AU779533B2

AU779533B2 - Levelling apparatus for a support structure

Info

Publication number: AU779533B2
Application number: AU16650/01A
Authority: AU
Inventors: Andrew Richards; Jon Scott
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-01-25
Filing date: 2001-01-25
Publication date: 2005-01-27
Anticipated expiration: 2021-01-25
Also published as: NZ527780A; EP1364106A4; EP1364106A1; AU1665001A; WO2002059446A1

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "LEVELLING APPARATUS FOR A SUPPORT STRUCTURE" The following statement is a full description of this invention, including the best method of performing it known to me/us: 2

TITLE

"LEVELLING APPARATUS FOR A SUPPORT STRUCTURE" FIELD OF THE INVENTION THIS INVENTION relates to a levelling apparatus for a support structure, for example a ladder or scaffold, on an uneven surface and method for attaching the levelling apparatus to the support structure.

BACKGROUND OF THE INVENTION Ladders and scaffolding are preferably used on a level surface for good stability. However, it is not uncommon to encounter situations where a surface is uneven or on an incline. Use of a ladder or scaffolding on such a surface may pose a danger to a person climbing the ladder or scaffolding. In some situations it may be possible to level the surface, for example, if the surface is dirt or gravel. However, levelling a ;dirt or gravel surface may be time consuming. In some situations the surface may not easily be levelled, for example concrete surfaces and steps. In the past, placing wood blocks or other objects as spacers under a ladder leg have been used to level the ladder. However, using such temporary means may be unsafe. To overcome this problem, ladders and S°apparatus for adjusting ladders to be level on uneven or sloping surfaces have been developed.

Levelling apparatus attachable to a ladder are described in US Patent Nos. 4,802,471; 5,335,754; 4,606,432 and 4,607,726. These patents relate to apparatus comprising an extension leg which may be extended and secured at different lengths.

3 US Patent No. 4,802,471 relates to an extendable leg which attaches to a lower end of a ladder side rail. The extendable leg when extended functions as a ladder support leg. The telescopic leg is securable at a desired extended length by using a gripping device having a sharp edge which locks an inner extendable rail relative to an outer rail.

The extendable leg is attached to the ladder by bolts which are fixed to the ladder side rail. Attaching this apparatus requires drilling of holes in the ladder side rail to accommodate the bolts.

US Patent No. 5,335,754 relates to a self-levelling ladder and to a leveller which may be attached to an existing ladder. The ladder leveller comprises a sleeve which slides over a bottom end of a ladder side rail. The sleeve functions as an extendable leg which extends away from the bottom end of the ladder side rail. When installing the ladder leveller to an existing ladder, an elongate slot is cut in each side rail 15 through which a bolt is fitted. The bolt may be horizontally slid within the °oooo slot to lock and unlock the sleeve at a desired extended length by engaging receiving notches on the sleeve.

US Patent No. 4,606,432 describes an adjustable ladder comprising a telescopic extension leg which may be attached to a ladder using clamping members adapted to fasten to a ladder side rail. The clamping members encircle the ladder side rail and are secured by bolts which fix the clamping members together.

US Patent No. 4,607,726 relates to a telescopic ladder leg extension apparatus which attaches to a bottom side rail of an existing 4 ladder. Two U-shaped notches receive adjacent ladder rungs respectively and with additional lock screws secure the apparatus to the ladder.

Apparatus for levelling ladders as described in US Patent Nos. 4,802,471 and 5,335,754 require additional equipment, time and skill to drill holes in existing ladder side rails. Such holes may weaken the ladder and reduce its structural integrity. US Patent Nos. 4,606,432 and 4,607,726 describe apparatus for levelling ladders which do not require drilling to attach to existing ladders; however, these apparatus use clamps which have multiple moving parts and may be complicated to manufacture and assemble.

SUMMARY OF THE INVENTION It is an object of the invention to provide a levelling apparatus to over come one or more of the limitations of, or improve 15 upon, the prior art as discussed above. The present invention provides a stable and simple means of attaching a levelling apparatus to a support structure and for levelling the support structure on an uneven surface.

In accordance with one aspect of the invention, a levelling apparatus for a support structure having one or more cross-members is provided, said levelling apparatus comprising an attachment means, which in use, extends at least partially through at least one of the one or more cross-members.

The attachment means may comprise one or more rods, shafts, dowels, spike or the like which extend through an interior of respective cross-members.

In one embodiment, the attachment means comprises one rod.

In another embodiment, the attachment means comprises two rods.

The attachment means may further comprise at least one stabilising means which partially extends within an interior of another respective cross-member.

