Patent Description:
Tall buildings, and ladders for carrying out work at great heights, have existed for centuries. In addition to ladders, scaffolding is also used, especially for carrying out one-off but long-term work on the facade of a building. And to lift heavy loads to a great height, cranes are often used. But ladders remain a very useful means of overcoming relatively small height differences (e.g. from <NUM> to about <NUM>), partly because they are lightweighted and relatively easy to handle. They therefore exist in various embodiments, such as, e.g. as a single ladder, or as extendable ladders (e.g. for the fire brigade), depending on the specific application.

In certain applications such as installing roof coverings (e.g. installing sandwich panels or corrugated sheets) of certain high buildings without intermediary floors, such as a production hall, a warehouse or a barn, work is often not done from the ground or from an intermediary floor, due to the large height difference, and scaffolding is not used because the work is short-term (e.g. less than a week), but work is often done from the roof itself, or at least from a part of the roof that has already been installed. A first part of the roof is then installed first in the classic way (e.g. from the ground), but subsequently, work is done, e.g. laterally from the partially covered roof, by moving ladders on an existing truss or purlins. This may sound simple, but it is certainly not selfevident to displace ladders laterally at a relatively high height (e.g. at a height of <NUM> or <NUM>), especially if several ladders have to be used and/or if a relatively large distance between neighbouring purlins must be bridged. Unfortunately, accidents regularly occur during such work. The present invention seeks a solution to perform such work more safely and/or more efficiently from the roof itself.

<CIT>(A1) describes a ladder system (shown in <FIG>) with a main ladder section <NUM> and a hanging ladder section <NUM> attached to the main ladder section. The ladder system also has a portion <NUM> that hangs over the ridge <NUM> of the roof <NUM>. This system may be useful for carrying out work on an existing roof (such as sweeping a chimney or plugging a leak), but it is not particularly suitable for installing a non-existent roof covering.

Another ladder system for working on a sloping roof is disclosed by <CIT>.

It is an object of the present invention to provide a ladder system for carrying out work on a sloping roof of relatively high buildings, such as, e.g. for installing a roof covering on purlins.

More specifically, it is an object of the present invention to provide a ladder system that is easier to displace.

This goal is achieved by a ladder system according to claim <NUM>.

The present invention provides, in a first aspect, a ladder system comprising: at least a first ladder segment; a motorized displacement mechanism for displacing the ladder system in a longitudinal direction of a ridge of a roof, wherein the displacement mechanism comprises at least one motor; and a control system for controlling the at least one motor of the displacement mechanism. The displacement mechanism comprises a plurality of displacement units, including a first displacement unit attached at the top of the first ladder segment and a second displacement unit attached at the bottom of the first ladder segment. Each displacement unit comprises at least one motor.

An advantage of such a ladder system is that it is extremely suitable for carrying out work from a sloping roof slope, e.g. for installing a roof covering on purlins of high buildings, especially buildings without intermediary floors, such as a production hall, a warehouse or a barn, wherein the distance between the purlins and an underlying surface is large, for example at least <NUM>.

It is an advantage of such a ladder system that it can automatically move along the length of the roof ridge, such that the roofers do not have to exert manpower and perform dangerous manoeuvres to move the ladder system manually, during which they may lose their balance. This allows them to concentrate on their actual work, such as installing and attaching a sloping roof covering. This not only increases efficiency, but also greatly increases safety, and significantly reduces the risk of accidents, such as roofers sliding off the roof.

It is an advantage to use an initial ladder segment, and not e.g. a tub with a full bottom, because a ladder segment is much lighter in weight (with a lot of open space but still sturdy), which greatly simplifies initial positioning of the ladder system on the purlins or on a half-finished roof. The ladder system can be placed onto the roof with a crane, for example by means of a supporting frame. The ladder segments can be joined together on the ground to achieve a desired length of connected ladder segments. The length may be, for example, up to <NUM>, although the present invention is not limited thereto.

It is an advantage to provide at least one displacement unit at the top and at least one displacement unit at the bottom of the first ladder segment, because this makes the displacement of the ladder system more uniform, and reduces bumping, jolting and rocking.

