Patent Description:
It is known within the art to equip a cargo space, at for example a service vehicle, with different kinds of storing systems, like cupboards, shelves, boxes, tool holders, etc. Once the vehicle has been manufactured, a separate step of equipping the vehicle with different kind of interior, tailor made or modular, takes place. This step may also include to provide the cargo space with separate floor, walls, and ceiling, for example made by wood, depending on which type of interior is needed. This step may also include to directly fit for example specially adapted rails etc. to the insides of the cargo space.

Most holding devices for long items are designed for and positioned for storing, for example the ladder, outside the vehicle, most common on a roof rack on top of the vehicle. One problem with that is that the ladder is exposed for weather and dirt and another problem is a risk of theft. Further, it is often quite difficult to attach the ladder on top of the roof rack or to dismount the ladder from the roof rack, since most such vehicles are high. Therefore, solutions with holding devices for ladders and other long items, to securely hold and store ladders or the like inside a cargo space are developed. One problem with storing inside a cargo space is that mounting and removing for example the ladder often is difficult and time consuming, since it is crucial to store the ladder somewhere in the often very occupied cargo space, where it is out of way but easy to reach. Prior art solutions present different solution with straps or the like, to strap the ladder to rails or hooks attached to a wall or the ceiling inside the cargo space. For example, some prior art solutions present holding devices attached to an elongate rail attached to the ceiling and which rail extends from the back of the cargo space and forwards. A front holder may be slidingly arranged to the rail while a back holder is fixed to the rail in a determined position. A user may place one end of the ladder into the front holder and push the ladder forwards until the other end of the ladder is in position to be positioned into the back holder. Finally, a safety strap is used to secure the ladder at the back end.

Other solutions may comprise for example a cord or the like of a determined length and strength, which cord connects a fixed back holder with a movable front holder. This solution is used in the same way as presented above, but additionally, when the ladder is placed in the front holder and is pushed forwards, the cord is tensioned, and by that, the ladder is clamped between the holders.

One known solution for loading and unloading of a ladder outside a vehicle, on top of a vehicle roof, is presented in <CIT> which shows the features of the preamble of claim <NUM>. The solution provides a holder including a tiltable and length-adjustable roof rack on which a ladder may be loaded and clamped in a more or less upright position by a user, for example behind the vehicle. When loaded and clamped in a secure manner by means of adjustable upper and lower holders, the tiltable part of the roof rack, including the ladder may be tilted up and slid forwards along the roof part of the rack on top of the vehicle roof. The holder comprises a ladder latching mechanism where a spring-biased lever is arranged to cooperate with a toothed rack for and the lever is spring-biased against the toothed rack by a compression spring. The ladder is clamped between the first and second holders and is released by pressing down a pedal, wherein the lower holder is caused to descend, wherein the lever will "click" along the toothed rack until the feet of the ladder engage the ground and the ladder's rungs will no longer be captured by the upper holder and the lower holder.

One known solution for folding and unfolding a tarpaulin structure is presented in <CIT>. The tarpaulin structure comprises a plurality of brackets, wherein adjacent brackets are coupled to each other by means of a kinematic connecting rod assembly that folds when a folding top-frame is collapsed.

Prior art solutions presented above first of all lack flexibility in combination with an easy way of "loading/unloading" the long item, for example the ladder. When loading the ladder, it is convenient to have a counterforce to the forward motion of the ladder since this prevents the front holder to slide away from the user while applying the ladder to the holder and while pushing it forwards. The solution with the cord attached between the two holders solve that problem, but this solution is not flexible since the position of the back holder is fixed, why the stored ladder may not be moved out of way, when not used under a period of time. Another drawback with the "cord-solution" is that the length and the strength of cord must be adapted to the length of the ladder, why the solution must be adapted every time the holder device is to be mounted to a vehicle. Often the length of the ladder or the item to be stored is not known when equipping the vehicle, or the item may be replaced during the lifetime of the service vehicle, why the solution is not flexible.

It is an object of the invention to address at least some of the problems and issues outlined above. It is possible to achieve these objects and others by a holding device as defined in the attached independent claims, which by its design is easy to use and provides great flexibility and secure fastening of an item like for example elongate items like a ladder or the like.

