WO2004109051A1

WO2004109051A1 - Ladder

Info

Publication number: WO2004109051A1
Application number: PCT/AU2004/000754
Authority: WO
Inventors: James Leslie Mann
Original assignee: Prairie Enterprises Pty Ltd
Priority date: 2003-06-04
Filing date: 2004-06-04
Publication date: 2004-12-16
Also published as: NZ544143A; AU2003902799A0

Abstract

A ladder (11) comprising a plurality of primary support members, in the form of rungs (15), releasably supported in spaced apart relation by at least one elongate element (13). The at least one elongate element (13) comprising a plurality of secondary support members (17) adapted to slidingly engage each other in an end to end relationship to form the at least one elongate element (13).

Description

"Ladder"

Field of the Invention

The present invention generally relates to ladders. In particular the invention is a ladder provided in a disassembled condition which may be assembled on site to the required length.

Background Art

Most available ladders are supplied in predetermined lengths. As such, the purchase of a ladder is typically governed by the particular application to which the ladder will be used. There are however, applications where a specific ladder length is necessary, requiring the ladder to be made to a predetermined length.

One such application where the ladder is required to be tailored to the required length is in sewer systems where a ladder allows personnel to access the sewer through a manhole. In the designing and planning of the sewer systems, ladders of different sizes are required to accommodate the constraints dictated by the position of the manhole relative to the ground. These constraints additional to the constraints imposed by the various regulations and standards relating to ladders.

A particular problem with ladders for sewer systems is that by the time the civil works are completed, the length of the ladder ordered, whilst meeting the specification as designed, may no longer meet the dimensions of the sewer after construction. This may be due to various factors arising during civil construction which change the sewer structure as originally designed.

A typical method of fixing ladders relative to a manhole is to insert a ferrule into the manhole wall so that a step may be secured thereto. With the settling and movement of the earth surrounding the manhole, it is quite common for water and other contaminants to pass through the hole and into the sewer. This leakage is undesirable and generally may only be rectified by digging an access hole adjacent the manhole to allow a repairer to attend to the problem from outside the manhole.

The preceding discussion to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or an admission that any of the material referred to was or is part of the common general knowledge in Australia as at the priority date of the application.

It is an object of this invention to provide a ladder system which addresses the same specification of conventional ladders but is able to be assembled quickly and easily to the desired length.

Disclosure of the Invention

The present invention provides a ladder comprising a plurality of primary support members releasably supported in spaced apart relation by at least one elongate element, the at least one elongate element comprising a plurality of secondary support members adapted to slidingly engage each other in an end to end relationship to form the at least one elongate element.

Preferably each, secondary support member is adapted to receive at least one of the plurality of primary support members.

In contrast to the prior art once the environment within which the ladder will be fitted has been completed, the relevant section may be measured and the ladder may be assembled to the required length. Furthermore, means to secure the ladder in place may be cast in the particular civil construction and the ladder can be assembled and secured thereto, obviating the need to drill holes through the civil works for the placement of securing bolts. Preferably there are two elongate elements. Preferably each elongate element defines a side of the ladder and supports the plurality of primary support members therebetween.

Preferably each primary support element defines a rung to support a person using the ladder.

Preferably each secondary support member supports one end of one rung such that the length of each secondary support member determines the distance between adjacent rungs.

Each secondary support member may provide an inner face and an outer face.

Each secondary support member may comprise an elongate intermediate portion, a first end portion located at one end of the intermediate portion and a second end portion located at the other end.

The first end portion may comprise a neck portion extending from the intermediate portion, and a head portion extending from the neck portion and having a recessed portion therein adapted to releasably receive the end of the rung.

The neck portion may extend substantially parallel to the longitudinal axis of the secondary support member. The head portion may then extend from the neck portion, sloping away from the longitudinal axis and towards the intermediate portion. The head portion may then extend away from the intermediate portion and taper towards the longitudinal axis of the secondary support member before terminating at a first edge substantially perpendicular to the longitudinal axis.

Preferably the recessed portion extends inwardly from the inner face and terminates a predetermined distance from the outer face, such that it does not go beyond the outer face. The recessed portion may be open along the first edge of the first end portion such that an end of a rung is slidingly receivable in the recessed portion in a direction parallel with the longitudinal axis of the secondary support member.