In an embodiment, the ladder system further comprises a hook portion, preferably releasably attachable, e.g. releasably attached, to the first ladder segment, wherein the hook portion has or can assume a shape that can be partially placed over the ridge of the roof; and wherein the hook portion comprises a third displacement unit located on the opposite side of the ridge with respect to the first ladder segment; and wherein the third displacement unit comprises at least one motor; and wherein the control system is further provided for controlling the motor of the third displacement unit for simultaneously displacing the hook portion and the first ladder segment in the longitudinal direction of the ridge. Alternatively, the hook portion can be non-releasably attached to the first ladder segment. The advantage of a releasably attached hook portion is that it can enable displacement of the ladder system in multiple parts (e.g. hook portion and first ladder segment separately). Moreover, the hook portion can then optionally be released in case use of the hook portion is not necessary, or for transport and/or storage. In preferred embodiments, the hook portion forms a basic module from which other parts of the ladder system, such as the displacement mechanism, are controlled. In these embodiments the hook portion is preferably always present in the ladder system.

The hook portion is an optional component of the ladder system. An advantage of the hook portion is that it can be used as a suspension point over the ridge. If the hook portion is present, it can help to reduce the risk of the ladder system sliding down, as it "hooks" onto the other side of the roof, albeit in a movable manner. The latter is an advantage that should not be underestimated, compared to certain state of the art (as shown, e.g. in <FIG>), wherein although a hook portion is used, that hook portion is fixed and therefore not displaceable without a roofer moving to the other side of the roof, temporarily loosening it, causing it to lose its function as all ladders hanging from it would then become loose, again creating a dangerous situation and also causing a lot of time to be lost.

Also, if the ladder is used with many modules, e.g. many ladder segments (for example in the case of roof surfaces with a length, from the gutter to the ridge of the roof, of <NUM> or <NUM>), a lower module, i.e. ladder segment can be equipped with a powered running wheel, typically part of the motorized displacement mechanism, which can be supported in the gutter.

It is therefore a huge advantage of an embodiment of the ladder system when it not only consists of a first ladder segment, but when it also contains the hook portion, whereby the hook portion can also move automatically.

However, it should be noted that the hook portion is not strictly necessary for the present invention to work. After all, the first ladder segment can also be hung on existing purlins. This method of mounting can be used for installing the very first roof coverings, after which the ladder system can be displaced from the purlins to the already constructed roof system, and then gradually displaced laterally until the entire roof surface is covered.

A further advantage of the hook portion is that a roofer can secure himself to it, such that he does not fall from a great height from the roof if he missteps or loses his balance. It is an advantage to secure himself to the hook portion, because the hook portion is displaced over the roof, and a roofer does not have to constantly detach itself from one place and reattach itself to another place.

It is an advantage that the hook portion has its own displacement unit, which results in a smooth displacement, which avoids or at least reduces bumping or swinging displacements.

In an embodiment, the hook portion is tiltably connected to the first ladder segment by means of a motorized tilting mechanism that comprises a first motor; wherein the control system is further provided for controlling the first motor of the tilting mechanism for tilting the hook portion at a first adjustable angle relative to the first ladder segment.

It is an advantage that the hook portion is tiltable, because this allows the roofer to mount the hook portion to the first ladder segment on one sloping side of the roof, and then easily tilt the hook portion over the ridge without physically having to go over the ridge, and without exerting manpower. This again increases efficiency and safety. This same mechanism can also be used to easily release the ladder system during disassembly, by tilting the hook portion back over the ridge (as shown in <FIG> and <FIG>).

In an embodiment, the hook portion comprises two cooperating parts that are tiltably connected to each other, including a first part that is tiltably connected to the first ladder segment at the first adjustable angle, and a second part that is tiltably connected to the first part at a second adjustable angle that can be set independently of the first angle; and wherein the tilting mechanism further comprises a second motor for tilting the second part relative to the first part; and wherein the control system is further provided for controlling the second motor of the tilting mechanism; and wherein the third displacement unit is attached to the second part of the hook portion.

This offers the advantage that the third displacement unit can be positioned easily and optimally for different roof slopes (with different angles).

Alternatively, the hook portion consists of only one part, e.g. one undeformable structure, which is tiltably connected to the first ladder segment at one end, and to which the third displacement unit is attached at the other end.

In an embodiment, the first ladder segment and the hook portion are attachable by means of releasable locking mechanisms such as, e.g. quick couplings or click connections.

In this way, the hook portion can be quickly and safely attached to the first ladder segment when mounting the ladder system, and released again when dismounting the ladder system. The coupling may be a purely mechanical connection.

However, it is an advantage if the coupling is not merely a mechanical coupling, but also an electrical coupling. This can be achieved, for example, by also providing the mechanical coupling with interlocking connectors, for example a male and a female connector. In this way, the motor can be controlled elegantly, with a minimum of cables, which further increases safety because it reduces or eliminates the chance of tripping over the cables.