According to an aspect of the invention, a holding device which is arranged to be mounted to a surface, preferably to a ceiling inside a cargo space of a vehicle, is disclosed. The holding device comprises at least one elongate rail which extends between a first end and a second end. The rail further comprises a first side which is arranged to be fixedly attached to said surface, and a second side which is opposite the first side. Further, a first holder is movably connected at the second side of the rail and is further arranged to slide along the rail between the first and second ends of the rail. A second holder is arranged to be fixedly connected at the second side of the rail in an optionable position along the rail, between the first holder and one of the first and second ends of the rail. The first holder comprises a spring attached with a first end to the first holder and attached with a second end to a mount. The mount is arranged to be fixedly connected at the second side of the rail in an optionable position along the rail, between the first holder and the second holder.

By that, a flexible and convenient holding device is disclosed. The holding device is easy to use, since the user may place one end of for example a ladder into the first holder, which by the spring force of the spring is positioned near the mount. The mount is fixedly connected to the rail in a position which allows an easy reach for the user to position the first end (front) of the ladder on the first holder. When the user pushes the ladder forwards, the spring is tensioned and provides a counterforce to the forward motion, which prevent the first holder from sliding away from the user in an uncontrolled manner with risk of the ladder falling of the first holder. When the second end (back end) of the ladder comes into position of the second holder, the user positions the back end of the ladder into the second holder, wherein the ladder is securely clamped between the holders. By having a mount, which is to be positioned in any position between the first (front) holder and the second (back) holder of the holding device, the "start position" of the first holder is optionable and if wanted and depending on the spring type the clamping force may be controlled. Further, by that also the second holder is arranged to be fixedly connected to the rail in an optionable position, the ladder is possible to store in an optionable position along the rail. This allows to store the ladder or the item to be stored in a position away from the back opening of the cargo space, which is convenient if the item or the ladder is not to be used for a period of time, and thus is out of way from the back opening of the vehicle. No prior art solutions provide such secure and flexible solution.

Further, the spring is a band spring. By using a band spring, the spring force is easy to adjust, by for example different windings of the band spring around a center of a strip or winder roll or the like.

Further, the band spring is a constant force band spring. A constant force spring may consist of a band material which is formed and prestressed into a tightly wound strip roll. The spring is used in a linear movement and gives a constant or almost constant spring force. The constant force band spring may be mounted in several ways and extended in part or all its length. There is no limit in principle for extraction speed and acceleration. Using a constant force spring band means that independently of the positioning of the mount, the spring force is substantially constant during the movement of the first holder.

According to an embodiment, the first holder comprises a housing arranged for accommodate the spring, wherein the first end of the spring is attached to the housing. The housing encloses and protects the first end of the spring and preferably the part of the spring which is not extended. If using a band spring, the housing encloses and thereby protects the winded part of the spring and a winder roll. The housing also comprises an outlet opening allowing the spring to extend out from the housing.

According to an embodiment, the mount comprises a first locking arrangement arranged for locking the mount to the rail in a locked state and arranged for unlocking the mount in an unlocked state, wherein the mount is arranged to slide along the rail in the unlocked state. The first locking arrangement may be a screw with a handle and a sliding block with a threaded hole, wherein the screw is in threaded connection with the sliding block. By tightening the screw, the sliding block is clamped to the rail and the mount is locked to the rail, and by loosening the screw, the sliding block is released from the clamped position and the mount is unlocked from the rail. By that, the mount is slidable along the rail and arranged to be locked in any position along the rail, which provides an easy setting of the "start position" of the first holder, which by its spring force of the spring is drawn towards the mount, which in the locked position acts as a stop for the mount. Further, in the unlocked position of the mount, the first holder position is optionable along the rail, which is convenient if the item/the ladder is to be stored in another position further in, in the forward direction (if also the second holder is moved).

According to an embodiment, the second holder comprises a second locking arrangement, which is arranged for locking the second holder to the rail in a locked state and arranged for unlocking the second holder in an unlocked state, wherein second holder is arranged to slide along the rail in the unlocked state. The second locking arrangement may be similar as the first locking arrangement (a screw with a handle and a sliding block with a threaded hole) and work in the same way as described above. By tightening the screw, the sliding block is clamped to the rail and the second holder is locked to the rail, and by loosening the screw, the sliding block is released from the clamped position and the second holder is unlocked from the rail. By that, the second holder is slidable along the rail and arranged to be locked in any position along the rail, which provides an easy setting which is adapted to the length of the item/the ladder. In the unlocked position, the second holder is possible to lock in an optionable along the rail, which is convenient for example when a ladder is not to be used for a period of time, and preferably is to be stored in a position out of way. Thus, both the first holder with its mount and the second holder must be unlocked, wherein the ladder in its clamped state between the holders may be moved to any position along the rail.

