RELATED APPLICATIONS

The present application claims priority from earlier filed Australian provisional patent application numbers, 2015903421 filed on 24 August 2015 and 2016902513 filed on 27 June 2016, the entire contents of which are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates generally to ladders and in particular, to an extension member for attachment to a conventional ladder that provides walk- through access to a user from the ladder onto an elevated surface or platform.

BACKGROUND OF THE INVENTION

Ladders, of various forms and configurations, have been used for many years to provide an individual with the ability to access an elevated area. Step ladders, which generally comprise two pairs of legs hinged together at a central region, provide a means for an individual to access an elevated area to perform a task at such an elevated height in a substantially stable manner, depending upon how level the surface which supports the pairs of legs is.

Extension ladders generally comprise at least two ladders mounted together, with master ladder defining the general structure of the arrangement and a slave ladder mounted within the master ladder in a manner that is able to extend and retract from the master ladder as desired. Each of the master and slave ladders comprises a pair of posts that extend substantially parallel to each other with a plurality of rungs extending between the posts in a substantially orthogonal manner. Extension ladders are configured to rest against a structure and are generally not self-supporting, in the manner that step ladders are configured.

In use, extension ladders are often used to provide a user with the ability to access a higher level of a pre-existing structure, such as a roof of a building or the like. The extension ladder is typically arranged to rest against a structure such that the lower end of the posts of the master ladder are supported on a ground surface and the slave ladder is extended as appropriate such that the upper region of the extension ladder rests against the edge of the upper level to be accessed, such as a roof. In this regard, in order for a user to gain access to the roof of the building structure, the user scales the ladder and steps around the upper end of the ladder to transfer from the ladder to the upper level. The stability of the extension ladder generally resides in the slope of the ladder and the amount of friction that exists between the lower end of the posts of the master ladder and the ground surface.

It will be appreciated that due to the above described means for supporting the ladder against a building stmcture or the like, the ladder retains a degree of stability provided that, in use, the user remains between the posts of the master ladder. This ensures that the weight of the user is maintained in a substantially balanced manner between the lower ends of the posts. Then, should the user seek to transfer from the ladder to the upper level, they must step around the upper end of the ladder to access the roof or upper level of the building. Such an action results in their weight becoming distributed outside of this region and outside of the posts of the master ladder. This will result in the weight distribution of the user having a moment force associated therewith which can destabilise the master ladder and cause the master ladder to lose stability. It will be appreciated that any loss of stability of the master ladder will cause the ladder, and in most circumstances, the user, to topple over, which can cause significant injury to the user, as well as damage the structure and also injuiy to others in the vicinity of the ladder.

For this reason a variety of stabilising means have been proposed for use with both step and extension ladders. Many such stabilising means have been directed towards providing additional grip to the base of the posts in contact with the ground surface or by various means for fixing the upper region of the ladder in position against the building structure and the like. Whilst such proposals have proven successful in improving the safety of many existing ladders when correctly installed, due to the often complicated nature of such devices and the manner in which they are to be installed, it is common for the devices to be incorrectly installed or disregarded altogether, further compromising the stability of the ladder and having no effect on improving the safety of the ladder. Such devices also do not typically address the problem, as the user must still step around the ladder to access the higher level and bring their weight distribution outside of the posts of the master ladder as they are more concerned with tethering the ladder in order to deal with such issues rather than avoid the issue in the first instance.

One such device that is directed towards addressing the need for a user to step around the upper end of the ladder in order to transfer to the upper surface of the structure is disclosed in United States Patent No. 7,322,442 filed in the name of Bruce D. Clark et al. This device generally comprises a pair of extension members attached to both upper ends of the posts of a ladder so as to extend the posts to provide a pair of extending hand rails for the user to pass between when transferring from the ladder to the upper surface. Whilst such an arrangement overcomes the need for the user to step outside of the posts of the ladder, such an arrangement is not suitable for use with an extension ladder as it requires attachment to the upper ends of the posts and reduces the posts ability to travel within a master ladder. Further, such a system as disclosed in this patent is cumbersome to attach to an existing ladder and introduces the risk that it will not be employed correctly in many instances due to such a complicated and difficult means of attachment.

Thus, there is a need to provide an attachment device for a ladder that is able to be used with an extension ladder and which is able to be simply fitted over the existing ladder without the need for significant structural modifications to the existing ladder or multiple assembly parts.

The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the above prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.

STATEMENT OF INVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the invention there is provided an attachment member for providing walkthrough access to an elevated surface from a ladder comprising:

a pair of rail members attachable to an upper end of the ladder, the rail members being configured to have a lower region, wherein the pair of rail members are at least partially received within the upper end of the ladder, and an upper regio wherein the pair of rail members at least partially extend from the upper end of the ladder and at least partially diverge to define an opening that is wider than the upper end of the ladder to enable a user to pass therebetween to access the elevated surface.

