PLATFORM LADDER APPARATUS

Abstract

A platform ladder apparatus (2) has a transport position and a use position in which the apparatus is arranged to lean against a wall (W) for performing work at an elevated level. The apparatus (2) has a ladder (4) and a working platform (20). A proximal side of the platform is pivotally connected at an upper end of the ladder such that it may be pivoted towards the ladder (4) to a stowed position essentially parallel to the ladder (4). The apparatus further comprises a pair of wall support arms (80) for stabilizing the apparatus in the use position in relation to the wall. The wall support arms (80) are connected to the platform (20) for movement between a stowed arm position in which the arms (80) project out from a distal side (24) of the platform (20) thereby preventing use of the apparatus, and a stabilizing arm position in which the arms (80) project sideways from the platform (20) in opposite lateral directions, respectively, for stabilizing the apparatus (2) in relation to the wall (W).

Claims

1. A platform ladder apparatus (2) having a transport position and a use position in which the apparatus is arranged to lean against a wall (W) for performing work at an elevated level, said apparatus (2) comprising: a ladder (4) having a front side for climbing and a rear side facing the wall (W) in the use position; a working platform (20) having, seen from the front side of the ladder (4), a right side, a left side, a proximal side and an opposite distal side, the proximal side of the platform being pivotally connected to the ladder at a platform pivot axis (A1) located at an upper end of the ladder, the platform (20) being arranged, in the use position of the apparatus, to extend essentially horizontally out from the ladder (4) with its distal side (24) directed towards the wall (W), and the platform (20) being arranged, in the transport position of the apparatus (2), to be pivoted about the platform pivot axis (A) towards the ladder (4) to a stowed position essentially parallel to the ladder (4); and a right and a left wall support arm (80) for stabilizing the apparatus in the use position in relation to the wall, said wall support arms (80) being connected to the platform (20) for movement between: a stowed arm position in which the wall support arms (80) project out from the distal side (24) of the platform (20) thereby preventing use of the apparatus, and a stabilizing arm position in which the wall support arms (80) project sideways from the platform (20) in opposite right and left directions, respectively, for stabilizing the apparatus (2) in relation to the wall (W).

2. The apparatus according to claim 1, wherein the wall support arms (80) are aligned with each other when in their stabilizing arm position.

3. The apparatus according to claim 1 or 2, wherein the wall support arms (80), when in their stowed arm position, project out from the distal side of the platform essentially along a direction perpendicular to the platform pivot axis (A1).

4. The apparatus according to any of claims 1 to 3, wherein said wall support arms (80) are rotatably connected to the platform (20) at the distal side (24) thereof for rotational movement in a plane parallel to the platform (20) between said stowed arm position and said stabilizing arm position.

5. The apparatus according to claim 4, further comprising arm engaging means (84, 86) which are structured and arranged to engage the wall support arms (80) in their stabilizing arm position to restrict any further rotational movement of the wall support arms (80) beyond the stabilizing arm position, when the wall support arms (80) are being rotated from their stowed arm position into their stabilizing arm position.

6. The apparatus according to claim 5, wherein the right and left wall support arms (80) are rotatably connected to the platform (20) at an associated right and left rotational axis (A3), respectively, extending at right angles to the platform (20) at the distal side (24) thereof; wherein the rotational axis (A3) of each wall support arm (80) is located between an outer end and an inner end of the wall support arm (80), thereby dividing the wall support arm (80) into an outer arm portion and an inner arm portion, and wherein said arm engaging means (84, 86) comprise a right-side and a left-side stop means (86) engaging the outer arm portion of the right and left wall support arm, respectively, in the stabilizing arm position, and/or a central stop means (84) engaging the inner arm portions of the right and left wall support arm (80) in the stabilizing arm position.

7. The apparatus according to claim 5 or 6, wherein the arm engaging means (84, 86) are also structured and arranged, in the stabilizing arm position, to engage the wall support arms (80) to prevent movement of the wall support arms (80) in relation to the platform (20) in a direction perpendicular to the platform (20).

8. The apparatus according to any of the preceding claims, wherein each wall support arm (80) is provided with a wheel or roller (88) at an outer end of the arm (80) for engaging the wall (W) in the use position of the apparatus.