Preferably the second end portion comprises a cut out section. The cut out section may be contoured to slidingly receive the first end portion of an adjacent secondary support member in a direction transverse to the longitudinal axis, and providing a snug fit between adjacent secondary support members.

Preferably the second end portion also comprises a projection extending into the cut out section. The projection may extend a predetermined distance along the longitudinal axis of the secondary support member.

Preferably the projection extends in the transverse direction from the inner surface of the secondary support member and terminates a predetermined distance from the outer face. Preferable this predetermined distance is substantially the same as the depth of the recessed portion located in the first end portion. Hence when two secondary support members are coupled together, the projection is received within the recessed portion of the other secondary support member.

Preferable each end of each rung may have a slot in an upper surface. The slot may extend inwardly a predetermined distance from the end of the rung substantially parallel to the longitudinal axis of the rung. The slot may be adapted to receive the projection of the second end portion of the secondary support member.

Preferably the ladder also comprises a plurality of locking means which, when assembled, prevents adjacent secondary support members unintentionally disengaging from each other and releasing the primary support member.

Each locking means may be received in each end of each rung to prevent adjacent secondary support member disengaging. Preferably each end of each rung also comprises an aperture in communication with the slot. Preferably the aperture extends from the slot through to the underside of the rung.

Each locking means may be adapted to be releasably retained in the aperture.

The locking means may comprise a tab section which is received in the slot and abuts the projection of the second end portion in the secondary support member, preventing it from disengaging the first end portion of the adjacent secondary support member when in an assembled condition.

The locking means may comprise at least one latch extending laterally from the tab section. Preferably the at least one latch is resiliently flexible in a transverse direction.

When assembled, the at least one latch may engage an edge of the aperture to releasably retain the locking means thereto.

Preferably the locking means comprises two latches.

Brief Description of the Drawings

The invention will be better understood by reference to the following description of a specific embodiment thereof as shown in the accompanying drawings in which:

Figure 1 is a cross sectional view of a section of an assembled ladder;

Figure 2 is a side view of a secondary support member from the inner face;

Figure 3 is a cross-sectional side view down a longitudinal axis of the secondary support member;

Figure 4 is a view similar to Figure 2 but from the outer face; Figure 5 is an end view of a first end portion of the secondary support member;

Figure 6 is an end view of a second end portion of the secondary support member;

Figure 7 is a plan view of an end section of a rung;

Figure 8 is a cross-sectional side view of the end section of the rung;

Figure 9 is a front view of a locking means;

Figure 10 shows two secondary support members in sliding engagement, minus a rung;

Figure 11 is a perspective view of the end of a rung received in the first end portion of the secondary support member;

Figure 12 is a perspective view of an adjacent secondary support member slidingly engaging the partly assembled section shown in figure 11 ;

Figure 13 is a perspective view of the section shown in figure 12 assembled;

Figure 14 is a view similar to figure 13 with a locking means being inserted in the rung;

Figure 15 is a perspective view of a completely assembled section of the ladder;

Figure 16 is a perspective view from underneath a section of the assembled ladder. Best Mode(s) for Carrying Out the Invention

Referring to Figures 1 and 10, the invention according to an embodiment is in the form of a ladder 11 comprising two elongate elements 13 which support a plurality of primary support members in the form of rungs 15 therebetween.

Each elongate element 13 comprises a plurality of secondary support members 17 which slidingly engage each other in an end to end relationship to provide an elongate element 13, the length of which is governed by the number of secondary support members 17 used.

Referring to figures 2 to 6, each secondary support member 17 comprises an inner surface 19, an outer surface 21 , a first end portion 23, a second end portion 25 and an intermediate portion 27.

The first end portion 23 comprises a neck portion 29 which extends from the intermediate portion 27 along a longitudinal axis 31 of the secondary support member 17. The first end portion 23 also comprises a head portion 33 extending from the neck portion 29. The head portion 23 initially extends outwardly from the neck portion 29 in a direction towards the intermediate portion 27 to provide angled shoulders 35 before extending away from the intermediate portion 27 and tapering towards the longitudinal axis 31 to terminate at a first edge 37.

The head portion 33 also comprises a recessed portion 39 having an opening 41 along the first edge 37 and extending transversely from the inner surface 19 and ending a predetermined distance from the outer surface 21.

