and/or the second running surface is/are designed to be toothed, in particular is/are designed as a rack, and in that the at least one synchronizing wheel is designed as a pinion. A synchronizing wheel may thus mesh with a corresponding running surface. A rack and pinion design of a running surface and a synchronizing wheel that is running on the running surface enables both an accurate synchronization and a reliable transmission of forces, particularly forces acting in the extension direction, between the running surface and the synchronizing wheel.

If a first synchronizing wheel and a second synchronizing wheel are provided, the first synchronizing wheel rolls on the first running surface, and the second synchronizing wheel rolls on the second running surface, the position and/or speed relations between individual, several or all rails and/or carriages of the extension guide may be set by appropriate design of the first synchronizing wheel and the second synchronizing wheel, for example by the choice of appropriate diameters of the first synchronizing wheel and the second synchronizing wheel. In other words, a transmission ratio of the synchronizing device may be chosen as desired for the application.

In this context, a mechanically robust and kinematically simple transmission may be achieved if the synchronizing wheels are connected to one another in a rotationally fixed manner.

The synchronizing wheels may be comfortably and securely connected to one another during assembly if it is provided that the second synchronizing wheel has a head portion and a shaft portion, the first synchronizing wheel having a hub, that the hub is designed to correspond to the shaft portion at least partially, and that the synchronizing wheels are connected to one another in a rotationally fixed manner by means of an at least partial accommodation of the shaft portion in the hub.

In the alternative, it may be provided that the first synchronizing wheel has a head portion and a shaft portion, the second synchronizing wheel having a hub.

Reliable transmission of torque between the synchronizing wheels and a defined angular positioning of the synchronizing wheels relative to each other may be achieved if the shaft portion is provided, at least in regions, with a spline, if the hub is provided, at least in regions, with a mating spline corresponding at least partially to the spline, and if by means of the spline and the mating spline a torque can be transmitted between the second synchronizing wheel and the first synchronizing wheel, preferably in a positive-locking manner.

A robust mounting of the synchronizing wheels may be achieved if it is provided that the shaft portion is guided through a shaft opening in a wall of the center rail.

In this context, if it is further provided that the first synchronizing wheel and the second synchronizing wheel are arranged on opposite sides of the wall, a compact design of the synchronizing device may be achieved. For instance, the center rail may comprise vertical first and second side walls that may be connected by a horizontal top wall, forming an inside space between the walls. The synchronizing wheels may, in this case, preferably be arranged on opposite sides of a side wall. Further, the top wall may be provided with a synchronizing wheel breakthrough, that may be an opening in the top wall, so that the synchronizing wheel located on the inside may partially extend through the synchronizing wheel breakthrough, which may provide a space saving design.

Comfortable and secure mounting as well as good rotatability of the synchronizing wheels may be achieved in that the first synchronizing wheel and the second synchronizing wheel are detachably mounted on the center rail by means of a synchronizing wheel holder, in that the synchronizing wheel holder has a receiving space in which the first synchronizing wheel is partially received, in that the synchronizing wheel holder has a bearing portion through which the shaft portion is guided, and in that in the receiving space, opposite the bearing portion with respect to the first synchronizing wheel, a bearing receptacle is provided in which a bearing projection of the shaft portion is rotatably received.

If it is further provided that that the synchronizing wheel holder has a holding projection, the holding projection preferably being designed as a tongue, that the center rail has a retaining means, the retaining means preferably being of hook-shaped design, that the holding projection is held between the retaining means and a wall of the center rail, that the synchronizing wheel holder further comprises a holding lug which is preferably hook-shaped, and that the holding lug is held at a latching aperture of the center rail, wherein the holding lug preferably penetrates the latching aperture to establish a latching connection, the synchronizing wheel holder may be comfortably and securely attached to the center rail during assembly.

According to a preferred embodiment of the invention, it may be provided that the ratio of a diameter of the first synchronizing wheel to a diameter of the second synchronizing wheel is greater than or equal to 1, preferably greater than or equal to 1.5, particularly preferably is 2.

During retraction or extension of the extension guide, that is, during pulling-out or pushing-in of the movable furniture part, the drawer rail, the outer carriage, the center rail and/or the inner carriage may move in/against the extension direction at a respective speeds relative to the carcass rail.

Assuming that the synchronizing wheels are mounted on the center rail, that the second running surface is connected to the outer carriage and that an inner carriage is provided between carcass rail and center rail, if the above-mentioned ratio of diameters is chosen to be 1, the speed relation between carcass rail, inner carriage, center rail, outer carriage and drawer rail may be 0, 1/6, 1/3, 2/3, 1 (speed of drawer rail assumed to be 1). If the ratio is chosen to be 2, the relation may be 0, 1/4, 1/2, 3/4, 1, which may be a preferred relation because it provides an even distribution of speeds and travel length of the rails and carriages of the extension guide during extension and retraction.

In this context, if the synchronizing wheels are designed as pinions, the ratio of numbers of teeth provided on the synchronizing wheels may correspond to the ratio of diameters. For example, the first synchronizing wheel may be provided with twelve teeth and the second synchronizing wheel may be provided with six teeth.

Conceivably, if the aforementioned assumption is not met, for example if the synchronizing wheels are mounted not on the center rail but on another rail or a carriage, speed relations may differ from those mentioned. In any case, however, the ratio of a diameter of the first synchronizing wheel to a diameter of the second synchronizing wheel may be designed in a manner to achieve advantageous speed and travel relations between parts of the extension guide.

According to an advantageous further development of the invention, it is proposed that an attaching element connected preferably detachably to the carcass rail is provided, and in that the first running surface is provided at least in regions on the attaching element, in particular that the first running surface is designed in one piece with the attaching element in regions. The first running surface may thus be manufactured separately from the carcass rail. This enables the design and manufacture of different types first running surfaces for different applications that may be used with the same type of carcass rail. Further, an attaching element may be replaced, for example if the first running surface is worn, without the need to replace the whole extension guide or the carcass rail.