According to an embodiment, the first holder comprises a first shank which is arranged substantially perpendicular relative the rail and a second shank which is arranged substantially perpendicular relative the first shank at a first distance relative the rail. The second shank of the first holder protrudes in direction towards the second holder, and the first distance is optionable by that the first shank is adjustably arranged at the first holder or by that the second shank is adjustably arranged at the first shank. Such a solution is flexible since items or ladders with different design and width etc. may be stored by adjusting the distance between the second holder and the rail to correspond to the item/ladder.

According to an embodiment, the second holder comprises a third shank which is arranged substantially perpendicular relative the rail and a fourth shank which is arranged substantially perpendicular relative third shank at a second distance relative the rail. The fourth shank of the second holder protrudes in direction towards the first holder, and the second distance is optionable by that the third shank is adjustably arranged at the second holder or by that the fourth shank is adjustably arranged at the third shank. This, for the same reasons as presented above, to be able to adjust the second holder to the item to be clamped between the holders.

According to an embodiment, the rail comprises a first guiding space extending between the first end and the second end and with a first opening facing the second side of the rail. The first guiding space is arranged to guide the first holder, the mount and the second holder when moved along the rail, wherein the first holder, the mount and the second holder having first means, each arranged into the first guiding space and arranged to slide along the first guiding space of the rail. The dimensions of the first means and the guiding space are adopted for allowing a smooth guiding in the unlocked state of the second holder and the mount when moved to wanted positions as well as the sliding motion of the first holder during the storing of the item to be stored, such as a ladder.

According to an embodiment, the rail further comprises at least one first attachment device for attachment of the holding device to said surface, wherein the rail further comprises a second guiding space which extends between the first end and the second end and which has a second opening facing the first side of the rail. The second guiding space is arranged to accommodate and guide the at least one first attachment device, wherein the at least one first attachment device is arranged to be connected to the rail in an optionable position along the rail by having second means arranged into the second guiding space and arranged to slide along the second guiding space of the rail. Such a solution provides an easy adaption of where to fix the rail to the ceiling inside a cargo space, such that holding device is mountable in different kinds of interiors of the cargo space.

According to an embodiment, the rail further comprises at least one second attachment device for attachment of the holding device to said surface, wherein the rail further comprises a plurality of spaced apart holes arranged along the rail. The at least one second attachment device is arranged to be connected to the rail in an optionable position along the rail by having third means which are arrangeable into the at least one of the holes along the rail. This provides a plurality of positions for fixing the rail to the surface, i.e., to the inside ceiling of the cargo space. This second attachment device may be attached to the sides of the rail and provides another anchoring possibility compared to the first attachment device.

The holding device may comprise a number of first attachment devices, a number of second attachment devices or most preferred a combination of first and second attachment devices to allow different attachment possibilities to mount the holding device to a substrate like a ceiling in the cargo space of a vehicle.

According to an embodiment, the second holder comprises a strap which is arranged to secure an item to the second holder. This strap may be used as an extra safety and preferably has one end fixed to the second holder and another end which arranged to be secured to the second holder when the item/the ladder is clamped between the first and second holders.

Further possible features and benefits of this solution will become apparent from the detailed description below.

Briefly described, a holding device arranged for holding an item like a ladder or the like, is disclosed. The inventive design provides a convenient and secure solution for storing an item, preferably inside a cargo space of a vehicle. Of course, the inventive concept may be used outside a vehicle, for example on a roof rack or the like.