9. The apparatus according to claim 8, wherein said wheels (88) at the outer ends of the wall support arms (80) are arranged rotate in a first direction against the wall (W) when the apparatus (2) is raised into its use position against the wall (W) but blocked or at least braked from rotating in an opposite second direction in order to prevent unintentional lowering of the platform (20).

10. The apparatus according to any of the preceding claims, wherein the ladder (4) is an extension ladder comprising a lower ladder section (10) and an upper ladder section (12) each having a front side and a rear side, the upper ladder section (12) being slidably arranged on the front side of the lower ladder section (10); and wherein the proximal side (22) of the platform (20) being pivotally connected to the upper ladder section (12) at said platform pivot axis (A1) via one or more brackets (21) extending between the platform (20) and the platform pivot axis (A1) for creating a distance (D) between the platform (20) and the platform pivot axis (A1) which is sufficient to allow the platform (20), in the transport position of the apparatus (2), to be folded over the lower ladder section (10) such that the lower ladder section (10) in the transport position of the apparatus (2) is located between the rear side of the upper ladder section (12) and the folded platform (20).

11. The apparatus according to any of the preceding claims, further comprising a foldable user safety railing (40) which in the use position of the apparatus (2) is unfolded and arranged above the working platform (20) for forming a protection for a user standing upon the platform (20), said safety railing (40) comprising right and left proximal posts (42) arranged at the proximal side (22) of the platform (20), right and left distal posts (44) arranged further towards the distal side (24) of the platform (20), and guard rails (46, 47, 49) extending between the posts (42, 44), said safety railing (40) being structured and arranged to be folded into a stowed position in the transport position of the apparatus (2).

12. The apparatus according to claim 11, wherein, in the use position of the apparatus (2), each one of the proximal posts (42) has an upper part which is located above the platform (20) and a lower part which is located under the platform (20) and which is pivotally connected below the platform for pivotal movement about the platform pivot axis (A1), and wherein the user safety railing (40) comprises a load transferring rail member (47) extending between the upper parts of the proximal posts 42.

13. The apparatus according to claim 12, wherein said guard rails comprises a pair of upper side guide rails (46) extending between the proximal posts (42) and the distal posts (44), wherein a distal end of said upper side guide rails (46), in the use position of the apparatus, are located at a distance (a) from the wall (W), and wherein said distance (a) is reduced to zero if and as a result of the lower end of the ladder (4) should accidently slide on the ground way from the wall (W), whereby the upper side guide rails (46) will counteract further sliding by frictional forces in relation to the wall (W).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The inventive concept, some non-limiting embodiments and further advantages of the inventive concept will now be further described with reference to the drawings in which:

[0040] FIG. 1 shows a first embodiment of a platform ladder apparatus according to the invention, showing the apparatus in its use position.

[0041] FIGS. 2A-2B are enlarged perspective views of a platform assembly of the apparatus in FIG. 1.

[0042] FIGS. 3A-3C are a top view, a side view and a front view of the apparatus in FIG. 1 in its use position.

[0043] FIGS. 4A-4B show the apparatus in FIG. 1 with the platform assembly in a partly folded position.

[0044] FIGS. 5A-5B show the apparatus in FIG. 1 in an unfolded position illustrating fail-proof stability features of the apparatus.

[0045] FIGS. 6A-6E show the apparatus in FIG. 1 in its folded transport position.

[0046] FIG. 7 shows the platform ladder apparatus in FIG. 1 with second alternative design of a ground stabilizing assembly.

[0047] FIG. 8 shows the platform ladder apparatus in FIG. 1 with third alternative design of a ground stabilizing assembly.

[0048] FIG. 9 shows a second embodiment of a platform ladder apparatus according to the invention, showing the apparatus in its use position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] FIG. 1 illustrates a platform ladder apparatus 2 according to a first embodiment of the present invention, comprising a ladder 4 and a foldable platform assembly 6. The platform assembly 6, which includes at least a working platform 20 and a safety railing 40 arranged at the perimeter of the platform, is pivotally connected to an upper end of the ladder 4 as will be described in detail below. The apparatus 2 is shown in it its use position in FIGS. 1 to 3, in which the foldable platform assembly 6 is shown it its unfolded, essentially horizontal use position, arranged at an upper end of the ladder 4. The apparatus 2 is shown in its transport position in FIG. 6 and in a partly folded position in FIG. 4.