In this context, the attaching element may further be designed in multiple parts, particularly having at least two attachment segments, on which the first running surface is particularly preferably provided at least in regions. In this way, the same parts may be used for different lengths of carcass rails and/or different lengths of first running surfaces. For example, a longer rail may require a longer first running surface and thus more than one attaching segment may be provided, while for a shorter rail one attaching segment may suffice.

The attaching element may be comfortably and securely mounted to the carcass rail, if it is provided that the attaching element is detachably connected to the carcass rail by means of a latching connection, preferably at least one receiving element being provided on the carcass rail, which receiving element is, in particular, hook-shaped and is received in a receptacle of the attaching element which corresponds at least partially to the receiving element, and wherein further preferably at least one latching projection is provided on the attaching element, which latching projection is received in a positioning receptacle of the carcass rail, which positioning receptacle is designed to correspond at least partially to the latching projection.

According to an advantageous embodiment of the invention it is proposed that first guide means are provided for guiding the center rail and for supporting the center rail transversely to the extension direction, and in that the first guide means are connected to the carcass rail indirectly or directly in a stationary manner. In this context, a stationary connection means that the first guide means do not change their position relative to the carcass rail during an extension or retraction of the movable furniture part. However, a rotation about a stationary axis is considered stationary.

First guide means that are connected to the carcass rail in a stationary manner offer the advantage that they may be spaced freely according to the requirements that the extension guide needs to meet regarding lateral guidance. In particular, they may be spaced independently of the dimensions of an inner carriage that may be provided between the carcass rail and the center rail. Further, according to the invention, the first guide means do not change their position relative to the carcass rail during extension or retraction. This may provide optimum guidance and load transmission between carcass rail and center rail independent of the state of the extension guide (retracted, extended or intermediate state).

In contrast, if the first guide means are provided on a carriage, as according to the prior art, the spacing of the guide means is limited to the length of the carriage that the guide means are mounted on. Further, during extension and extraction of the movable furniture part, the carriage moves relative to the center rail and the carcass rail. This means that, depending on the current state of the extension device (retracted, extended or intermediate state), the ability to transmit lateral loads between the carcass rail and the center rail is variable and thus cannot be optimal in every state.

Particularly high lateral support and guidance requirements may arise if, in addition to the extension guide, a push-out mechanism is provided acting between the furniture carcass and the movable furniture part, for example a drawer. Push-out mechanisms may serve to automatically push out the drawer once an overstroke has been applied to the movable furniture part in the closed state. An overstroke may be induced by a user pushing the closed drawer further in the closing direction. Push-out mechanisms may be provided on both lateral sides of the drawer. It is conceivable that a user may not apply the overtravel to the center of the drawer, or only on one side. In both cases it may be essential that the overstroke applied by the user is transmitted to the push-out mechanism reliably. For example, a user may not always apply the overstroke to the center of the drawer. If the drawer is not guided rigidly enough in the lateral direction, an off-center application of the overstroke may lead to only one of the push-out mechanisms to be triggered, because the necessary travel to trigger the push-out mechanism is not reached on both sides of the drawer. For instance, the drawer may become distorted between its extension guides to some extent. If only one push-out mechanism is provided, an off-center application of the overstroke may not trigger a push-out event at all.

The advantageous embodiment of the invention described above may overcome these problems by providing improved lateral guidance.

If the first guide means are furthermore provided at least in the region of the first running surface in proximity thereto, a compact design is achieved. Preferably, the first guide means may be provided on the/an attaching element which is preferably detachably connected to the carcass rail.

The invention will be explained in more detail below with reference to an example of an embodiment shown in the figures. The figures show:

FIG. 1: a schematic exploded view of an extension guide 1,

FIG. 2: an enlarged view of detail II according to FIG. 1,

FIG. 3: a schematic exploded view of components shown in FIG. 3,

FIG. 4: a schematic view of a center rail 30 combined with a synchronizing device 60,

FIG. 5: a sectional view at location V according to FIG. 4,

FIG. 6: a schematic exploded view of an outer carriage 40,

FIG. 7: a schematic exploded view of an inner carriage 20,

FIG. 8: an enlarged view of detail VIII according to FIG. 7,

FIG. 9: a cropped schematic view of an attaching element 70,

FIG. 10: an enlarged view of detail X according to FIG. 1,

FIG. 11: a schematic side view of an extension guide 1,

FIG. 12: a sectional view at location XII according to FIG. 11.

FIG. 1 shows a schematic exploded view of an extension guide 1. Accordingly, the extension guide 1 may comprise a drawer rail 50 and a carcass rail 10.

The drawer rail 50 may be fixed to a movable furniture part, in particular to a drawer. As shown in FIG. 1, a drawer stop 54 may be provided on the drawer rail 50 for this purpose. Further coupling points or fastening structures for a direct or indirect coupling to the movable furniture part may be provided.

The carcass rail 10 may be fixed to a furniture carcass, for example to a cabinet. As shown in FIG. 1, the carcass rail 10 may comprise a fastening section 11 provided with mounting bores 11.1. In this case, the carcass rail 10 may be fixed to the furniture carcass with suitable fixing means, for example with screws passing through the mounting bores 11.1 and engaging with the furniture carcass.

The carcass rail may further comprise a bottom 12 that may adjoin the fastening section 11 at a right angle. The side section 13 may adjoin the bottom 12 at a right angle at an opposite side thereof. Adjoining the side section 13 at a right angle, an upper section of the carcass rail 10 may be provided which may on its upper side provide a support surface 14.