In one embodiment, the lower region of the rail members comprises a plurality of slots formed therein to engage with rungs of the ladder. The plurality of rung members may extend between the pair of rail members in the lower region thereof. Each of the rung members may be configured to extend over a corresponding rung of the ladder so as to support the user when using the extension member. The rung members may have a curved surface that substantially covers the corresponding rung of the ladder.

Each rail member may comprise an L-shaped channel that is configured to fit over a front and inner surface of the ladder. Each rail members may comprise at least three slots configured to engage with the three uppermost rungs of ladder. The at least three slots may comprise an opening to receive the corresponding rung of the ladder and a closed end portion in communication with the opening to capture and engage the corresponding rung under the weight of the extension member acting against the ladder.

At least one of the at least three slots may have a locking member associated therewith that functions to substantially enclose the corresponding rung when the corresponding rung of the ladder is fully received within the at least one of the slots.

The upper regions of each of the rail members may have a stabilising member mounted thereto to engage with a structure associated with the elevated surface to provide stability to the extension member during use. The stabilising member may project from the rail members to engage with the structure and may be configured s as to be adjustable in projecting length.

The upper region of the rail members may be configured to comprise a diverging portion that widens an opening between the rail members and a parallel portion that extends the widened opening between the rail members.

A hand rail may extend between the upper region and the lower region of the rail members for gripping by a user as they pass through the extension member.

Accordingly, in another aspect of the invention there is provided an extension ladder for providing walkthrough access to an elevated surface from a ladder comprising: a master ladder configured to be supported on a ground surface and comprising a pair of master posts extending in a parallel manner and a plurality of master rungs extending therebetween at regular intervals,

a slave ladder having a pair of slave posts extending in a parallel manner and a plurality of slave rungs extending therebetween at regular intervals, the slave ladder being configured to be received within the master ladder so as to be slidably movable to extend from an upper end of the master ladder;

wherein the slave ladder has an upper end where the slave posts at least partially diverge to define an opening that is wider than a remainder of the slave ladder to enable a user of the extension ladder to pass therebetween to access the elevated surface from the extension ladder.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which :

Fig. 1 is a perspective view of an extension ladder in accordance with the prior art;

Fig. 2 is a perspective view of an extension member for a ladder in accordance with an embodiment of the present invention;

Fig. 3 is a front view showing the extension member of Fig. 2 attached to an upper end of an extension ladder of Fig. 1, in accordance with an embodiment of the present invention;

Fig. 4 is a side view of the arrangement of Fig. 3;

Fig. 5 is a depiction of the arrangement of the present invention depicted in Fig. 3 in use;

Fig. 6 is a depiction of an alternative embodiment of the present invention;

Fig. 7 is a perspective view of an extension ladder incorporating the alternative embodiment of the invention as depicted in Fig. 6;

Fig. 8 is a side view of an embodiment of a locking device in accordance with the present invention in a pre-engaged state; Fig. 9 is a side view of the embodiment of the locking device of Fig. 8 in an engaging state;

Fig. 10 is a side view of the embodiment of the locking device of Fig. 8 in an engaged state;

Fig. 1 1 is a cross sectional side view of a ladder in accordance with another embodiment of the present invention incorporating a stabilising arm shown attached to one of the rail members of the attachment; and

Fig. 12 is a side view showing a ladder incorporating the attachment of the present invention with the stabilising system of Fig. 1 1 functioning to stabilise the ladder for use.

DETAILED DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

The extension member of the present invention will be described below in relation to its application for use with a pre-existing extension ladder 10 of the type as depicted in Fig. 1. However, it will be appreciated that the extension member of the present invention may be used with any variety of pre-existing and new ladders whilst staying within the spirit of the present invention.

Referring to Figure 1 , an extension ladder 10 in accordance with the prior art is depicted. The extension ladder 10 comprises a master ladder 12 having a pair of parallel extending posts 13 connected therebetween by a plurality of rungs 14 equi-spaced along the length of the posts 13. The base of the posts 13 comprise foot members 15 that are configured to support the master ladder on a ground surface. In one embodiment, the foot members 15 may be pivotally mounted to the base of the posts 13 and may have friction inducing material, such as rubber or the like, mounted to an undersurface thereof. In other embodiments, the foot members 15 may be merely the ends of the posts in contact with the ground surface.

A slave ladder 16 is mounted to the master ladder 12 so as to fit therein. The slave ladder also comprises a pair of parallel extending posts 17 connected therebetween by a plurality of rungs 18 equi-spaced along the length of the posts 17. As the slave ladder 16 is configured to be mounted within the master ladder 12, the distance of separation between the posts 17 is less than the distance of separation between the posts 13 of the master ladder 12.