[0050] As indicated in FIG. 1, the platform ladder apparatus 2 may optionally also comprise transport wheels 50 and a foldable ground support assembly 70.

[0051] The apparatus would normally be manufactured mainly from alumina. However, other materials such as plastic or wood are also conceivable.

[0052] The ladder 4 may be a telescopic ladder (also termed extension ladder) as illustrated in FIG. 1 comprising a lower ladder section 10 and an upper extractable ladder section 12 (fly section), each ladder section 10, 12 comprising a number or rungs or steps 14 extending between a pair of rails. As known in the art, the ladder sections 10, 12 may be slidably connected to each other by external guide brackets 16, such that the ladder sections 10, 12 can be slid together for transport and storage or slid apart with an overlap to expand the length of the ladder 4 in the use position of the apparatus 2. The ladder sections 10, 12 may be held or locked in their expanded position in different ways as known in the art, such as by hooks 18 and/or lock assemblies. The ladder 4 may optionally be provided with pulley-rope means or the like (not shown) to be operated by a user for performing the ladder extraction/retraction. As an alternative, the ladder 4 may also be a straight ladder built in one section.

[0053] In FIGS. 1-3, the apparatus 2 is shown in its use position standing on a ground G and leaning by an angle against a wall W or a surface, with a front or climbing side of the ladder 4 facing away from the wall W and a rear side of the ladder 4 facing towards the wall W, as illustrated in FIG. 3B.

[0054] As shown in enlarged scale in FIGS. 2A and 2B, the platform assembly 6 comprises a working platform 20 defining a floor for a user working on an elevated level and safety railing 40 providing a safety barrier for the user standing or working upon the platform 20. In the use position of the apparatus 2, the platform 20 would normally be essentially horizontal although a minor angle also would be possible.

[0055] The working platform 20 may have a rectangular shape as in the present embodiment, although other shapes are possible, such as square shape, partly rounded shapes and all rounded shapes. The platform 20 presents, when viewed by a person standing on the climbing side of the ladder 4 in the use position of the apparatus 2 and facing the wall, a proximal side 22, an opposite distal side 24 and right and left sides 26, 28.

[0056] As illustrated in this embodiment, the platform 20 may be provided with a upright safety border 29 along its proximal side 22 and along its right and left sides 26, 28.

[0057] The platform 20 is pivotally connected to the upper end of the ladder 4, in this embodiment the upper end of the upper ladder section 10, for pivotal movement in relation to the ladder 4 about a platform pivot axis A1 which is parallel to the rungs 14. As illustrated in this embodiment, this pivotally connection may be implemented by a tube 13, a solid axle or solid tube arranged at the proximal side 22 of the platform 20.

[0058] In a preferred embodiment, the platform pivot axis A1 is located at a distance D from the bottom side of the platform 20, as indicated for instance in FIGS. 2A and 4A. This distance D may serve dual purposes or advantages as will be explained below. The distance D may be implemented by one or more pivot brackets 21 arranged on the bottom side of the platform 20 at the proximal side 22 thereof. In the embodiment shown, the tube 13 extends through openings in a pair of such pivot brackets 21 while the upper ends of the pair of rails of the upper ladder section 12 are pivotally connected to the tube 13 on the outer right and left sides of the pivot brackets 21.

[0059] A first advantage obtained by arranging the platform pivot axis A1 at the distance D from the platform 20 relates to the operation of folding the apparatus 2 into its transport position. As best shown in FIG. 4A (partly folded position) and in FIGS. 6C and 6D (folded position), the distance D is sufficient to allow the platform 20 to be folded over the lower ladder section 10 of the retracted ladder 4 in the stowed transport position of the apparatus 2, such that the lower ladder section 10 in the transport position is located between the rear side of the upper ladder section 12 and the folded platform 20, resulting in very compact dimensions of the apparatus in its transport position.

[0060] A second advantage obtained by arranging the pivot axis at a distance D from the platform 20 relates to the stability of the protective guard or safety railing 40 as will be described in detail below.