<FIG> shows a view of a holding device <NUM> according to the invention, seen obliquely from above. The holding device <NUM> is arranged to be mounted to a surface, preferably to a ceiling inside a cargo space of a vehicle. The holding device <NUM> comprises at least one elongate rail <NUM> which extends between a first end <NUM> and a second end <NUM> of the rail <NUM>. The first end <NUM> is preferably a front end referring to the cargo space and the traveling direction of a vehicle, and the second end <NUM> of the rail <NUM> is preferably a back end. The rail <NUM> further comprises a first side <NUM> which is arranged to be fixedly attached to said surface by means of at least one first attachment device <NUM>, positioned closer to the first end <NUM> of the rail <NUM>, and at least one second attachment device <NUM>, positioned closer to the opposite second end <NUM> of the rail <NUM>. The first attachment device <NUM> is movably arranged in an elongate slot/recess and lockable to the slot, which will be explained in detail below, and the second attachment device <NUM> is also movable and lockable to the rail <NUM>, but to the outside of the rail <NUM> via holes <NUM>. Of course, the mounting of the rail <NUM> to the ceiling of the vehicle may be done with only one kind of attachment device, and with a plurality of attachment devices, depending on the situation and demands of the holder device <NUM>. The rail <NUM> further comprises a second side <NUM> which is opposite the first side <NUM> and the holding device <NUM> further comprises a first holder <NUM>, which as mentioned above is a front holder, and which is movably connected at the second side <NUM> of the rail <NUM> and arranged to slide along the rail <NUM> between the first and second ends <NUM>, <NUM> of the rail <NUM>. The first holder <NUM> comprises a spring (not visible, see <FIG>) attached to the first holder <NUM> with one end and attached with another end to a mount <NUM>. The mount <NUM> is arranged to be fixedly connected at the second side <NUM> of the rail <NUM> in an optionable position along the rail <NUM>, between the first holder <NUM> and a second holder <NUM>. This will be further explained below. The second holder <NUM>, which as mentioned above is a back holder for the item, is arranged to be fixedly connected at the second side <NUM> of the rail <NUM> in an optionable position along the rail <NUM>, between the first holder <NUM> and one of the first and second ends <NUM>, <NUM> of the rail <NUM>, which in the preferred embodiment is the second end <NUM>.

The function of the holding device <NUM> is exemplified by the holding device <NUM> being a holder for a ladder. Typically, the holding device <NUM> is mounted in the ceiling of a cargo space of a service vehicle, in the traveling direction, and it is very common that the service vehicle has one or two back doors. To store the ladder inside the cargo space, the user opens the back doors of the vehicle and positions one end of the ladder on the first holder <NUM>, which is positioned at a convenient distance from the back doors by that the mount <NUM> is fixed to the rail <NUM> at about that distance. By that, the first holder <NUM> is by the spring force of the spring drawn to the mount <NUM> and abuts the mount <NUM>. When one end of the ladder is positioned onto the first holder <NUM>, the user pushes the ladder forwards, wherein the first holder <NUM> slides along the rail <NUM>, until the other end of the ladder is in position to be lifted and positioned onto the second holder <NUM>. When the ladder is positioned between the first and second holders, <NUM>, <NUM>, the ladder is clamped between them by the spring force of the spring. The second holder <NUM> preferably comprises a strap <NUM>, which may be used to secure the item/the ladder as an extra safety. More functionality will be explained below in relation to detail drawings of the first and second holders.

<FIG> show sections of the first holder <NUM>, the mount <NUM> and the rail <NUM>, seen obliquely from above in <FIG> and from the side in <FIG>. Further, the figures show how the first holder <NUM> and the mount <NUM> are attached to the rail <NUM>. The rail <NUM> preferably has an H-shape and comprises a first guiding space 14a (arranged as an elongate groove/slot), which extends between the first end <NUM> and the second end <NUM> of the rail <NUM> and with a first opening 14b facing the second side <NUM> of the rail <NUM> (see <FIG>). The first holder <NUM> and the mount <NUM> each has first means 20a, 24a which are arranged into the first guiding space 14a and which are arranged to slide along the first guiding space 14a of the rail <NUM>. Thus, the first guiding space 14a is arranged to guide the first holder <NUM> and the mount <NUM> via the first means 20a, 24a when the first holder <NUM> and the mount <NUM> are moved along the rail <NUM>.