Preferably, the levelling apparatus further comprises: a housing attachable to the support structure; and an inner member telescopically movable within the housing *eo.

and securable at a desired position relative to the housing; the housing being attachable to the support structure by said attachment means.

Preferably, the inner member is secured to the housing by a 15 locking means.

°eeoe Preferably, the locking means comprises a pin and a complementary aperture for securing the pin.

The invention also relates to a method of levelling a support structure having one or more cross-members including the step of attaching at least one levelling apparatus to the support structure wherein said levelling apparatus has attachment means which extends at least partially through at least one cross-member to level the support structure.

Preferably, the support structure comprises two parallel uprights and a plurality of horizontal cross-members therebetween.

6 The support structure may be a ladder or scaffold.

In use, two levelling apparatus may be attached to respective ground engaging ends of two parallel uprights of the support structure.

In use, one levelling apparatus may be attached to a ground engaging end of a parallel upright of the support structure.

A typical aluminum ladder has rungs which are spaced apart at a standard distance and usually have a hollow interior. The present invention is particularly useful with such an aluminum ladder; however, the invention may also be used with a ladder which is not provided with an existing hollow rung. For such a ladder, the ladder rung may be modified by creating an aperture through which the attachment rod of the invention may pass there through. Likewise, a scaffold may be modified to accommodate attachment of the present invention.

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

20 DESCRIPTION OF THE DRAWINGS In order that the invention may be readily understood and put into practical effect, preferred embodiments will now be described by way of example with reference to the accompanying drawings wherein like reference numerals refer to like parts and wherein: 7 FIG. 1 is a front view showing two levelling apparatus attached to and levelling a ladder; FIG. 2 is a side view of FIG. 1; FIG. 3 is a cross section of FIG. 2 as indicated; FIG. 4 is an exploded isometric view showing two levelling apparatus and a ladder; and FIG. 5 is an exploded isometric view showing another embodiment of a levelling apparatus in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a bottom part of a support structure, shown *oo.here as a ladder 50, comprising two parallel uprights or side rails 51 and 51a and cross-members or rungs 53 and 54 attached therebetween.

Levelling apparatus 10 and 10a are shown each comprising inner 15 members 14 and 14a which telescopically move within respective ooooo housings 16 and 16a. Levelling apparatus 10 and 10a attach to respective ladder side rails 51 and 51a. Levelling apparatus 10 and are mirror images of each other. Levelling apparatus 10 is adapted to :o ".attach to left side rail 51 and levelling apparatus 10a is adapted to attach 20 to right side rail 51a by an attachment means which extends through respective rungs 53 and 54.

Ladder 50 is shown levelled using levelling apparatus and 10a. Levelling apparatus 10 has inner member 14 telescopically retracted within housing 16 and levelling apparatus 10a has inner 8 member 14a telescopically extended out from housing 16. Inner members 14 and 14a are secured at a desired length relative to housing 16 by a locking means, shown as locking pin 13 and described in more detail hereinafter. In this configuration, right side of ladder 50 is supported by levelling apparatus 10a which contacts surface 30 at foot Ladder foot 52a is suspended and no longer engages surface Feet 15 and 15a are angled on their bottom surfaces to provide even contact with surface 30 when the ladder is angled or leaned against an object when in use as shown more clearly in FIGS. 2, 4 and 5. Feet and 15a may also be level and/or pivotable relative to inner members 14 and 14a.

Spacers 11 and 12 are integral to housing 16 and in use are located as shown between the outer side of side rails 51 and 51a and housing 16 of respective levelling apparatus 10 and 10a. Levelling apparatus 10 and 10Oa are attached to ladder 50 by an attachment means, shown as rod 17 (shown in FIGS. 3, 4 and 5) extending through an interior portion of respective rungs 53 and 54.

FIG. 2 shows a side view of levelling apparatus ~attached to right side rail 51a as shown in FIG. 1. Housing 16 of levelling apparatus 10a is attached to ladder 50 by extending rod 17 through respective rungs 53 and 54.

FIG. 3 is a cross-sectional view of ladder 50 and levelling apparatus 10 and 10a as shown in FIG. 2 at indicated arrows 3. FIGS. 3 and 4 more clearly show attachment of levelling apparatus 10 and 10a to 9 ladder 50 in an embodiment wherein two rods 17 extend through an interior of respective rungs 53 and 54. In another embodiment, a single rod 17 may be used. Rod 17 is shown as a threaded rod with bolt 18 attached at one end and secured at an opposite end by free bolt 19.