[0061] The apparatus 2 may further comprise a pair of struts 30 for maintaining the platform 20 in the desired angle (horizontally) in relation to the ladder 4 in the use position of the apparatus 2. As illustrated in FIG. 1, each strut 30 has a lower end connected to the ladder 4 and an upper end connected to the platform 20. These connections may be pivotally connections.

[0062] In the illustrated embodiment, the upper connection of the struts 30 to the platform 20 is implemented by a pair of downwardly projecting brackets 32 (see FIG. 2B) defining a second pivot axis A2 at a distance below the platform 20. The upper end of each strut 30 is pivotally connected to an associated pivot bracket 32 by a pivot member 34. The lower pivotally connection of the struts 30 to the ladder 4 is implemented by a pair of brackets 36 attached to the upper ladder section 12. In the illustrated embodiment, this lower connection of the struts 30 to the ladder 4 is releasable connection, such that the user may connect the struts to the ladder in the use position and disconnect the struts 30 from the ladder 4 for folding the apparatus into the transport position. The disconnected struts 30 are illustrated in FIGS. 4A and 4B (partly folded position) and in FIGS. 6A-6E (transport position). The releasable connection of the struts 30 to the brackets 36 may be implemented by removable pins 38 or by some other means.

[0063] The safety railing 40 of the foldable platform assembly 6 according to the embodiment shown in FIG. 1 will now be described with reference to the use position of the apparatus 2. The safety railing 40 may be arranged along the perimeter of the platform 20 and comprises a pair of proximal posts 42 which may be arranged at the proximal right and left corners of the platform 20 and a pair of distal posts 44 which may be arranged as illustrated further towards the distal side 24 of the platform 20 at the right and left platform sides, respectively. The posts 42, 44 would normally be essentially vertical in the use position. A lower end of each proximal post 42 is pivotally connected to the tube 13 at the distance D from the platform 20, for pivotal movement about the proximal pivot axis A1. Similarly, a lower end of each distal post 44 is pivotally connected to an associated one of the pivot members 34 held by the brackets 32 for pivotal movement about the distal pivot axis A2.

[0064] In some embodiments, the distal posts 44 may be arranged at the distal corners of the platform 20. However, it may be preferred to arrange the distal posts 44 at a certain horizontal distance from the distal corners of the platform 20 as illustrated in FIGS. 2A and 2B. This will create an advantageous work space between the posts 44 and the wall in the use position. This arrangement may also have the advantage of reducing the overall weight of the apparatus since the struts 30 will be shorter and the brackets 32 will be located more towards the centre of the platform side edges, thereby allowing a less strong (less heavy) platform construction.

[0065] In addition, the safety railing 40 comprises a pair of upper side rails 46 which pivotally interconnect the two right posts 42, 44 and the two left posts 42, 44, respectively, at the upper ends of the posts. In the illustrated embodiment, an upper proximal rail 47, such as a tube or the like, interconnects the upper ends of the proximal posts 42.

[0066] According to the illustrated embodiment, each side rail 46 may extend distally beyond the distal posts 44 (FIGS. 2A, 2B and 3B) and may be provided with a revetment 46A at its proximal end facing the wall W. The purpose of the revetments 46A will become apparent from the following. The revetments 46A may optionally be designed as small wheels or rollers.

[0067] In the illustrated embodiment, the safety railing 40 further comprises, at an intermediary level between the upper ends of the posts 42, 44 and the platform 20, left and right intermediate rails 49A and an intermediate proximal rail 49B. In order to allow the user to access to the platform 20, the intermediate proximal rail 49B can be opened/removed, e.g. by a hook 49C or the like at one end of the rail 49B.

[0068] It will be appreciated that each one of the right-hand side and the left-hand side of the safety railing 40 is constructed as a foldable parallelogram, as best shown in the partly folded position of the railing 40 in FIG. 4A, in which the struts 30 are disconnected from the ladder 4 and the posts 42, 44 are pivoted about the pivot axis A1 and A2, respectively.

[0069] In order to secure the railing 40 in its use position and prevent such folding movement as shown in FIGS. 4A and 4B, the distal posts 44 may be releasably secured to the right and left sides, respectively, of the platform 20 by means of screws and threaded knobs 51 or by other means. In the illustrated embodiment, the screws and the knobs 51 engage the right and left platform borders 29. As an alternative, the screw-and-knob fixing may be arranged at the proximal posts 42 instead, or at both the distal and the proximal posts.