The second end portion 25 comprises a cut-out section 43 which mirrors the profile of the first end section 23 such that the first end portion 23 may be slidingly received over the second end portion 25 of an adjacent secondary support member 17 such that there is a snug fit between adjacent secondary support members 17 when coupled together, as can be seen in figure 10. The second end portion 25 also comprises a projection 45 extending into the cutout section 43 along the longitudinal axis 31. The projection 45 extends from the inner surface 19 and terminates substantially the same distance from the outer surface 21 as the recessed portion 39 of the first end section 23, for reasons which will be detailed below.

Referring to figures 7 and 8, each end 47 of each rung 15 is adapted to be slidingly received in the recessed portion 39 of the first end portion 23.

Each end 47 of each rung 15 comprises a slot 49 extending from the end 47 and terminating a predetermined distance therefrom. Each end 47 also comprises an aperture 51 in communication with the slot 49 and a bottom edge 53 of each rung 15.

Referring to figure 9, the ladder 11 also comprises locking means 55. The locking means 55 comprises a tab 57 and two latches 59 resiliently displaceable.

The assembly of the ladder 11 from the component parts is depicted in figures 11 to 16. As shown in figure 11 , the first step in assembling the ladder 11 is to place each end 47 of the rung 15 in the recessed portion 39 of the first end portion 23 of a secondary support member 17b, such that it is slidingly received in a direction parallel to the longitudinal axis 31.

When the rung 15 is in position, the second end portion 25 of a further secondary support member 17a is caused to slidingly engage the first end portion 23 of the secondary support member 17b, as best shown in figure 12. This engagement is in a direction transverse to the longitudinal axis 31 and is such that the second end portion moves in a direction from the inner surface 19 of the secondary support member 17b towards the outer surface 21. During this engagement the projection 45 is aligned and received in the slot 49 of the rung 15.

When adjacent secondary support members 17 are in engagement the locking means 55 is inserted into the slot 49 such that the latches 59 are received in the aperture 51 , as best shown in figures 14, 15 and 16. As the locking means 55 is inserted into the aperture 51 the latches 59 are caused to move inwardly until they reach the end of the aperture 51 and engage the sides of the countersunk section, to be releasably retained therein.

When the secondary support member 17a is fitted to an adjacent secondary support member 17b, the opening 41 of the recessed portion 39 is blocked, preventing the release of the rung 15 therefrom.

When the locking means 55 is in place the tab 57 abuts against the projection 45 of the second end portion 25 to ensure the secondary support member 17a does not unintentionally disengage the first end portion 23 of the adjacent secondary support member 17b.

The above steps are continued until a ladder 11 of the required length has been assembled.

To disassemble the ladder the latches 59 must be pushed towards each other such that the locking means 55 can be released from the aperture 51 and slot 49. This will allow the second end portion 25 to be slidingly released from the first end portion 23 of the adjacent secondary support member 17b allowing the release of the end 47 of the rung 15.

The secondary support members are constructed so as to provide a ladder of light construction whilst still providing the same, or greater strength and quality characteristics of ladders found in conventional assemblies.

The ladder components may be made from any suitable material which are selected depending on the application the ladder is to be used. For instance, the ladder may be made of a non-conductive material for electrical applications or may be made of a non-corrosive material for the use in areas where corrosion is a factor.

Each elongate element 13 may have at its respective ends a slightly modified secondary support member whereby, for instance, either the first end portion, in the case of the secondary support member at the top end of the elongate element, or the second end portion, in the case of the secondary support member at the bottom end of the elongate element, is not present. This provides the elongate element with structurally sound ends for positioning on or against a surface.

The applications of this type of ladder are widespread and include industries relating to water supply, drainage, rail and mining.

Modifications and variations such as that would be apparent skilled addressee are considered to fall within the scope of the present invention.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

The Claims Defining the Invention are as Follows

1. A ladder comprising a plurality of primary support members releasably supported in spaced apart relation by at least one elongate element, the at least one elongate element comprising a plurality of secondary support members adapted to slidingly engage each other in an end to end relationship to form the at least one elongate element.

2. A ladder according to claim 1 wherein each secondary support member is adapted to receive at least one of the plurality of primary support members.