The first holder <NUM> comprises a housing <NUM>, which is arranged for accommodate the spring <NUM>. The spring <NUM> is according to the preferred embodiment a band spring, and more preferred a constant force band spring <NUM>. A first end <NUM> of the spring <NUM> is attached to the housing <NUM> of the first holder <NUM>, more precise at a center/roll <NUM> of the housing <NUM>. A second end <NUM> of the spring <NUM> is attached to the mount <NUM>. The mount <NUM> comprises a first locking arrangement <NUM>, which is arranged to lock the mount <NUM> to the rail <NUM> in a locked state and arranged to unlock the mount <NUM> in an unlocked state. The first locking arrangement <NUM> preferably is a screw with a handle and the first means 24a of the mount <NUM> preferably is a sliding block with a threaded hole, wherein the screw is in threaded connection with the sliding block. By tightening the screw by rotating the handle clockwise, the sliding block is clamped to the rail <NUM> and the mount <NUM> is locked to the rail <NUM>. And vice versa, by loosening the screw counterclockwise, the sliding block is released from the clamped position and the mount <NUM> is unlocked from the rail <NUM>. By that, the mount <NUM> is slidable along the rail <NUM> and arranged to be locked in any position along the rail <NUM>. The mount <NUM> further functions as a stop for the first holder <NUM>, since the spring force of the spring <NUM> causes the first holder to move towards the mount <NUM> if no item (ladder) is positioned on the first holder <NUM> and is held in that position or pushed forwards. The setting of the locked position of the mount <NUM> to the rail <NUM> is preferably chosen to have a convenient and ergonomic position and distance from the back doors of the vehicle, for placing the first end of the ladder in an easy way.

The spring <NUM> is preferred to be a band spring and more preferred band spring with constant force, which means that the spring force is substantially constant, independently of how much of the band spring <NUM> is rolled out from its rolled state in the housing <NUM>, while pushing the first holder <NUM> forwards. This also means that even if the mount <NUM> is positioned near the back doors of the vehicle, the spring force is not substantially increased while pushing the first holder <NUM> a forwards into the cargo space, even if a long ladder or the like is to be stored in the cargo space of the vehicle. If another, not constant force band spring is used, the spring force could get rather high if the mount <NUM> is positioned in a convenient position near the back doors and if the ladder is long, wherein the travelling distance of the first holder <NUM> would be long. Thus, it would be needed an increasing force the longer distance the first holder is pushed, if a non-constant force spring is used.

To be able to receive an end of a ladder or an item, the first holder <NUM> comprises a first shank <NUM> which is attached to the housing <NUM> and thus is arranged perpendicular relative the rail <NUM>. At an outer end of the first shank <NUM>, a second shank <NUM> is arranged and protrudes in direction towards the second holder <NUM>, substantially perpendicular relative the first shank <NUM>. The second shank <NUM> functions as a support for an end of a ladder or the like. To be able to adapt the first holder <NUM> to different ladders or items with different heights, a first distance a between the second shank <NUM> and the rail <NUM> is optionable, by that the first shank <NUM> comprises a plurality of spaced apart holes 27a, which allows to screw the first shank <NUM> to the housing <NUM> in different positions such as the first distance a can be adjusted.

As mentioned above the rail <NUM> is H-shaped, wherein the rail <NUM> further comprises a second guiding space 13a, which extends between the first end <NUM> and the second end <NUM> of the rail <NUM> and which second guiding space 13a has a second opening 13b facing the first side <NUM> of the rail <NUM>. The holding device <NUM> further comprises at least one first attachment device <NUM> for attachment of the holding device <NUM> to a surface, preferably the ceiling inside the cargo space of a vehicle. The second guiding space 13a is arranged to accommodate and guide the at least one first attachment device <NUM> when positioning and mounting the first attachment device <NUM> to the ceiling or other interior part to which the rail <NUM> is to be mounted. The at least one first attachment device <NUM> is in turn arranged to be connected to the rail <NUM> in an optionable position along the rail <NUM> by that second means <NUM>, which is arranged into the second guiding space 13a may slide along the rail <NUM> to a position where the fixation of the first attachment device <NUM> is to be performed. In this position, the second means <NUM> of the first attachment device <NUM> is locked to the rail by clamping the first attachment device <NUM> to the second means <NUM> by screws or the like. By that the second attachment device <NUM> is slidable along the rail <NUM>, the positioning of the second attachment device <NUM> is simplified and it is very easy to attach the holding device <NUM> to the substrate (ceiling or rack or the like).