[0070] As mentioned above, the distance D between the proximal pivot axis A1 and the platform 20 has dual advantages: As described above, the first advantage of arranging the distance D is related to the advantage of the platform 20 being foldable over the lower ladder section 10 in the transport position of the apparatus 2 when the two ladder sections 10,12 overlap. The second advantage of arranging the distance D is related to the stability of the railing 40, especially the stability in the right-left direction, in the upright use position of the safety railing 40 as shown in FIG. 1.

[0071] If a user standing upon the platform 20 leans against for instance the right side of the safety railing 40, e.g. against the right-hand upper side rail 46, this will create a load or force on the right proximal post 42, as indicated by an arrow F1 as indicated in FIG. 2A. This force F1 will be transferred from the right proximal post 42 via the tube 47 and/or the member 49B to the left proximal post 42. Due to the manner in which the proximal posts 42 are mounted with its points of connection to the tube 13 located at a distance D below the platform 20, the left proximal post 42 will in this situation act as a lever and the platform 20 will act as the fulcrum (pivot point) for this lever. Accordingly, since the lower end of the lever (left post 42) is connected to the pivot tube 13 at the distance D from the fulcrum 20, the force F1 will effectively be counter-acted by a force F2 as indicated in FIG. 2A, resulting in a very stable safety railing construction. The similar effect applies obviously in the other direction if a load is applied on the left side of the railing 40. The effect is that the railing 40 is effectively stabilized compared to a design where the lower ends of the posts 42 would have been fixed only in level with the platform.

[0072] Forces acting on the distal posts 44 connected to the distal brackets 32 will in the same manner be counter-acted by the distal posts 44 acting as levers and forces from the pivot pins 34 acting on the lower ends of the distal posts 44.

[0073] In the illustrated embodiment, the tube 13 and the first pivot axis serves dual purposes. The tube 13 is used both for the pivotal connection of the platform 20 to the ladder and for connecting to the lower ends of the proximal posts 42 for obtaining the lever action. This provides a compact and cheap solution for obtaining both effects. In alternative embodiments, a separate axis may be provided for each one of the two functions.

[0074] It may also be noted that any user load acting on the upper proximal railing 47, as indicated by an arrow F3 in FIG. 2A, will be at least partly transferred to the ladder 4 via the struts 30.

[0075] To summarize, this design of the railing 40 and the lever function of the posts 42, 44 has the advantage that the railing structure is foldable as well as very stable in the use position, a combination which is generally difficult to obtain in foldable structures.

[0076] In order to enhance the stability of the apparatus 2 in its use position, the platform assembly 6 is further provided with a pair of stabilizing wall support arms or support members 80, including a right arm/member and a left arm/member. These elements will be referred to as arms in the following. Each arm 80 may be rotatably connected to the platform 20 at the distal platform side 24 for rotational movement in a plane parallel to the platform 20. The longer the arms, the better stability may be obtained as described above. Preferably, the outer end of each armor any member attached to the outer arm endwill have contact with the wall in the use position of the apparatus. In some embodiments, these two contact points will be the only wall contact points of the apparatus. In other embodiments, there may be one or more further points or areas of wall contact, such as at the platform 20. Such further contact points may be points of direct contact or points of indirect contact via wheels or rollers. As an example, the distance between the two distal wall contact points of the arms 80 may be about 1 500 mm for a platform width being about 680 mm, giving a ratio of about 2.2. According to one aspect, the distance between the distal points of contact should be at least twice the platform width. This ratio may be increased for increased stability and/or for making it easier to use the apparatus at wide windows.

[0077] Specifically, the wall support arms 80 may be movable, preferably manually by a user, between: [0078] a stowed arm position (see FIGS. 5A and 5B) in which the wall support arms 80 project out from the distal side 24 of the platform 20, typically at least partially or essentially completely along a proximal-distal direction perpendicular to the first pivot axis A1 thereby preventing use of the apparatus as a result of the arms 80 preventing the platform 20 from be positioned correctly in relation to the wall W, and [0079] a stabilizing arm position (see FIGS. 1 and 3A) in which the wall support arms 80 project sideways from the platform 20 in opposite right and left directions, respectively, for stabilizing the apparatus 2 in relation to the wall W.