In an embodiment, the displacement mechanism, e.g., each displacement unit, such as each of the first and second displacement units, comprises a first and a second axle, spaced apart, and operatively connected to the motor of the displacement mechanism, such as to the respective motor of the displacement unit; and a pliable belt disposed abound the first and second axle, the pliable belt being arranged to make mechanical contact with a surface, e.g. a smooth surface or an undulating surface of e.g. a roof covering or purlins; and wherein the motor is provided for rotating the pliable belt abound the first and second axle, such that the ladder system can be displaced in the longitudinal direction of the ridge of the roof.

It is an advantage to make mechanical contact with the load-bearing surface by means of a pliable belt and not with wheels with a fixed axle, because this allows good mechanical contact to be made with both smooth and uneven surfaces, such as, e.g. corrugated sheets or flat surfaces with protruding nuts or bolt heads, or the like.

In embodiments, the travel mechanism comprises a plurality of running wheels for rolling on the inside of the pliable belt - typically against the portion of the pliable belt that travels over a surface, e.g., the roof. In specific embodiments, the running wheels comprise a large wheel portion and a small wheel portion that are rotatable about a central axis of the running wheel, wherein the large wheel portion has a larger diameter than the small wheel portion, and wherein adjacent running wheels are staggered with respect to each other, such that the small wheel portion of a running wheel lies next to the large wheel portion of an adjacent running wheel. The running wheels are typically different from, that is to say additionally on top of, (any wheel present on) the first and second axle.

It is an advantage of these embodiments that the large wheel portion of each running wheel can make rolling contact with the inside of the pliable belt, which can ensure good contact, e.g. a large contact surface, between the running wheels and the pliable belt. This allows the running wheels to keep the pliable belt properly in position. By placing adjacent running wheels staggered, rather than placing the large wheel portions of adjacent running wheels next to each other, more running wheels can make contact with the belt, and the distance, along the longitudinal axis of the displacement unit, between contact points of neighbouring wheels with the pliable belt can be shorter than if the adjacent running wheels were not staggered.

In embodiments, the inside of the pliable belt is grooved or serrated.

It is an advantage of these embodiments that a good coupling can be achieved between the pliable belt and the first and second axle. For example, the first and second axle may each include a roller or cylinder that is grooved or serrated to make good contact with the grooved or serrated interior of the pliable belt. The first and/or second axle can, for example, be a toothed drive wheel.

In an embodiment, the ladder system further comprises at least a second ladder segment, releasably attachable, e.g. attached, to the first ladder segment, wherein the second ladder segment further comprises at least one additional displacement unit (with the at least one additional displacement unit typically being part of the displacement mechanism) ; and wherein the control system is further provided for controlling the at least one additional displacement unit for simultaneously displacing the first ladder segment and the second ladder segment and, if present, also the hook portion, in the longitudinal direction of the ridge.

It is an advantage of the ladder system according to the present invention that it allows a modular construction with multiple ladder segments, as many as necessary. The first ladder segment usually has two displacement units, but more than two is also possible. One or more additional ladder segments can therefore be attached to this. Each additional ladder segment usually has only one displacement unit, namely at the bottom, but it is of course also possible to provide more than one displacement unit. In this way, a very long ladder can be assembled, which can be taken to the roof in separate parts (first segment, optional hook portion, optional second segment, possibly third segment, fourth segment, etc.) and assembled there.

It is an advantage to provide each additional ladder segment with its own displacement unit, because in this way the displacement of the ladder system can take place smoothly and virtually without bumping or pivoting. Naturally, it is also possible to provide one or more intermediate ladder segments that do not have their own displacement unit.

It is an advantage that all segments of the ladder system can be moved simultaneously. In this way, a smooth displacement of the entire ladder system can be achieved. This greatly increases the efficiency of the work, in contrast to existing ladder systems. Where in existing systems with multiple segments, the different segments must be detached, moved and reattached each time, the system of the present invention only needs to be assembled once (i.e. at the start of the works), and only need to be dismounted once (i.e. at the end of the works). This saves a significant amount of time and also drastically reduces the risk of accidents, especially since accidents occur more often when loosening, installing and attaching the ladder segments than during the actual tasks such as attaching a roof covering to purlins.

The ladder segments may comprise handrails (not shown), such as at the bottom and/or on the sides, for a roofer to hold on to. Preferably, a ladder segment has a height, from top to bottom, of <NUM> to <NUM> meters, typically from <NUM> to <NUM> meters. The ladder segment preferably has a width of <NUM> to <NUM> meters, such as from <NUM> to <NUM> meters. The distance between successive cross connections, e.g. rungs, is preferably between <NUM> and <NUM>, such as from <NUM> to <NUM>. This can result in a pleasant walking distance.