<FIG> is a view of the second holder <NUM> of the holding device <NUM>, seen obliquely from above, and <FIG> and <FIG> shows sections of the second holder <NUM>, seen obliquely from above and from the side. The second holder <NUM> is arranged to hold an end of an item like a ladder, preferably in a position closer to the back doors of a cargo space of a vehicle compared to the position of the first holder <NUM>. As mentioned before, the first holder <NUM> is preferably a front holder and the second holder <NUM> is a back holder for the ladder. The second holder <NUM> is arranged to be fixedly connected at the second side <NUM> of the rail <NUM> in an optionable position along the rail <NUM>, somewhere between the first holder <NUM> and the second end <NUM> of the rail <NUM>. The second holder <NUM> therefore has first means 30a which is arranged to fit into the first guiding space 14a and which means 30a is arranged to slide along the first guiding space 14a of the rail <NUM>. Of course, the first guiding space 14a is arranged to guide the second holder <NUM>/the first means 30a when the second holder <NUM> is moved along the rail <NUM>. The second holder <NUM> further comprises a second locking arrangement <NUM>, which is arranged to lock the second holder <NUM> to the rail <NUM> in a locked state and arranged to unlock the second holder <NUM> in an unlocked state. The second locking arrangement <NUM> preferably is a screw with a handle and the first means 30a of second holder <NUM> preferably is a sliding block with a threaded hole, wherein the screw is in threaded connection with the sliding block. By tightening the screw by rotating the handle clockwise, the sliding block is clamped to the rail <NUM> and the second holder <NUM> is locked to the rail <NUM>. And vice versa, by loosening the screw counterclockwise, the sliding block is released from the clamped position and the second holder <NUM> is unlocked from the rail <NUM>. By that, the second holder <NUM> is slidable along the rail <NUM> and arranged to be locked in any position along the rail <NUM>.

To be able to receive an end of a ladder or an item, the second holder <NUM> comprises a third shank <NUM> which is arranged perpendicular relative the rail <NUM>. At an outer end of the third shank <NUM>, a fourth shank <NUM> is arranged and protrudes in direction towards the first holder <NUM>, substantially perpendicular relative the third shank <NUM>. The fourth shank <NUM> functions as a support for an end of a ladder. To be able to adapt the second holder <NUM> to different ladders or items with different heights, a second distance b between the fourth shank <NUM> and the rail <NUM> is optionable, by that the third shank <NUM> comprises a plurality of spaced apart holes 37a, which allows to screw the first shank <NUM> to an angled bracket 37b, which has corresponding holes, in different positions such as the second distance b can be adjusted. The angled bracket 37b preferably comprises one shank extending along the rail <NUM> and which is positioned between the handle of the second locking arrangement <NUM> and the rail <NUM>, to be able to be clamped to the rail <NUM> while locking the second holder to the rail <NUM> by the second locking arrangement <NUM>. A second shank of the angled bracket 37b preferably is perpendicularly arranged relative the rail <NUM> and thus extending in the same direction as the third shank <NUM> of the second holder <NUM>.

To add the possibility to add extra securing possibilities for fixing the ladder when clamped between the first and second holders <NUM>, <NUM>, the second holder may comprise a strap <NUM>. The strap <NUM> is secured with one end to the angled bracket 37b or the third shank <NUM>, and the other end of the strap <NUM> is removably attached to the third shank <NUM> of the second holder <NUM>. The strap <NUM> may also be adjustable in any known way.

Claim 1:
Holding device (<NUM>) arranged to be mounted to a surface inside a cargo space of a vehicle, the holding device (<NUM>) comprising:
at least one elongate rail (<NUM>) extending between a first end (<NUM>) and a second end (<NUM>), the rail (<NUM>) further comprising a first side (<NUM>) which is arranged to be fixedly attached to said surface, and a second side (<NUM>) which is opposite the first side (<NUM>),
a first holder (<NUM>) movably connected at the second side (<NUM>) of the rail (<NUM>), and arranged to slide along the rail (<NUM>) between the first and second ends (<NUM>, <NUM>) of the rail (<NUM>),
a second holder (<NUM>), arranged to be fixedly connected at the second side (<NUM>) of the rail (<NUM>) in an optionable position along the rail (<NUM>), between the first holder (<NUM>) and one of the first and second ends (<NUM>, <NUM>) of the rail (<NUM>), characterized by that the first holder (<NUM>) comprises a spring (<NUM>) attached with a first end (<NUM>) to the first holder (<NUM>) and attached with a second end (<NUM>) to a mount (<NUM>), which mount (<NUM>) is arranged to be fixedly connected at the second side (<NUM>) of the rail (<NUM>) in an optionable position along the rail (<NUM>), between the first holder (<NUM>) and the second holder (<NUM>), wherein the spring (<NUM>) is a constant force band spring (<NUM>).