[0080] In the illustrated embodiment, the wall support arms 80 are rotatably connected to the platform 20 at two rotational axes A3, extending at right angles to the platform 20 at the distal side 24 thereof and located at a distance from the right and left platform sides 26, 28. Each rotational axis A3 is located between an outer end and an inner end of the associated arm 80, thereby dividing each arm 80 into an outer arm portion and an inner arm portion. In the illustrated embodiment, each rotational axis A3 is implemented by a threaded pin, and for securing the arms 80 in their respective positions a handle or a knob 82 is threaded onto each pin in manner that the knob 82 may not be removed and lost, for instance by providing a deformation of the threading or by other means. Thus, the apparatus is preferably designed such that the wall supporting arms 80 cannot be detached and lost by the user.

[0081] In the preferred embodiment, the wall support arms 80 are located in level with the platform 20. More specifically, in the illustrated embodiment they are located on top of the platform 20, but it may also be possible to locate the arms 80 in the plane of the platform 20 or just below the platform.

[0082] According to the illustrated embodiment, the apparatus 2 may optionally further comprise arm engaging means 84, 86 which are structured and arranged to engage the wall support arms 80 in their stabilizing arm position to restrict any further movement of the arms 80 beyond the stabilizing arm position, when the arms 80 are being moved from their stowed arm position (FIG. 5B) in the transport position of the apparatus into their stabilizing arm position (FIG. 3A) in the use position of the apparatus. These arm engaging means 84, 86 comprise, in the illustrated embodiment, a central rotational stop member 84 which is arranged centrally on the platform 20 at the distal side 24 thereof and engages the inner arm portions, i.e. the ends of the inner arm portions, in the stabilizing arm position in FIG. 3A. This central rotational stop member 84 not only defines a rotational stop position for the arms 80, it also has an upper proximally extending extension 84A, which in the stabilizing arm position extends over each arm 80 as shown in FIG. 2A and 3A in order to prevent vertical movement of the arms 80 in relation to the platform 20 in the stabilizing arm position.

[0083] The arm engaging means 84, 86 further comprise a pair of right and left rotational stop recesses 86 formed in the distal ends of the right and left platform borders 29, as best illustrated in FIG. 2A. These stop recesses 86 not only define a rotational stop position for the arms 80. An upper extension 86A of each platform side border 29 extends over the recess 86 and over the associated arm 80 received in the recess 86 in order to prevent vertical movement of the arms 80 in the stabilizing position.

[0084] It will be appreciated that due to the design of the arm engaging means 84, 86 preventing vertical movement of the wall support arms 80 in relation to the platform 20 in the stabilizing arm position, no vertical forces have to be taken by the screws an and knobs 82 at the arm pivot axis A3.

[0085] The design, connection and movability of the stabilizing wall support arms 80 provide the apparatus 2 with a safety and stabilization feature which cannot be set aside by the user due to oversight or lost components. The arms 80 cannot be removed and lost, so the user does not have to locate and mount the arms when erecting the apparatus 2. More important, the design is such that the arms 80 effectively prevent any use of the apparatus unless they have been brought to their stabilizing arm position. In other words, the arms 80 have a dual function: they give stability in the use position of the apparatus 2 and they prevent use of the apparatus 2 if the stability function is not activated.

[0086] Also, the stabilizing arm position is maintained by gravity during use, which in combination with the arm engaging means 84, 86 effectively holds the arms 80 in correct aligned position when the user is standing upon the platform 20. The knobs 82 provide an additional security and will especially hold the arms 80 in position during the initial unfolding and erection of the apparatus 2.

[0087] In the illustrated embodiment, each arm 80 is provided with a wheel or roller 88 at an outer end of the arm 80 for engaging the wall W in the use position of the apparatus. In a preferred embodiment, the wheels 88 may be rotatable in one direction only, such that the wheels 88 may rotate in a first direction against the wall when the apparatus is raised into its use position against the wall W but prevented (or at least braked) from rotating in an opposite second direction in order to prevent unintentional lowering of the platform 20. This one-way function may be a complete rotational blocking function or just a brake function. Reference numeral 89 indicate means for accomplishing this one-way function of the wheels 88.