In an embodiment, the first ladder segment comprises two elongated profiles, e.g. tubular profiles, arranged parallel to each other at a distance from each other, and mutually connected by means of a plurality, i.e., of at least two, transverse connections, e.g. steps or rungs.

In an embodiment, the at least one motor is an electric motor; and the ladder system also comprises cabling that is largely or completely incorporated into the tube profiles. Preferably, all motors are electric motors.

It is an advantage of these embodiments that the profiles not only provide mechanical strength, but also electrical connection through the tube profiles, although this is not strictly necessary. The electrical connection between two separate segments can then be made, for example, through cooperating connectors (male-female), or, e.g., by connecting a short cable at the top end of the second segment with a contact at the bottom of the first segment, or vice versa.

It is an advantage to integrate the cables into the tube profiles, because this avoids loose cables, which reduces the risk of tripping, which improves safety.

In an embodiment, the ladder system further comprises at least one battery for supplying energy to the at least one motor, such as each motor, and to the control system.

The ladder system can be powered from the ground with a cable or by means of one or more batteries. Such batteries can be placed on the ladder system, or can also be placed next to the ladder system on the roof. When batteries are used, there is no need to run a cable to the ground, which further simplifies moving the ladder system.

In an embodiment, the ladder system further comprises a wireless control for wirelessly controlling the control system.

It is an advantage that the ladder system can be operated from the ladder itself. To this end, the ladder system can contain multiple push buttons, e.g. attached, built-in or built-on in the first ladder segment. Optionally, such push buttons can also be provided on one or more other ladder segments. Alternatively or in combination therewith, the control system includes a wireless receiver, provided to receive commands from an associated wireless transmitter, which may be worn by the roofer. An advantage of wireless control is that it offers much more freedom of movement to the roofer, who does not have to go to one specific place to press a button.

In a second aspect, the present invention provides a use of the ladder system according to embodiments of the first aspect, and according to claim <NUM>, for working on a roof, for example for installing or removing roof covering, whether or not in the form of panels.

Specific and preferred aspects of the invention are included in the appended independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as expressly set out in the claims, but within the scope defined by the independent claims.

These and other aspects of the invention will be apparent and elucidated with reference to the embodiment(s) described below.

The figures are only schematic and not limiting. In the figures, the dimensions of some parts may be exaggerated and not to scale for illustrative purposes. The dimensions and relative dimensions sometimes do not correspond to the actual practical embodiment of the invention.

Reference numerals in the claims should not be interpreted to limit the scope of protection.

In the different figures, the same reference numerals refer to the same or similar elements.

The present invention will be described with reference to particular embodiments and with reference to certain drawings, but the invention is not limited thereto but is limited only by the claims.

It should be noted that the term "comprise", as used in the claims, is not to be construed as limited to the means described thereafter; this term does not exclude other elements or steps. It can therefore be interpreted as specifying the presence of the stated characteristics, values, steps or components referred to, but does not exclude the presence or addition of one or more other characteristics, values, steps or components, or groups thereof. It means that with regard to the present invention, A and B are the only relevant components of the device.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a specific feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, occurrences of the phrases "in one embodiment" or "in an embodiment" at various places throughout this specification do not necessarily all refer to the same embodiment, but may do so. Furthermore, the specific features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art, based on this disclosure, in one or more embodiments.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure or description thereof for the purpose of streamlining disclosure and aiding in the understanding of one or more of the various inventive aspects. In any case, this method of disclosure should not be interpreted as reflecting an intention that the invention requires more features than those explicitly stated in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all the features of a single previously disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing alone as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some, but not other, features included in other embodiments, combinations of features of different embodiments are intended to be within the scope of the invention as defined by the claims, and constitute different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the described embodiments may be used in any combination.

The present invention provides a ladder system <NUM>, more specifically a motorized ladder system that can be displaced in the longitudinal direction of the ridge <NUM> of a roof <NUM>. This system offers a solution for carrying out certain work on roofs more safely and efficiently, such as installing the roof covering, e.g. corrugated sheets, panels, sandwich panels, etc. of high buildings (e.g. at least <NUM>, or at least <NUM>, or at least <NUM> above the ground or above a floor), e.g. industrial buildings without intermediary floors, a production hall, a warehouse or barn or the like from the roof itself, hence without using a ladder that rests with one end on the ground or on a intermediary floor.

<FIG> shows a ladder system from the state of the art. This ladder system has already been discussed in the background section, but does not offer a good solution to the problem described above, e.g. for installing a roof covering when there are only purlins <NUM> (see <FIG>).