As can be further seen in FIG. 1, the extension guide 1 may additionally comprise a center rail 30 arranged between the carcass rail 10 and the drawer rail 50.

To allow a linear movement of the movable furniture part in an extension direction 2, for instance to allow opening and closing of a drawer, the drawer rail 50 may be linearly movable relative to the carcass rail 10 along the extension direction 2. The center rail 30 may also be linearly movable relative to the carcass rail 10 along the extension direction 2. Further, the center rail 30 and the drawer rail 50 may be linearly movable relative to one another in the extension direction 2.

Preferably and according to the embodiment shown, linear movement of the center rail 30 relative to the carcass rail 10 may be enabled and/or facilitated by an inner carriage 20 arranged in between the center rail 30 and the carcass rail 10. The inner carriage 20 may transmit a load, for example a load due to the weight of the drawer, between the center rail 30 and the carcass rail 10. The inner carriage 20 may be linearly movable along the extension direction 2, and may be movable relative to the carcass rail 10 and/or the center rail 30.

Similarly, linear movement of the drawer rail 50 relative to the center rail 30 may be enabled and/or facilitated by an outer carriage 40 arranged in between the center rail 30 and the drawer rail 50. The outer carriage 40 may transmit a load, for example a load due to the weight of the drawer, between the drawer rail 50 and the center rail 30. The outer carriage 40 may be linearly movable along the extension direction 2, and may be movable relative to the center rail 30 and/or the drawer rail 50.

FIG. 1 further shows that the extension guide 1 may comprise a first running surface 61 and a second running surface 65 as well as a first synchronizing wheel 62 and a second synchronizing wheel 63, which may be understood to be parts of a synchronizing device 60 (cf. FIGS. 4 and 5). The synchronizing device 60 may be provided for setting position and/or speed relations between two or more of the carcass rail 10, the inner carriage 20, the center rail 30, the outer carriage 40 and/or the drawer rail 50. Preferably, and as shown in the embodiment according to the figures, the synchronizing device 60 enables a defined speed and position relationship between the carcass rail 10, the center rail 30 and the outer carriage 40. In other words, the synchronizing device 60 may be effective between the carcass rail 10 and the outer carriage 40. The synchronizing device 60 will be discussed in more detail further below.

As shown in FIG. 1, the first running surface 61 may be provided on an attaching element 70 that may be detachably connected to the carcass rail 10. In other words, the first running surface 61 of the embodiment shown in the figures is connected indirectly to the carcass rail 10. It is conceivable, however, to provide a first running surface 61 that is connected directly to the carcass rail 10, for example is provided integrally with the carcass rail 10. In any case, it is preferable that the first running surface 61 is connected to the carcass rail 10 in a stationary manner. That is, preferably the first running surface 61 does not move relative to the carcass rail 10 during a movement of the movable furniture part, the center rail 30, the inner carriage 20, the outer carriage 40 and/or the drawer rail 50.

Further, FIG. 1 shows that the second running surface 65 may be directly connected to the outer carriage 40. As in the embodiment shown, preferably the second running surface 65 is designed integrally with the outer carriage 40. However, it is conceivable that the second running surface 65 is connected indirectly to the outer carriage 40, for example provided separate from and connected to the outer carriage 40, in particular similar to the first running surface 61 preferably being indirectly connected to the carcass rail 10.

The first running surface 61 and the second running surface 65 may preferably both be designed as toothed racks. However, it is also conceivable that the running surfaces 61, 65 are designed another way, for example designed with a smooth surface. Furthermore, the running surfaces 61, 65 need not both be designed in the same manner. For instance, only one of the running surfaces 61, 65 may be designed as a toothed rack.

As stated above, the synchronizing device 60 may further comprise a first synchronizing wheel 62 and a second synchronizing wheel 63. As can be seen in FIG. 1, the first synchronizing wheel 62 and the second synchronizing wheel 63 may be rotatably mounted on the center rail 30.

Preferably the second synchronizing wheel 63 and the first synchronizing wheel 62 are arranged on opposite sides of a wall of the center rail 30. In the embodiment shown, the synchronizing wheels 62, 63 are arranged on opposite sides of a second side wall 33 of the center rail 30, the second synchronizing wheel 63 being on the outer side and the first synchronizing wheel 62 being on the inside. As illustrated in FIG. 2, the first synchronizing wheel 62 may partially reach through a synchronizing wheel breakthrough 32.1 provided in the top wall 32 of the center rail 30.

In vicinity to the synchronizing wheel breakthrough 32.1 a support plate 36 may further be provided on the center rail 30. As shown in the figures, the support plate 36 may be essentially shaped as a platelet. The support plate 36 may be fixed to the top wall 32 in any suitable manner and may partially protrude over the edge formed between the top wall 32 and the second side wall 33. Accordingly, as shown in FIG. 2, the support plate 36 may be located partially above the second synchronizing wheel 63.

A preferred way of mounting the synchronizing wheels 62, 63 to the center rail 30 can perhaps best be explained with reference to FIG. 3, which shows a schematic exploded view of components shown in FIG. 2.

Accordingly, the second synchronizing wheel 63 may comprise a head portion 63.1 adjoining a shaft portion 63.2. The head portion 63.1 may be configured to interact with the second running surface 65, preferably to roll on the second running surface 65. In this context, the second synchronizing wheel 63 may preferably be designed as a pinion that is configured to mesh with the second running surface 65, the second running surface 65 preferably being designed as a toothed rack as described above.

Similarly, the first synchronizing wheel 62 may be configured to interact with the first running surface 61, preferably to roll on the first running surface 61. In this context, the first synchronizing wheel 62 may preferably be designed as a pinion that is configured to mesh with the first running surface 61, the first running surface 61 preferably being designed as a toothed rack as described above.