In the embodiment as depicted in Fig. 1 , a pulley 11 is mounted in the middle of one of the upper rungs 14 of the master ladder 12 and a rope 5 rides over the pulley 1 1 and is attached at one end to the middle of the lower rung 18 of the slave ladder 16 as shown, and the other end to a locking mechanism 8 for locking the rungs of the slave ladder 16 and the master ladder 12 together. The slave ladder 12 is able to freely slide within the master ladder 12 and one or more runners (not shown) may be provided to facilitate this sliding movement. As will be appreciated, by pulling on the rope 5, the slave ladder 16 slidingly extends beyond the end of the master ladder 12 to a desired length as required to achieve a desired height. It will be appreciated that a user of the extension ladder 10 of Fig. 1 typically locates the ladder 10 against the structure such that the foot members 15 of the master ladder 12 are supported on a ground surface and raises/lowers the slave ladder 16 such that it is supported on the edge of the level being accessed.

Referring to Fig. 2 an embodiment of the extension member 20 in accordance with the present invention is shown. The extension member 20 generally comprises a body that resembles a smaller ladder that is fitted over the upper end of the slave ladder 16 of the extension ladder 10. In this regard, the body comprises a pair of rail members 21 in the form of L-shaped channels of metal, such as steel, aluminium, or other material. The rail members 21 each have an upper or front surface 22 that is configured to extend over the upper or front surface of the posts 17 of the slave ladder 16, and a wall 23 that extends perpendicular to the front surface 22 and which is configured to be received over the inner surface of the posts 17 of the slave ladder 16, when the extension member is fitted to the ladder 10 for use. The walls 23 extend parallel to each other and are separated a sufficient distance so as to fit between the posts 17 of the slave ladder 16.

A plurality of rung members 24 extend between the walls 23 at predetermined distances along the length thereof. The rung members 24 are configured to fit over the rungs 18 of the slave ladder 16 when the extension member 20 is fitted thereto. In this regard, the rung members 24 may have a curved or flat configuration to fit over the rungs 18 of the slave ladder 16 such that when used, the rung members 24 receive and support the weight of the user as they use the ladder 10 to access an elevated area.

A plurality of notches 25 are formed in the walls 23 of the rail members 21 to facilitate attachment of the extension member to the slave ladder 16, as is depicted in Fig. 2. Each of the notches 25 comprise an open portion 26 that extends from the rear edge of the walls 23 into a closed portion 27. The open portion 26 is shaped to receive the rungs 18 of the slave ladder 16 which are then captured by the closed portion 27 to securely locate the extension member 20 on the slave ladder 16 under the force of gravity. As the closed portion 27 of the notches 25 is located above the open portion 26, upon entry of the rungs 18 into the open portion, the weight of the extension member causes the rungs to be captured into the closed portions 27 of the notches 25. As the spacing between rungs is consistent for most ladders, the notches 25 to be spaced a predetermined distance apart along the length of the rail members 21 to accommodate use with a variety of different ladders 10. It will be appreciated that, when the extension member 20 is located on the rungs 18 of the slave ladder 16 in this manner, the rung members 24 extend over and cover the rungs 18 of the slave ladder 16.

In the embodiment as depicted in Figs. 2 - 5, the extension member 20 comprises three rung members 24 and is configured to fit over the top three rungs 18 of the slave ladder 16. It will be appreciated that other lengths and arrangements of the extension member 20 are also envisaged.

Referring to Figs 8 - 10, an embodiment of the present invention incorporating a locking system is depicted. In this embodiment, a locking member 100 is mounted to the inner wall 23 of the rail member 21 of the extension member 20 by way of a pivot point 105, such as a rivet or the like. The locking member 100 will preferably be mounted to both inner walls 23 of rail members 21 of the extension member 20, and has an elongate body with a hooked head portion 1 10 located at its distal end. The head portion 1 10 has an angled bottom face 1 12 that terminates at a point 1 15. A substantially perpendicular surface 113 extends from the point 1 15 back to the head portion 1 10.

In use, the extension member 20 is positioned over the slave ladder and is lowered into position in the direction of arrow A, until the rung members 24 are received over the rungs 18 of the slave ladder 16. As the extension member 20 is lowered, in the position of Fig. 8, the angled surface 112 of the locking member 100 comes into contact with the rung 18 of the slave ladder 16. The angle of the angled surface 112 causes the locking member 100 to move away from the rung 18 in the manner as shown in Fig. 9. Continual movement of the extension member in the direction of arrow A will cause the point 1 15 of the locking member 100 to move over the rung 18 after which it will return to position, under gravity, below the rung 18 such that the hooked head portion 1 10 captures the rung 19 between the head portion 1 10 and the rung member 24 (Fig. 10). This then locks the extension member 20 in position and prevents any inadvertent removal.