<FIG> shows an example of a ladder system <NUM> according to the present invention, in perspective top view. This ladder system <NUM> has a first ladder segment <NUM>, a second ladder segment <NUM>, a hook portion <NUM>, and a control system (not shown), but the second ladder segment <NUM> and the hook portion <NUM> are not necessary to obtain the benefits of the present invention.

It is essential that the ladder system <NUM> has a first ladder segment <NUM>, and a motorized displacement mechanism for displacing the ladder system <NUM> in a longitudinal direction X of the ridge <NUM> of the roof <NUM>. The displacement mechanism comprises at least a first displacement unit <NUM> (see <FIG>) attached at the top of the first ladder segment <NUM>, and a second moving unit <NUM> which is attached at the bottom of the first ladder segment <NUM>. In the example of <FIG>, there is an additional displacement unit <NUM> at the bottom of the second ladder segment <NUM>, as well as a third displacement unit <NUM> attached to the hook portion <NUM>, but as already mentioned, both the second ladder segment <NUM> and the hook portion <NUM> are not necessary, and in that case, the third and additional displacement units <NUM> and <NUM> will not be present.

Each displacement unit, i.e. the first and second displacement units <NUM>, <NUM>, and, if present, also the third and additional displacement units <NUM>, <NUM>, contains its own motor <NUM>. The ladder system further contains a control system (not shown) for controlling the motors. Motor controls are known in the state of the art and therefore do not need to be explained further.

Such a ladder system <NUM> is extremely suitable for carrying out work on a sloping roof slope, e.g. for installing a roof covering on purlins of high buildings, especially buildings without intermediary floors, such as a production hall, a warehouse or a barn, wherein a distance between the purlins and an underlying floor is at least <NUM>.

The ladder system <NUM> can automatically advance in the direction X of the roof ridge <NUM>, eliminating the need for roofers to exert manpower to displace the ladder system. The ladder system therefore allows the roofers to concentrate on their actual work, such as, e.g. installing and attaching a roof covering. In this way, the efficiency of the work is increased and the risk of accidents is reduced.

The ladder system shown in <FIG> comprises a hook portion <NUM> that is attached to the first ladder segment <NUM>. The hook portion can be placed partially over the ridge <NUM> of the roof. The hook portion <NUM> can be used as a suspension point, and can therefore contribute to reducing the risk that the ladder system <NUM> may slide down. Although a ladder system is known in the state of the art where a hook portion is also used (see <FIG>), this ladder system is fixed to the roof, and therefore differs from the solution offered by the present invention.

It is an advantage of the present invention that should not be underestimated that the ladder system can automatically move in the longitudinal direction of the ridge, even if a hook portion is used, thanks to the fact that the hook portion also has a displacement unit. As a result, the hook portion <NUM>, if present, will automatically move along with the rest of the ladder system <NUM>.

<FIG> show the ladder system <NUM> of <FIG>, but at a later time, after the hook portion <NUM> has been partially tilted towards the first ladder segment <NUM>. The hook portion <NUM> shown can be tilted in its entirety with respect to the first ladder segment <NUM> by means of a tilting mechanism, preferably a motorized tilting mechanism, but a manual tilting mechanism will also work. The motor <NUM> (see <FIG>) of such a motorized tilting mechanism can then also be controlled by the control system. The tilting mechanism allows the hook portion <NUM> to be easily displaced over the ridge <NUM>, without the roofer having to exert manpower or perform dangerous manoeuvres.

<FIG> show the ladder system <NUM> of <FIG> in side view, in different positions of the hook portion <NUM>. The hook portion <NUM> may consist of one rigid (albeit angular) structure, or of two parts <NUM>, <NUM> that can be tilted relative to each other to form an angle β. The angle α between the first part <NUM> and the first ladder segment <NUM> and, if the hook portion consists of two tiltable parts, also the angle β between the first part <NUM> and the second part <NUM>, can be adjusted independently of each other. This allows, among other things, that the displacement unit <NUM> can be positioned simply and optimally, depending on the angle of the roof slope. The tilt mechanism for adjusting the angle β can be manually operated or motorized. In the latter case, this motor <NUM> (see <FIG>) is also preferably controlled by the control system.

Although the displacement units can travel over the purlins <NUM>, it is preferably also possible not to let the displacement units <NUM>, <NUM>, <NUM> travel over the purlins <NUM>, since screws must be applied to the purlins <NUM>, for example to screw down or unscrew roof panels. After all, if the displacement units <NUM>, <NUM>, <NUM> lie on the purlin, they are in the way. The ladder system <NUM> can travel on an installed roof panel, and a subsequent roof panel, for example from the ladder system <NUM>, can be placed into position. The ladder system <NUM> then moves onto the next installed roof panel, with the displacement units <NUM>, <NUM>, <NUM> away from the purlins <NUM>, and the roofer <NUM> can simply screw down the next installed roof panel to the purlin. To achieve this, per ladder segment <NUM>, the displacement unit <NUM> can be displaceable along the longitudinal axis of the ladder segment <NUM>. For the third displacement unit <NUM>, which may travel over a purlin that does not require screwing, this is probably less important.