However, if the first running surface 61 and/or the second running surface 65 are designed in a different way, for instance with a smooth surface, the first synchronizing wheel 62 and/or the second synchronizing wheel 63 may be configured accordingly, respectively.

The first synchronizing wheel 62 may preferably, as in the shown embodiment, have a diameter about twice a diameter of the second synchronizing wheel 63. Diameters of the synchronizing wheels 62, 63 may be diameters measured in regions of the synchronizing wheels 62, 63 configured to interact with the respective running surface 61, 65. For example, a diameter of the second synchronizing wheel 63 may be measured at the head portion 63.1. A diameter of a synchronizing wheel 62, 63 may be an outer diameter. When a synchronizing wheel 62, 63 is designed as a pinion, a diameter may be an inside diameter, an outside diameter or a pitch diameter of the pinion.

Returning to the second synchronizing wheel 63, the shaft portion 63.2 may preferably be configured to be at least partially accommodated in a hub 62.1 of the first synchronizing wheel 62. In other words, by an at least partial accommodation of the shaft portion 63.2 of the second synchronizing wheel 63 in the hub 62.1 of the first synchronizing wheel 62, the synchronizing wheels 62, 63 may be attached to one another.

It is further preferable that both the shaft portion 63.2 and the hub 62.1 are provided with at least partially matching profiles to enable a torque to be transmitted between the two at least partially in a positive-locking manner. For this purpose, as shown in the figures, preferably a spline 63.3 may be provided at the shaft portion 63.2 that is configured to engage with an at least partially corresponding mating spline 62.2 provided at the hub 62.1. The spline 63.3 and the mating spline 62.2 may be of any suitable type.

Further, the center rail 30 may comprise a shaft opening 33.4 through which the shaft portion 63.2 can be guided. The shaft opening 33.4 may be designed as a bore in a wall of the center rail 30, preferably as shown as a bore in the second side wall 33.

As can be further gathered from FIG. 3, a synchronizing wheel holder 64 may be provided to mount the first and second synchronizing wheels 62, 63 to the center rail 30. The synchronizing wheel holder 64 may comprise a holding projection 64.3 that may, as depicted, be designed as a tongue. The holding projection 64.3 may be held at a retaining means 33.3 provided at the second side wall 33 of the center rail 30. When the holding projection 64.3 is designed as a tongue, the retaining means 33.3 may be appropriately shaped as a hook in order to hold the holding projection 64.3 to the second side wall 33.

The synchronizing wheel holder 64 may further comprise a holding lug 64.5 that may be received in a latching aperture 33.5 of the center rail 30. As can be seen in FIG. 3, the holding lug 64.5 may preferably be designed as a hook that engages through the latching aperture 33.5. To further secure the position of the synchronizing wheel holder 64 against the center rail 30, additionally or alternatively, a latching projection 64.4 may be provided on the synchronizing wheel holder 64 that is configured to be received in a latching receptacle 33.6 of the center rail 30. Preferably, the latching receptacle 33.6 is provided on the second side wall 33 of the center rail 30.

The synchronizing wheel holder 64 may comprise a receiving space 64.1 in which the first synchronizing wheel 62 can be received partially. Within the receiving space 64.1, a bearing receptacle 64.6 may be provided, in which a bearing projection 63.4 projecting from the shaft portion 63.2 of the second synchronizing wheel 63 can be received and rotatably supported. Further, the synchronizing wheel holder 64 may comprise a bearing portion 64.2 that may be configured to support a region of the shaft portion 63.2 that is not inserted into the hub 62.1. As shown in the presented embodiment, the bearing portion 64.2 may preferably be designed as a bore and may further preferably be located opposite to the bearing receptacle 64.6.

In this way, the synchronizing wheel holder 64 may first be secured to the center rail 30 by engaging the holding projection 64.3 with the retaining means 33.3 and/or by engaging the holding lug 64.5 with the latching aperture 33.5 and/or by engaging the latching projection 64.4 with the latching receptacle 33.6. It should be noted that the bearing portion 64.2 of the synchronizing wheel holder 64 may at least partially project into the shaft opening 33.4 as can be best seen in FIG. 5. This may provide additional support of the synchronizing wheel holder 64 on the center rail 30.

Once the synchronizing wheel holder 64 is secured to the center rail 30, the first synchronizing wheel 62 may be partially inserted into the receiving space 64.1. Afterwards the second synchronizing wheel 63 may be guided with its shaft portion 63.2 through the shaft opening 33.4, the bearing portion 64.2 and the hub 62.1 toward the bearing receptacle 64.6, where it may be received with its bearing projection 63.4. The synchronizing wheels 62, 63 may in this state be rotatably mounted on the center rail 30.

FIG. 4 shows a schematic perspective view of the center rail 30 in combination with the synchronizing device 60 and FIG. 5 shows a sectional view at location V according to FIG. 4.

From the sectional view of FIG. 4 it is apparent that the second synchronizing wheel 63 may mesh with the second running surface 65 provided on the outer carriage 40, and that the first synchronizing wheel 62 may mesh with the first running surface 61 provided on the attaching element 70. Note that FIGS. 4 and 5 do not show the carcass rail 10 to which the attaching element 70 may be attached. As stated above, it is conceivable in the alternative, that the first running surface 61 may also be directly provided on the carcass rail 10.

As can be seen in FIG. 5, the outer carriage 40 may be provided with a slot 49 that may be arranged along the extension direction 2. The slot 49 may partially accommodate the support plate 36. This may ensure that the outer carriage 40 does not lift off the center rail 30. As the second running surface 65 is connected to the outer carriage 40 and the second synchronizing wheel 63 is connected to the center rail 30, the interaction of the support plate 36 and the slot 49 may ensure proper rolling of the second synchronizing wheel 63 on the second running surface 65, in particular proper meshing of the synchronizing wheel 63 with the second running surface 65.