[0088] In other embodiments of the apparatus, the arms 80 may be provided with other contact means instead of wheels 88 or in addition to the wheels 88.

[0089] In some embodiments, each arm 80 may have an individually adjustable length, for instance by using telescopic arms, in order to suitably adjust the point of contacts of the wheels 88 against the wall W.

[0090] As mentioned above, the illustrated embodiment of the apparatus also comprises a ground support assembly 70. In a simpler design of the apparatus, the ground support assembly 70 may not be necessary.

[0091] In the embodiment illustrated in FIG. 1, the ground support assembly 70 comprises (see FIG. 3A) a horizontal central beam 72 fixedly connected to the rear side of a lower part of the lower ladder section 10. The ends 73 of the central beam 72 extend beyond the rails of the lower ladder section 10 and are angled in a plane perpendicular to the ladder 4 towards the wall W. A pair of pivotal ground support legs 74 are pivotally connected to the angled ends of the central beam 72 by means of screws and threaded knobs 76. Optionally, embossed washers may be used for this connection whereby the arms 74 are effectively looked in position already for a relatively low torque applied by the knobs 76. As with the connection of the stabilizing arms 80, the threads of the screw engaging the knobs 76 may be deformed in order to prevent removal the ground support legs 74.

[0092] With reference to FIGS. 5A and 5B, similar to the fail-safe design of the wall support arms 80, which are designed such that they prevent correct positioning of the apparatus 2 unless they are brought into their stabilizing arm position, the ground support assembly 70 is also designed such that it prevents a correct positioning of the apparatus 2 unless the stabilizing function of the ground support assembly 70 is activated by pivoting the ground support legs 74 from their transport position (FIGS. 5A and 5B) to their stabilizing position (FIGS. 1 and 3A). As will be seen in FIG. 5A, showing the ground support legs 74 in their transport position extending in the direction of the ladder 4, the ground support legs 74 extend beyond the lower rail ends of the ladder 4 with a distance e, thereby preventing the ladder 4 from being placed on the ground G unless the user rotates the support legs 76 to their ground stabilizing position as shown in FIG. 1.

[0093] It may be preferred that the ground support legs 74 are mounted such that they cannot be rotated upwardly from their stabilizing position in FIGS. 1 and 3A, in order to ensure that the legs protrude beyond the ladder in the transport position.

[0094] The apparatus 2 as described above is used in the following manner: The apparatus 2 is initially transported in its folded transport position (FIG. 6) to the site where it is to be used. Optionally, the apparatus 2 may be rolled on the transport wheels 50 and placed on the ground as shown in FIG. 6C to E. Next, the ladder 4 is pivoted or folded out from the platform 20 and secured by the struts 30 and pins 38. Thereafter, the ladder 4 is laid down on the ground. The safety railing 40 is fixed in position in relation to the platform 20 by the knobs 51. The configuration of the apparatus 2 is now as illustrated in FIG. 5A and 5B. In this configuration, the wall support arms 80 are still extending out from the platform 20 in the proximal-distal direction and the ground support legs 74 are still extending beyond (distance e) the lower end of the ladder 4. Thereby, the user cannot place the apparatus 2 against the ground G and the wall W without first moving the arms 80 and the legs 74 to their stabilizing use positions as shown in FIG. 1.

[0095] Thus, the wall support arms 80 will next be rotated to their stabilizing arm position and fixed by the knobs 82, and the ground support legs 74 will be rotated away from their stowed leg position (such that the lower end of the ladder may be put on the ground G).

[0096] Next, the apparatus 2 is raised and the wheels 88 of the wall support arms 80 are placed against the wall W for stabilizing the apparatus 2. Thereafter, the position of the platform 20 is adjusted to a suitable work level by extending the upper ladder section 12, while the wheels 88 will be rolling against the wall W. Next, the ladder sections 10, 12 are locked in relation to each other by the hooks 18.

[0097] The lower part of the ladder 4 is then adjusted on the ground G such that the platform 20 becomes horizontally. The revetments 46A of the upper side rails 46 will then be at a distance a from the wall W as shown in FIG. 3B. The ground support legs 74 are now also adjusted in relation to the ground G and fixed by the knobs 76.