<FIG> is an enlarged side view of an upper portion of the first ladder segment <NUM> and of the hook portion <NUM> of the ladder system of <FIG>.

A person, e.g. roofer <NUM>, is also drawn, standing on one of the rungs or steps of the first ladder segment <NUM>. The roofer <NUM> preferably places the toes on the roof and the heels on the rung(s), which can result in good stability of the person on the ladder system. (It should be noted that this is only a computer drawing that schematically represents the roofer <NUM> and the ladder system: in practice, the person will typically adopt a different, more stable, position, for example bent over to perform his work).

Also visible is the first displacement unit <NUM> with motor 114a and pliable belt 118a, e.g. rubber belt.

The shown hook portion <NUM> consists of two parts: a first part <NUM> and a second part <NUM>. The first part <NUM> is tiltably connected to the first ladder segment <NUM>, and defines a first angle α (see <FIG>). The second part <NUM> is tiltably connected to the first part <NUM> and defines a second angle β (see <FIG>). The first and second angle α, β can be adjusted independently of each other. In the example, both tilting mechanisms are motorized, by motor <NUM> and <NUM>. On the second part <NUM>, there is a third displacement unit <NUM>, with motor 114c and pliable belt 118c, e.g. a rubber belt. The motors are controlled together by a control system (not shown) to move the ladder system <NUM> as a whole in the longitudinal direction of the ridge <NUM> (perpendicular to the drawing).

In an alternative embodiment, the hook portion <NUM> consists of one rigid structure (not shown) that is completely tiltable relative to the first ladder segment <NUM>.

In an alternative embodiment, the tilting mechanism or mechanisms are not motorized, but can be operated manually.

<FIG> is a perspective view of the same portion of the ladder system <NUM> as shown in <FIG>.

The ladder segments are preferably constructed from two tube profiles, e.g. tube profiles with a square or rectangular cross-section. Such profiles require less material, are therefore lighter, and are still very sturdy. But other profiles can also be used, e.g. U-profiles, T-profiles, L-profiles, I-profiles, etc..

The tube profiles are interconnected by a plurality of so-called "rungs" <NUM>, but alternatively, steps can also be used. The rungs can also consist of a tubular material, and preferably have a surface that is not smooth, e.g. a ribbed profile, or a groove in which a rubber strip is glued, or the like. This strengthens the grip between the roofer and the ladder system, and reduces the risk of slipping, especially in damp or wet weather conditions.

The material of the two tube profiles is preferably aluminium or an aluminium alloy, because this can greatly reduce the weight. A suitable alloy can be chosen, depending on the required tensile or bending strength.

Preferably, all motors <NUM> are electric motors, and the cabling of the control system (not shown) and the power supply (not shown) is concealed as much as possible in the profiles, to reduce or eliminate the risk of tripping.

<FIG> show a possible embodiment of the displacement units comprising a first axle and a second axle, or a first roller or cylinder and a second roller or cylinder, arranged at a distance from each other, and operationally connected to a motor <NUM> of the displacement unit. About the first and second axle (or roller or cylinder) a pliable belt is arranged, e.g. a rubber belt, that rotates around the first and second axle, e.g. like a conveyor belt or a caterpillar track. The belt can be a rubber belt, to provide better friction or grip with the contact surface. The belt is designed to make good mechanical contact with the surface on which it rests, e.g. with a smooth surface (e.g. sandwich panels) but also with a wavy surface (e.g. corrugated sheets) of a roof covering or with a surface of purlins <NUM> (e.g. wooden beams, or steel pipes or the like). The motor <NUM> rotates the belt <NUM> about the first and second axle, allowing the ladder system <NUM> to move in the longitudinal direction of the ridge <NUM> of the roof.

A compressible cylinder made of, for example, a foam material can be placed between the pliable belt and the axle. By using a pliable belt and not just rigid wheels, good mechanical contact can be made, both with smooth and uneven surfaces, e.g. surfaces with protruding nuts and/or bolts, or the like.

Although not shown, the person may hand-hold a multi-button command box with a cable connected to the first ladder segment to operate the ladder system <NUM>. Alternatively, he may use a wireless remote control.