FIG. 6 shows a schematic exploded view of the outer carriage 40. As shown in FIG. 6, the outer carriage 40 may be formed of a plurality of segments 40.1, 41, 42 which may be detachably connected to one another. Preferably, the outer carriage 40 may comprise a first running segment 41, a second running segment 42 and a base segment 40.1.

The running segments 41, 42 may be provided with third guide means 46. The third guide means 46 may preferably be designed as rollers, as in the shown embodiment. The third guide means 46 may be held within third guide means receptacles 46.1 that may be designed as openings within the running segments 41, 42. The third guide means 46 may be rotatable about an axis that is perpendicular to the extension direction 2, preferably an axis that is horizontal. In this way, the running segments 41, 42 may be guided in the extension direction 2 and supported in a transverse direction, preferably in the vertical direction. In other words, the running segments 41, 42 may be supported by the third guide means 46 against the top wall 32 of the center rail 30 (cf. FIG. 5).

As shown in FIG. 6, the running segments 41, 42 may each comprise more than one third guide means receptacle 46.1. However, not all third guide means receptacles 46.1 need necessarily be equipped with a third guide means 46. Rather, the number of third guide means 46 to be disposed within third guide means receptacles 46.1 may be chosen based on the expected load to be transmitted by the running segments 41, 42. In this way, the same design of running segments 41, 42 may be usable with different extension guides 1 which may face different load requirements.

As can further be gathered from FIG. 6, the second running segment 42 may comprise third lateral guide means 45.1. The third lateral guide means 45.1 may be provided on a lateral running segment 45 of the second running segment 42. Preferably, the third lateral guide means 45.1 are designed as rollers. The third lateral guide means 45.1 may essentially be held at the second running segment 42 in the same way as the third guide means 46. However, the third lateral guide means 45.1 may guide the second running segment 42 in the extension direction 2 provide support in a transverse direction, preferably in the horizontal direction. In other words, the second running segment 42 may be supported by the third lateral guide means 45.1 against the first side wall 31 of the center rail 30 (cf. FIG. 5). Hence, the third lateral guide means 45.1 may be rotatable about a vertical axis.

While not visible in the figures, it is preferable that also the first running segment 41 is provided with third lateral guide means 45.1.

The running segments 41, 42 may be detachably connected to the base segment 40.1 and thereby may be detachably connected to one another via the base segment 40.1. As shown in FIG. 6, the connection may be established by latching projections 40.2 protruding from a body of a running segment 41, 42 and/or the base segment 40.1 and correspondingly designed latching receptacles 41.1 provided on the respective other segment 41, 42, 40.1 to be connected. The latching projections 40.2 may be receivable in the latching receptacles 41.1.

Preferably, the latching projections 40.2 further comprise a latching element 40.3 that may be, as shown in FIG. 6, designed as a latching nose. The latching element 40.3 may engage or snap in at least partially behind a corresponding latching stop 41.2 provided at the latching receptacle 41.1.

In the shown embodiment, the first running segment 41 is equipped with two latching receptacles 41.1 and the base segment 40.1 is equipped with two matching latching projections 40.2. Further, the second running segment 42 is equipped with two latching projections 40.2 and the base segment 40.1 is equipped with two matching latching receptacles 41.1. However, different combinations are conceivable.

The outer carriage 40 may be composed such that the running segments 41, 42 are located at opposing end regions of the base segment 40.1 in the extension direction 2. Preferably, the first running segment 41 may be connected to the base segment 40.1 in a first end region and the second running segment 42 may be connected to the base segment 40.1 in a second end region viewed in the extension direction 2.

The base segment 40.1 may comprise a top part 40.4 that may be configured to be arranged at least partially above the top wall 32 of the center rail 30 (cf. FIG. 5). As discussed before, the second running surface 65 may be connected directly or indirectly to the outer carriage 40. In the embodiment shown, the second running surface 65 is integrally formed with the base segment 40.1 of the outer carriage 40, angled off from the top part 40.4 so that it faces the second synchronizing wheel 63, as can be best seen in FIGS. 4 and 5.

Further, the outer carriage 40 may be equipped with fourth lateral guide means 48. As in the presented embodiment, the fourth lateral guide means 48 may be held on side guides 47 that are angled off from the top part 40.4. Similar to the third lateral guide means 45.1 of the second running segment 42, the fourth lateral guide means 48 may preferably be designed as rollers rotatable about a vertical axis. The fourth lateral guide means 48 may be partially received in fourth lateral guide means receptacles 48.1. The fourth lateral guide means receptacle 48.1 may be arranged at the side guides 47 of the base segment 40.1.

By the fourth lateral guide means 48, guidance of the base segment 40.1 in the extension direction 2 as well as support in horizontal direction transverse to the extension direction 2 may be achieved. For example, as in the presented embodiment, the fourth lateral guide means 48 may roll on an outer side of the second side wall 33 (cf. FIG. 5). In other words, the fourth lateral guide means 48 and the third lateral guide means 45.1 may be arranged on opposite sides of the center rail 30.

Preferably the outer carriage 40 may be composed such that the side guides 47 are located at opposing end regions of the base segment 40.1 in the extension direction 2. In this way, the side guides 47 may not interfere with the engagement of the second synchronizing wheel 63 and the second running surface 65.