3. A ladder according to claims 1 or 2 wherein there are two elongate elements.

4. A ladder according to claims 1 , 2 or 3 wherein each elongate element defines a side of the ladder and supports the plurality of primary support members therebetween.

5. A ladder according to any one of the preceding claims wherein each primary support element defines a rung to support a person using the ladder.

6. A ladder according to claim 5 wherein each secondary support member supports one end of one rung such that the length of each secondary support member determines the distance between adjacent rungs.

7. A ladder according to any one of the preceding claims wherein each secondary support member provides an inner face and an outer face.

8. A ladder according to any one of the preceding claims wherein each secondary support member comprises an elongate intermediate portion, a first end portion located at one end of the intermediate portion, and a second end portion located at the other end.

9. A ladder according to claim 8 wherein the first end portion comprises a neck portion extending from the intermediate portion, and a head portion extending from the neck portion and having a recessed portion therein adapted to releasably receive the end of the rung.

10. A ladder according to claim 9 wherein the neck portion extends substantially parallel to the longitudinal axis of the secondary support member.

11. A ladder according to claims 9 or 10 wherein the head portion extends from the neck portion, sloping away from the longitudinal axis and towards the intermediate portion, before extending away from the intermediate portion and taper towards the longitudinal axis of the secondary support member before terminating at a first edge substantially perpendicular to the longitudinal axis.

12. A ladder according to claims 9, 10 or 11 wherein the recessed portion extends inwardly from the inner face and terminates a predetermined distance from the outer face, such that it does not go beyond the outer face.

13. A ladder according to claims 11 or 12 wherein the recessed portion is open along the first edge of the first end portion such that an end of a rung is slidingly receivable in the recessed portion in a direction parallel with the longitudinal axis of the secondary support member.

14. A ladder according to any one of claims 8 to 13 wherein the second end portion comprises a cut out section.

15. A ladder according to claim 14 wherein the cut out section is contoured to slidingly receive the first end portion of an adjacent secondary support member in a direction transverse to the longitudinal axis, and providing a snug fit between adjacent secondary support members.

16. A ladder according to claims 14 or 15 wherein the second end portion also comprises a projection extending into the cut out section.

17. A ladder according to claim 16 wherein the projection extends a predetermined distance along the longitudinal axis of the secondary support member.

18. A ladder according to claims 16 or 17 wherein the projection extends in the transverse direction from the inner surface of the secondary support member and terminates a predetermined distance from the outer face.

19. A ladder according to claim 18 wherein the predetermined distance is substantially the same as the depth of the recessed portion located in the first end portion.

20. A ladder according to any one of claims 5 to 19 wherein each end of each rung has a slot in an upper surface.

21. A ladder according to claim 20 wherein the slot extends inwardly a predetermined distance from the end of the rung substantially parallel to the longitudinal axis of the rung.

22. A ladder according to claims 20 or 21 wherein the slot is adapted to receive the projection of the second end portion of the secondary support member.

23. A ladder according to any one of the preceding claims also comprising a plurality of locking means which, when the ladder is assembled, prevents adjacent secondary support members unintentionally disengaging from each other and releasing the primary support member.

24. A ladder according to claim 23 wherein each locking means is received in each end of each rung to prevent adjacent secondary support members disengaging.

25. A ladder according to any one of claims 20 to 24 wherein each end of each rung also comprises an aperture in communication with the slot.

26. A ladder according to claim 25 wherein the aperture extends from the slot through to the underside of the rung.

27. A ladder according to claims 25 or 26 wherein each locking means is adapted to be releasably retained in the aperture.

28. A ladder according to any one of claims 23 to 27 wherein each locking means comprises a tab section which is received in the slot and abuts the projection of the second end portion of the secondary support member, preventing it from disengaging the first end portion of the adjacent secondary support member when in an assembled condition.

29. A ladder according to claim 28 wherein each locking means comprises at least one latch extending laterally from the tab section, such that when assembled, the at least one latch engages an edge of the aperture to be releasably retained therein.

30. A ladder according to claim 29 wherein the at least one latch is resiliently flexible in a transverse direction.

31. A ladder according to claims 29 or 30 wherein the at least one latch engages an edge of the aperture to releasably retain the locking means therein.

32. A ladder according to claims 29, 30 or 31 wherein the locking means comprises two latches.

33. A ladder as substantially herein described with reference to the drawings.