<FIG> is another perspective view of the ladder system of <FIG>, without the roofer. In these figures, the first ladder segment <NUM> is shown in full, as well as an upper part of the second ladder segment <NUM>. In this figure, both the first displacement unit <NUM> with motor 114a and belt 118a, at the top of the first ladder segment <NUM>, as well as the second displacement unit with motor 114c and belt 118b at the bottom of the first ladder segment <NUM>, are shown. The third displacement unit of the hook portion <NUM> with motor 114c and belt 118c is also shown. The use of multiple displacement units ensures smooth displacement of the ladder system <NUM>, especially when it has a large length (e.g. <NUM> or even more).

<FIG> is yet another perspective view of the ladder system of <FIG> and <FIG>, again without the roofer, and also shows the second ladder segment <NUM> in full, including the additional displacement unit at the bottom of the second ladder segment, with motor 114d and belt 118d. This motor is also controlled by the control system (not shown).

Although not shown in detail, the first ladder segment <NUM> and the hook portion <NUM>, as well as the first ladder segment <NUM> and the second ladder segment <NUM>, are attached to each other by means of releasable locking mechanisms, such as e.g. quick couplings or click connections.

In this way, the various, albeit optional, parts can be quickly and safely attached to the first ladder segment <NUM> when mounting the ladder system <NUM>, and quickly released again when dismounting the ladder system. The coupling, e.g. click connection, can be a purely mechanical connection, or can also be an electrical coupling, e.g. using an optionally built-in male and a female connector (not shown). Such coupling are known per se in the state of the art and therefore do not need to be described in detail.

In the illustrated examples, the ladder segments are always positioned in close proximity to the roof surface. However, this is not a requirement. In embodiments of the present invention, the displacement unit is made higher or thicker, such that the ladder system is still displaceable over the roof surface, but at a greater distance from it. This can be useful, for example, for cleaning solar panels, installed on roofs. By moving the ladder segments higher up (at a greater distance from the roof surface), they can move over the solar panels, thus allowing operations on the solar panels without damaging them.

<FIG> shows how the first ladder segment can be suspended from purlins <NUM>, and can be displaced relative to these purlins, in the longitudinal direction X of the ridge <NUM> of the roof (perpendicular to the plane of the figure). Only the first ladder segment <NUM> is shown, with a first displacement unit of which only a suspension wheel <NUM> and a first pliable belt 118a are shown. The first displacement unit is located at the top of the first ladder segment. Also shown is a second displacement unit of which also only a suspension wheel <NUM> and a pliable one belt 118b is shown. The second displacement unit is attached to the bottom of the first ladder segment <NUM>. The suspension wheels <NUM>, <NUM> are optional, but are preferably attached to the first ladder segment in a tiltable manner. This tilting can, but does not have to, be motorized. In some embodiments, the suspension wheels <NUM> and <NUM> can even be omitted completely, for example when the ladder system is not installed on the purlins <NUM>, but only on a part of the roof that has already been constructed.

<FIG> shows a displacement unit <NUM> according to embodiments of the ladder system of the present invention. A pliable belt <NUM>, in this example a toothed belt, is arranged around a first axle <NUM> and a second axle <NUM>. The first axle <NUM> and the second axle <NUM> are rotatably fixed to a frame <NUM> of the displacement unit <NUM>. For driving the displacement unit <NUM>, in this example, a first gear <NUM> is mounted on the first axle <NUM>, which can be coupled, for example via a chain (not shown), to a second gear <NUM>, which can be operationally connected to an output axle of a motor (not shown). The first axle <NUM> and the second axle <NUM> contain, in this example, a corrugated cylinder for turning against an inside of the pliable belt <NUM>, such that a good grip of the axles on the toothed belt, i.e., the pliable belt <NUM>, can be achieved. The first axle <NUM> can be a toothed drive wheel for driving the pliable belt <NUM>.

<FIG> shows an enlarged view of the part of the displacement unit <NUM> within the square with dotted line in <FIG>. The second axle <NUM> is, in this example, received in a notch <NUM> of the frame <NUM> of the displacement unit <NUM>. The second axle <NUM> can, in this example, be held in position in the notch <NUM> with a bolt <NUM> comprising a head, suitable for rotatably fixing the second axle <NUM>, and nuts <NUM>, secured to a projecting element <NUM> of the frame <NUM>, wherein the protruding element <NUM> comprises a hole to receive the bolt <NUM>. The displacement unit <NUM>, in this example, mirrored on the other (not shown) side, contains similar elements to keep the second axle <NUM> rotatably in position at two ends. By turning the nuts <NUM>, the second axle <NUM> can be slid along the longitudinal axis of the displacement unit <NUM> through the notch <NUM>, such that the pliable belt <NUM> can be tensioned.