As can be further seen in FIG. 6, the second running segment 42 may further be equipped with elastically deformable spring attachments 42.1, 42.2. One spring attachment 42.1 may be connected to the lateral running segment 45 of the second running segment 42. This spring attachment 42.1 may serve the purpose of softening an impact of the second running segment 42 with a stop 31.2 located on the first side wall 31 of the center rail 30 (cf. FIGS. 1 and 4). Additionally, one spring attachment 42.2 may be arranged such that it is located above the top wall 32 of the center rail 30. This spring attachment 42.2 may serve the purpose of softening an impact of the second running segment 42 with a stop 56 located on a side wall 51 of the drawer rail 50 (cf. FIG. 12).

FIG. 7 shows a schematic exploded view of the inner carriage 20 and FIG. 8 provides an enlarged view of detail VIII according to FIG. 7. As depicted, the inner carriage 20 may be formed of a plurality of segments 21, 24 which may be detachably connected to one another. Preferably, the inner carriage 20 may comprise two carriage segments 21 and a linking segment 24.

The carriage segments 21 may be provided with second guide means 26. The second guide means 26 may preferably be designed as rollers, as in the shown embodiment. The second guide means 26 may be held within roller receptacles 26.1 that may be designed as openings within upper parts 23 and base parts 22 of the carriage segments 21. The second guide means 26 may be rotatable about an axis that is perpendicular to the extension direction 2, preferably an axis that is horizontal. In this way, the carriage segments 21 may be guided in the extension direction 2 and supported in a transverse direction, preferably in the vertical direction. In other words, the carriage segments 21 may be supported by the second guide means 26 against the support surface 14 of the carcass rail 10 (cf. FIG. 12).

As shown in FIG. 7, the carriage segment 21 may each comprise more than one roller receptacle 26.1. However, not all roller receptacle 26.1 need necessarily be equipped with a second guide means 26. Rather, the number of second guide means 26 to be disposed within the roller receptacle 26.1 may be chosen based on the expected load to be transmitted by the carriage segments 21. In this way, the same design of carriage segments 21 may be usable with different extension guides 1 which may face different load requirements.

As can further be gathered from FIGS. 7 and 8, the carriage segments 21 may comprise first lateral guide means 28. The first lateral guide means 28 may be provided on the base parts 22 of the carriage segments 21. Preferably, the first lateral guide means 28 are designed as rollers rotatable about a vertical axis. The first lateral guide means 28 may guide the carriage segments 21 in the extension direction 2 and provide support in a transverse direction, preferably in the horizontal direction. In other words, the carriage segments 21 may be supported by the first lateral guide means 28 against a side section 13 of the center rail 30 (cf. FIG. 12).

As seen in FIG. 8, the base part 22 and the upper part 23 of the carriage segment 21 may be connected by a wall section 23.1 on one lateral side of the carriage segment 21. In this way, a rail receptacle 27 may be formed between the base part 22 and the upper part 23. The rail receptacle 27 may serve to receive a part of the upper wall of the carcass rail 10 (cf. FIG. 12). The upper wall may comprise the support surface 14 on its upper side.

Further, the carriage segment 21 may be equipped with guide projections 23.2 projecting from the upper part 23 in a lateral direction and downwards toward the base part 22. The guide projections 23.2 may be configured to engage at least partially and/or temporally with the side section 13 of the carcass rail 10 to improve lateral guidance of the carriage segments 21, as can be seen in FIG. 12.

The carriage segments 21 may be detachably connected to the linking segment 24 and thereby may be detachably connected to one another via the linking segment 24. As shown in FIGS. 7 and 8, the connection may be established by means of a connecting element 24.2 and a connecting counter element 21.3. In the embodiment according to the figures, the connecting counter elements 21.3 are arranged at the carriage segments 21 and the connecting elements 24.2 are arranged at the linking segment 24. However, different arrangements are conceivable.

As best visible in FIG. 8, the connecting counter element 21.3 may be provided at the base part 22 of the carriage segment 21.

The connecting counter element 21.3 may comprise a connecting receptacle 21.4 in which a connecting insert 24.4 of the connecting element 24.2 may be received. Accordingly, the connecting receptacle 21.4 may be designed at least partially corresponding to the connecting insert 24.4.

As can be further seen in FIG. 8, adjacent to the connecting insert 24.4, the connecting element 24.2 may comprise a connecting neck 24.6. The connecting neck 24.6 may have a smaller cross section than the connecting element 24.2. In this way, the connecting neck 24.6 may be received in a connecting recess 21.6 that may be formed in a wall of the connecting receptacle 21.4.

Further, within the connecting receptacle 21.4 there may be one or more connecting projections 21.5. The connecting projection 21.5 may protrude from a wall of the connecting receptacle 21.4 toward the inside thereof. Consequently, the connecting insert 24.4 may comprise one or more connecting retractions 24.5 that may be partially correspondingly shaped to the connecting projection 21.5. The connecting projection 21.5 may snap into the connecting retraction 24.5 during insertion of the connecting insert 24.4 into the connecting receptacle 21.4.

In the way described above, force transmission between the connecting element 24.2 and the connecting counter element 21.3 may be achieved essentially in a positive-locking manner. However, it is conceivable that at least partially, force transmission may be achieved in a friction-locking manner. In particular, an interference fit may at least to some degree be provided between the connecting element 24.2 and the connecting counter element 21.3. This may be in addition to the components of the connecting element 24.2 and the connecting counter element 21.3 described above, that may provide largely a positive-locking force transmission.

In the embodiment shown, the carriage segments 21 and the linking segment 24 are arranged in succession to one another in the extension direction 2. As can be seen in the figures, a first carriage segment 21 is followed by the linking segment 24 which is in turn followed by a second carriage segment 21. In this way, the same type of carriage segments 21 may be used for different lengths of rails of the extension guide 1. In order to adapt the inner carriage 20 for longer or shorter rails, only the length of the linking segment 24 may need to be adjusted.