[0098] With respect to the vertical stability of the apparatus 2, the positions of the points of contacts and the frictional forces at the points of contacts are essential. If the horizontal distance d (see FIG. 3B) between the wall W and the ground support legs 74 is increased, then the frictional forces at the points of contacts must also increase in order to maintain vertical stability. The means 89 for one-way rotation restricts or brakes the wheels 88 from rolling downwards against the wall W, resulting in frictional forces between the wheels 88 and the wall W.

[0099] Initially, the downwardly directed force from the platform ladder apparatus 2 is primarily taken by the ladder's 4 point of contact against the ground G, and to a less degree by the points of ground contact of the ground support legs 74. The reason therefore is that the final adjustment of the ground support legs 74 took place while the apparatus 2 was already standing on the ground G and leaning against the wall W.

[0100] If for some reason the frictional forces against the wall W and/or the ground G should be insufficient, and a sliding movement should occur at the points of contact, for instance due to dynamic forces acting on the apparatus 2, then the ground support legs 74 will be pressed harder against the ground G with a resulting increase of frictional forces in relation to the ground G, which will counteract the sliding movement of the apparatus 2. If the apparatus 2 nevertheless should continue its sliding movement, then the distance a (see FIG. 3B) will be gradually reduced and the revetments 46A will eventually be brought into contact with the wall W, resulting in additional frictional forces counteracting the sliding movement. If the revetments 46A should be brought into contact with and press against the wall W, a new geometric structure is obtained in which the apparatus is supported against the wall at a higher level. This, in its turn, results in a reduction of the forces which tend to make the apparatus slide.

[0101] FIG. 7 illustrates the apparatus in FIGS. 1 to 6, but with a second embodiment of a ground support assembly 90. In this embodiment, the ground support assembly 90 comprises two relatively longer ground support legs 92 which are pivotally connected to the lower ladder section 10 via brackets 94. The position of the brackets 94 may be adjusted along the ladder section 10 and be fixed by screw means (not shown) in the desired position. The brackets 94 cannot be adjusted beyond stop means 96 in order to prevent the user from setting aside the fail-safe function of the ground support assembly 90. The pivotal movement of the ground support legs 92 is restricted by straps 98 having an adjustable length. As with the assembly 70, the ground support legs 92 extend beyond the lower end of the ladder 4 in their stowed leg position, preventing the user from placing the ladder 4 against the ground G unless the ground support legs 92 have been brought into their stabilizing leg position.

[0102] FIG. 8 illustrates the apparatus in FIGS. 1 to 6 but with a third embodiment of a ground support assembly 100. In this embodiment, the ground support assembly 100 comprises a horizontal beam 102 fixed to the lower ladder section 10 and a rotatably mounted ground support 104 having a central portion and right and left angled side portions extending to the right and the left beyond the ladder in the stabilizing position. The ground support 104 is pivotally connected to the central beam 102 by means of a screw 106 and a nut provided with a lever 108. The position of the horizontal beam 102 along the ladder may optionally be slightly adjustable in order to allow a fine-tuning of the ground contact points of the ground support 104.

[0103] In all embodiments of the ground support assembly, the design is preferably such that it is not possible to remove the ground support assembly from the apparatus.

[0104] FIG. 9 illustrates a second embodiment of a platform ladder apparatus in its position of use. The second embodiment is in many aspect similar to the first embodiment described above. However, the second embodiment further comprises a pivotable hatch arranged on the proximal side of the platform. FIG. 9 shows the hatch in its raised open position allowing the user to access the platform. In its horizontal closed position (not shown), the hatch and the platform will together form an extended platform. Further, the safety railing is modified in the second embodiment in that the distal posts 44 in the first embodiment are not present and instead a pair of additional vertical posts are arranged on the proximal side of the hatch, said additional vertical posts being connected to horizontal beams extending proximally from the platform sides. Finally, the struts 30 in the first embodiment fixing the platform in relation to the ladder are replaced in the second embodiment with a pair of shorter struts arranged on the front side of the ladder and connected to the lower ends of said additional vertical posts. The struts in the second embodiment will take both compression forces and traction forces depending on the position of the user, whereas the struts 30 in the first embodiment will mainly take compression forces.