For further explanation, reference is made to <FIG>. A first coupling piece <NUM> and a second coupling piece <NUM> are further provided on the frame <NUM> of the displacement unit <NUM>. The elongated profiles of a ladder segment can be connected to the displacement unit <NUM> via these coupling pieces <NUM> and <NUM>.

The displacement unit <NUM> of this example further comprises a plurality of running wheels <NUM> along the longitudinal axis of the displacement unit <NUM>. These running wheels <NUM> roll on the inside of the pliable belt <NUM>, in this example against the lower part of the pliable belt <NUM>, which is in a position to contact a surface, for example a roof. These running wheels <NUM> keep the pliable belt <NUM> in position between the first axle <NUM> and the second axle <NUM>, such that the pliable belt <NUM> may bend only slightly, for example when driving over an uneven surface, and a good coupling can be maintained between the pliable belt <NUM> and the surface over which the displacement unit <NUM> travels.

<FIG> is a schematic top view of an embodiment of the running wheels <NUM>, wherein four running wheels <NUM> are shown. Preferably, the displacement unit <NUM> comprises at least ten, such as at least twenty, running wheels <NUM>. The running wheel <NUM> has a large wheel portion <NUM> and a small wheel portion <NUM>, both of which rotate about a central axis <NUM> of each running wheel <NUM> (shown, for one of the running wheels, by the dotted line), wherein the large wheel portion <NUM> has a larger diameter than the small wheel portion <NUM>, and wherein the large wheel portion <NUM> and the small wheel portion <NUM> are connected to each other or are made in one piece. Adjacent running wheels <NUM> and <NUM>, e.g. a first running wheel <NUM> and a second running wheel <NUM>, are staggered with respect to each other, i.e. the large wheel portion of a first running wheel <NUM> lies next to the small wheel portion of a second, adjacent running wheel <NUM>, and vice versa. By staggering the running wheels <NUM>, a running wheel with a large diameter (i.e. the diameter of the large wheel portion <NUM>) can be used, such that good contact can be achieved between the running wheels <NUM> and the pliable belt. In this case, the distance, in the direction of the longitudinal axis of the displacement unit <NUM>, between contact points of adjacent running wheels <NUM> with the pliable belt, e.g. between the contact point of the first running wheel <NUM> with the pliable belt and the contact point of the second running wheel <NUM> with the pliable belt, is smaller in this staggered configuration than if the running wheels <NUM> were placed in a non- staggered way.

<FIG> show, in perspective view and side view respectively, a roof <NUM> with thereon a first displacement unit <NUM>, a second displacement unit <NUM> and a third displacement unit <NUM> of a ladder system according to embodiments of the present invention. The elongated profiles of a ladder segment (not shown) can be secured in the first coupling pieces <NUM> and <NUM> of the first and second displacement unit <NUM> and <NUM>. The third displacement unit <NUM> is, in this example, part of a hook portion.

Strictly theoretically, each displacement unit <NUM>, <NUM>, <NUM> could be placed parallel to the ridge <NUM>. However, when displacing (driving) the displacement unit <NUM>, <NUM>, <NUM> over the roof, a considerable force acts upon the displacement unit, as a result of which it tends not to travel nicely parallel to the ridge, but slightly diagonally downwards. To counteract this, each displacement unit <NUM>, <NUM> and <NUM> is preferably oriented in such a way that it faces in the direction of the ridge <NUM> of the roof <NUM>. Because the displacement unit <NUM>, <NUM> and <NUM> is guided slightly upwards, the displacement unit <NUM>, <NUM> and <NUM> can, under the influence of the other forces acting on it, perform a resulting horizontal displacement parallel to the longitudinal direction of the cam <NUM>, wherein a downward displacement, as a result of the force of gravity acting on the displacement unit <NUM>, <NUM> and <NUM>, can be corrected.

Claim 1:
A ladder system (<NUM>), comprising:
- at least a first ladder segment (<NUM>);
- a motorized displacement mechanism for displacing the ladder system (<NUM>) in a longitudinal direction (X) of a ridge (<NUM>) of a roof (<NUM>), wherein the displacement mechanism comprises at least one motor (114a, 114b); and
- a control system for controlling the at least one motor (114a, 114b) of the displacement mechanism,
wherein the displacement mechanism comprises a plurality of displacement units (<NUM>, <NUM>), including a first displacement unit (<NUM>) attached at the top of the first ladder segment (<NUM>) and a second displacement unit (<NUM>) attached at the bottom of the first ladder segment (<NUM>), wherein each displacement unit (<NUM>, <NUM>) comprises at least one motor (114a, 114b).