As can be further seen in FIG. 7, the carriage segments 21 may further be equipped with elastically deformable spring attachments 21.2. The spring attachments 21.2 may be connected to the base parts 22 of the carriage segments 21. The spring attachment 21.2 of the carriage segment 21 that is shown in the left of FIG. 7 may serve the purpose of softening an impact of the carriage segment 21 with a first stop 14.1 located below the support surface 14 of the carcass rail 10 (cf. FIG. 1). The spring attachment 21.2 of the carriage segment 21 that is shown in the right of FIG. 7 may serve the purpose of softening an impact of the carriage segment 21 with a second stop 13.3 provided at the side section 13 of the carcass rail 10 (cf. FIG. 1).

As discussed above, the first running surface 61 may be provided on an attaching element 70 that may be detachably connected to the carcass rail 10. The attaching element 70 may be one part. However, preferably and as per the embodiment shown in the figures, the attaching element 70 may be designed in multiple parts. For example, as shown in FIG. 1, the attaching element 70 may comprise a first attaching segment 71 and a second attaching segment 75 which may follow one another in the extension direction 2. The first running surface 61 may thus be arranged on both attaching segments 71, 75.

A preferred way of detachably connecting the attaching element 70 to the carcass rail 10 may be as follows: As shown in FIG. 1, receiving elements 13.1 may be provided on the side section 13 of the carcass rail 10. The receiving elements 13.1 may be hook shaped. Corresponding to the receiving elements 13.1, the attaching element 70 may comprise receptacles 73 (cf. FIG. 5) that may receive the receiving elements 13.1. The receptacles 73 may be accessible from below, so that the attaching element 70 may be connected to the carcass rail 10 by placing the receptacles 73 above the receiving elements 13.1 and subsequently lowering the attaching element 70. Owing to the hook shaped design of the receiving element 13.1 and the corresponding design of the receptacles 73, the attaching element 70 may be supported against the carcass rail 10 at least both in the extension direction 2 and in the lateral horizontal direction perpendicular to the extension direction 2.

Further, the attaching element 70 may comprise latching projections 74 projecting toward the side section 13 of the carcass rail 10 (cf. FIG. 5). The latching projections 74 may be received in correspondingly designed positioning receptacles 13.2 provided on the side section 13. The latching projections 74 may snap into the positioning receptacles 13.2 during lowering of the attaching element 70, i.e., while inserting the receiving elements 13.1 into the receptacles 73.

As can be seen in FIG. 1, the extension guide 1 may comprise first guide means 72 for guiding the center rail 30 and for supporting the center rail 30 in the horizontal direction. The first guide means 72 may be designed as first guide rollers 72.2 rotatable about a vertical axis. The first guide means 72 may be connected to the carcass rail 10. Preferably, and as shown in the figures, the first guide means 72 are provided on the attaching element 70.

For this purpose, the attaching element 70 may comprise first guide means receptacles 72.1. The first guide means receptacle 72.1 may partially accommodate the first guide rollers 72.2. Preferably the first guide rollers 72.2 are rotatably mounted by means of roller pins 72.3 that may be rotatably received in pin receptacles 72.4 that may be provided within the first guide means receptacles 72.1.

As shown in FIG. 1, the attaching element 70 may comprise more than one first guide means receptacle 72.1. Further, each of the attaching segments 71, 75 may comprise more than one first guide means receptacle 72.1. However, not all first guide means receptacles 72.1 need necessarily be equipped with a first guide means 72. Rather, the number first guide means 72 to be disposed within first guide means receptacles 72.1 may be chosen based on the expected load to be transmitted between the carcass rail 10 and the center rail 30. In this way, the same design of attaching elements 70 and/or attaching segments 71, 75 may be usable with different extension guides 1 which may face different load requirements.

As best seen in FIG. 12, at least part of the first guide means 72 may be in contact with an inner side of the second side wall 33 of the center rail 30. In particular, they may roll on the inner side of the second side wall 33 during linear movement of the movable furniture part.

Returning to FIG. 1, it is apparent that first guide means 72 may be provided essentially over the whole length of the carcass rail 10. In this way, improved lateral guidance of the center rail 30 on the carcass rail 10 is achieved. However, it is also conceivable that only at least two thirds or at least three quarters of the length of the carcass rail 10 are equipped with first guide means 72, for example being designed taking into account the requirements for guiding the center rail 30.

FIG. 11 shows a schematic side view of an extension guide 1 and FIG. 12 shows a sectional view at location XII according to FIG. 11. The way a load, for example a load due to a weight of a drawer, is transmitted to the furniture carcass is perhaps best explained based on FIG. 12.

As stated above, the drawer rail 50 may be attached to the movable furniture part. A vertical load may be transmitted between the top wall 52 of the drawer rail 50 and the top wall 32 of the center rail 30 through the third guide means 46 of the outer carriage 40. A horizontal load may be transmitted between one side wall 51 of the drawer rail 50 and the first side wall 31 of the center rail 30 through the third lateral guide means 45.1 of the outer carriage 40. Further, a horizontal load may be transmitted between another side wall 51 of the drawer rail 50 and the second side wall 33 of the center rail 30 through the fourth lateral guide means 48 of the outer carriage 40. Additionally, vertical loads that may lead to a lifting-off of the drawer rail 50 from the center rail 30 may be compensated by lifting rollers 35 provided on side walls 31, 33 of the center rail 30 that may engage with bent off portions 51.1, 53.1 adjoining the side walls 53 of the drawer rail 50 (cf. FIG. 1).