As is more clearly shown in Fig. 3, the rail members 21 extend substantially parallel and define an opening or width 'Y' which is substantially the same width as the slave ladder 16. Once the rail members 21 pass beyond the ends of the posts 17 of the slave ladder 16, the rail members 21 diverge at a common angle along divergent portions 28. After diverging for a distance, the rail members 21 return to travel in a parallel relationship with a wider opening width 'X'. This wider opening 'X' is sufficient to allow a user to walk through the opening to access the elevated surface, without having to step around the posts 17 of the slave ladder 16. This is shown in Fig. 5.

To facilitate ease of movement of the user as they walkthrough the extension member 20, a handrail 30 is provided on either sides of the extension member 20. The handrail 30 is in the form of a metal rail or tube that is welded or otherwise affixed to the upper surface 22 of the rail members 21 adjacent the uppermost or widest portion. The handrail 30 then extends directly down and retains the wide spacing 'X' to be attached to the rail member 21 at a lower region thereof, where the rail members 21 are at their narrowest spacing Ύ'. Such an arrangement of the handrail 30 ensures that the hand rail 30 does not impede movement of the user as they access the elevated surface.

It will be appreciated that the embodiment of the extension member 20 of the present invention as depicted in Figs. 2 - 5 enables the extension member to be simply fitted over an existing slave ladder of an extension ladder without affecting the ability of the slave ladder to slide within the master ladder. This is achieved by the rails fitting over only the upper and inner surfaces of the slave ladder and thereby not impeding sliding movement of the slave ladder. Due to the provision of the rung members as a structural part of the extension member 20, the extension member 20 becomes part of the slave ladder and extends the slave ladder to support the user as the user climbs the ladder and walks through the wider opening of the extension member 20 and onto the elevated surface. It will be appreciated that the extension member 20 of the present invention does not require any modification of the existing ladder 10 and does not require attachment of any external parts, as is the case with many of the prior art proposals for stabilising a ladder in use.

Referring to Fig. 6, an alternative embodiment of the present invention is depicted. This embodiment is in the form of a stand-alone slave ladder 40 having a pair of posts 42 and rungs 44 extending therebetween at regular intervals along the length of the posts 42. The upper end of the posts 42 are configured so as to diverge to a wider opening with the absence of rungs 42 therebetween, in the manner as discussed above.

As is depicted in Fig. 7, the slave ladder 40 is configured to be mounted to a master ladder 12 to form an extension ladder 50 whereby the slave ladder 40 is slidable with respect to the master ladder 12 in the manner as discussed previously in relation to Fig. 1. It will be appreciated that such an arrangement provides the ability for a user to use the extension ladder 50 as a stand-alone product that does not require an attachment to be fitted to the slave ladder for the extension ladder 50 to provide the walkthrough effect. The upper end of the slave ladder 40 is already configured to access an elevated platform or the like. A handrail 45 is mounted at either sides of the wider opening to provide support for the user as they access the upper platform from the ladder 40. It will be appreciated that the ladder 50 created from this embodiment of the invention may have a variety of lengths to access a variety of height requirements.

In yet another embodiment of the present invention depicted in Fig. 1 1, to improve stability of use of the present invention, the extension member 20 may be fitted with a pair of stabiliser arms 200 to opposing sides of the rail members 21. The stabiliser arms 200 comprise a pair of L-shaped members having a straight portion 201 that extends substantially perpendicular from the rail member 21 and an angled end portion 202 that extends downwardly therefrom. Each of the stabiliser arms 200 are mounted to the rail members 21 by way of a pin 210 that passes through a sleeve formed in the rail member to be received in a hole 205 formed in the straight portion 201 of the member 200. A plurality of holes 205 are provided to enable the length of extension of the stabiliser member 200 to be varied as required.

It will be appreciated that in use, the stabiliser arms 200 extend from the upper region of the ladder in the manner as shown in Fig. 12. This causes the upper region of the ladder to grip the roof structure, such as a guttering as shown, thus providing added stability to the ladder in use. It will be appreciated that other arrangements of the stabiliser arms 200 are also envisaged. It will be appreciated that the device of the present invention provides for a simple and effective means for safely accessing an elevated surface or platform using a conventional ladder. The device can be simply applied to a conventional ladder to convert the ladder to a walk-through ladder without having to assemble various parts and apply screws and bolts. Similarly, after use the device can be simply removed from the ladder and stored for ongoing use by the user, as required.

Throughout the specification and claims the word "comprise" and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word "comprise" and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the invention.