Between the top wall 32 of the center rail 30 and the support surface 14 of the carcass rail 10, a vertical load may be transmitted through the second guide means 26 of the inner carriage 20. Further, vertical loads may be transmitted between a first bend 31.1 angled off of the first side wall 31 of the center rail 30 on its bottom side and the upper segment of the carcass rail 10 through the second guide means 26 provided on the base part 22 of the inner carriage 20. Horizontal loads may be transmitted between the first side wall 31 of the center rail 30 and the side section 13 of the carcass rail 10 through the first lateral guide means 28 of the inner carriage 20. Further, horizontal loads may be transmitted between the second side wall 33 of the center rail 30 and the side section 13 of the carcass rail 10 through the first guide means 72 that may be provided on the attaching element 70.

In the following, the function of the presented embodiment of an extension guide 1 according to the invention is explained based on an extension (opening) and a retraction (closing) operation of the movable furniture part.

When the movable furniture part is in a closed state, the extension guide 1 may be in a retracted state. The retracted state may correspond to the state shown in FIG. 11.

In the retracted state, a movement of the inner carriage 20 against the extension direction 2 may be prohibited by the spring attachment 21.2 facing against the extension direction 2 resting on the first stop 14.1 of the carcass rail 10.

Movement of the center rail 30 against the extension direction 2 may be prohibited by the outer carriage 40 resting against a stop 32.2 provided on the center rail 30 (cf. FIG. 4). This may inhibit movement of the outer carriage 40 against the extension direction 2. Thus, rotation of the second synchronizing wheel 63 in a counterclockwise direction as seen in FIG. 1 may be inhibited. Consequently, because the first synchronizing wheels 62, 63 may be connected in a rotationally fixed manner, rotation of the first synchronizing wheel 62 in the counterclockwise direction may be inhibited. Based on this, relative movement between the first synchronizing wheel 62 and the first running surface 61 may be inhibited, thus inhibiting relative movement between the center rail 30 and the carcass rail 10.

Movement of the drawer rail 50 against the extension direction 2 may be prohibited by the stop 56 of the drawer rail 50 resting against a counter stop 41.3 located at the first running segment 41 (cf. FIGS. 1, 4 and 6).

During an opening movement of the drawer, the drawer rail 50 may be moved in the extension direction 2 relative to center rail 30. The outer carriage 40 may be moved relative to the center rail 30 by means of the third guide means 46, the fourth lateral guide means 48 and the third lateral guide means 45.1 rolling in between respective walls of the outer carriage 40 and the center rail 30. The outer carriage 40 may move relative to the center rail 30 at half the speed of the relative movement between the drawer rail 50 and the center rail 30.

The relative movement of the outer carriage 40 and the center rail 30 may cause rolling of the second synchronizing wheel 63 on the second running surface 65. In this way, the second synchronizing wheel 63 may be rotated by the relative movement between the outer carriage 40 and the center rail 30.

The rotation of the second synchronizing wheel 63 may be transmitted to the first synchronizing wheel 62, that may be connected to the first synchronizing wheel 62 in a rotationally fixed manner. A thus-induced rotation of the first synchronizing wheel 62 may cause the first synchronizing wheel 62 to roll on the first running surface 61. That is, rotation of the first synchronizing wheel 62 may cause relative motion between the center rail 30 and the first running surface 61, and thus may cause relative motion between the center rail 30 and the carcass rail 10.

The inner carriage 20 may be moved relative to the carcass rail 10 by means of the second guide means 26 and first lateral guide means 28 rolling in between respective walls of the center rail 30 and the carcass rail 10. The inner carriage 20 may move relative to the carcass rail 10 at half the speed of the relative movement between the center rail 30 and the carcass rail 10.

The speed relations between moving rails and/or carriages may depend on the ratio of the diameter of the first synchronizing wheel 62 to the second synchronizing wheel 63.

In the shown embodiment, the synchronizing wheels 62, 63 are mounted on the center rail 30, the second running surface 65 is connected to the outer carriage 40 and the inner carriage 20 is provided between carcass rail 10 and center rail 30. If the above-mentioned ratio of diameters is chosen to be 2, the speed relation between carcass rail 10, inner carriage 20, center rail 30, outer carriage 40 and drawer rail 50 may be 0:1/6:1/3:2/3:1 (speed of drawer rail 50 assumed to be 1). If the ratio is chosen to be 2.0, as preferred and as in accordance with the embodiment shown in the figures, the relation may be 0:1/4:1/2:3/4:1. This may be a preferred relation because it provides an even distribution of speeds and travel length of the rails and carriages of the extension guide 1 during extension and retraction. When the movable furniture part is in a fully open state, the extension guide 1 may be in a fully extended state.

In the extended state, a further movement of the inner carriage 20 in the extension direction 2 may be prohibited by the spring attachment 21.2 facing in the extension direction 2 resting on the second stop 13.3 of the carcass rail 10.

Further movement of the center rail 30 in the extension direction 2 may be prohibited by the outer carriage 40 resting against a stop 31.2 provided on the center rail 30 (cf. FIG. 4) with its spring attachment 42.1. This may inhibit further movement of the outer carriage 40 in the extension direction 2. Thus, rotation of the second synchronizing wheel 63 in a clockwise direction as seen in FIG. 1 may be inhibited. Consequently, because the first synchronizing wheels 62, 63 may be connected in a rotationally fixed manner, rotation of the first synchronizing wheel 62 in the clockwise direction may be inhibited. Hence, relative movement between the first synchronizing wheel 62 and the first running surface 61 may be inhibited, thus inhibiting further relative movement between the center rail 30 and the carcass rail 10 in the extension direction 2.

Further movement of the drawer rail 50 in the extension direction 2 may be prohibited by a stop of the drawer rail 50 located at the inside of the side wall 51 (not shown in the figures) resting on a spring attachment 42.2 located at the second running segment 42 (cf. FIGS. 1, 4 and 6).

From the open state, closing of the movable furniture part may lead the extension guide 1 back to the retracted state described above. For the closing process, the same explanations are analogously valid that were made above for the opening process.