Other arrangements of rods and bolts may be used, for example a rod which is only threaded at opposite terminal ends and two free bolts fasten thereto. Also, the length of rod 17 may vary to accommodate different lengths of a rung or cross-member. It is understood that rod 17 may refer to an axle, shaft, wand, staff, pole, dowel, spike or other such member either hollow or solid and composed of any material. Preferably, rod 17 is solid metal.

As shown in FIGS. 3 and 4, to attach one embodiment of levelling apparatus 10 and 10a to ladder 50, two rods 17 are inserted through respective apertures 20 and 21 on housing 16 of levelling 15 apparatus 10a, through respective apertures on an outer side of side rail ooooo 51a aligned with rungs 53 and 54 (rungs shown with hollow interiors), and through corresponding respective apertures 20 and 21 on housing 16 of levelling apparatus 10 which is located adjacent to side rail 51. A second bolt 19 is threaded onto rod 17 to securely fasten housing 16 of levelling 20 apparatus 10 and 10a to opposite outer sides of ladder side rails 51 and 51a. Bolts 18 and 19 may be tightened using, for example, an extension socket spanner. Levelling apparatus 10 and 10a may be attached in a similar manner as described above, but inserting rod 17 in the opposite orientation passing first through levelling apparatus FIG. 4 also shows telescopic extension of inner members 14 and 14a within respective housings 16. A locking means is provided by locking pin 13 which is insertable into a complementary aperture 21 to secure inner member 14 or 14a at a desired length relative to housing 16.

To adjust inner member 14 and 14a to a different length, locking pin 13 is pulled outward and removed from complementary aperture 21 allowing inner member 14 or 14a to telescopically move within housing 16 to a new desire length. A plurality of complementary apertures 21 are linearly arranged along inner members 14 and 14a to provide different securable lengths. Locking pin 13 is inserted into complementary aperture 21 assisted by a force provided by a compression coil spring.

FIG. 5 shows another embodiment of levelling apparatus 110 and 110a whereby only a single rod 17 extends through a hollow interior of rung 53. In this embodiment, levelling apparatus 110 and 11 0a are stabilised by stabilising means 111 which is shown as a tapered projection which partially extends within an interior of rung 54. Stabilising means 111 may have other shapes which are at least partially insertable within a hollow interior of a rung or cross-member whereby in use stabilising means 111 prevents levelling apparatus 110 and 110 Oa from rotating around rod 17 which has been inserted through rung 53.

The present invention is not limited to the means described in the figures for adjusting and securing an extendable or telescopic member or leg. The abovementioned pin-and-aperture type locking mechanism is merely one method which may be used.. Other methods for 11 extending and securing extendable legs, for example those methods described in US Patent Nos. 4,802,471; 5,335,754; 4,606,432 and 4,607,726 may be used. The attachment means of the invention may also be used with a fixed leg which is not adjustable.

It is understood that a single levelling apparatus may be attached to a support structure, for example a single side rail of a ladder.

In this embodiment, the levelling apparatus is attached by extending one or more rods through a hollow interior of a ladder rung or scaffold member and securing an opposite end of the rod with a bolt or other suitable fastener. It may be necessary in provide a securing plate, which may for example be a washer or a flat metal plate, to provide a surface to prevent the bolt from pass through the hollow interior of the ladder rung or scaffold member.

Although the invention has been shown and described with 15 exemplary embodiments thereof, it should be understood by those skilled ooog• in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto without departing from the spirt and scope of the invention.

spirt and scope of the invention.

C.

C

Claims

1. A levelling apparatus for a ladder having a pair of side uprights and at least two hollow rungs, said apparatus comprising: a continuous tubular housing attachable to and spaced from said ladder, said tubular housing having a hollow interior of a length at least as long as a distance separating two adjacent ladder rungs; (ii) an inner member telescopically movable within the hollow interior of said housing and securable at a desired position relative to said housing, whereby said inner member telescopically moves parallel in relation to the side uprights of said ladder; (iii) an aperture located on the inner member; a mating securing pin located on the housing and insertable in the aperture in association with a spring providing bias on the 15 securing pin in a direction of insertion thereof; a spacer attached to the housing and locatable adjacent S:-i to a hollow rung of the ladder; and (vi) a threaded attachment member for attaching the housing to the ladder, 20 wherein the threaded attachment member is capable of ""*extending through the spacer and completely through an adjacent hollow rung of said ladder and is releaseably engaged to said housing.

2. The apparatus of claim 1 comprising a plurality of apertures located on the inner member.

3. The apparatus of claim 1 wherein the threaded attachment member is insertable through the housing.

4. The apparatus of claim 1 wherein the attachment member comprises a rod.

The apparatus of claim 1 comprising two attachment members.

6. The apparatus of claim 1 further comprising a stabiliser that extends only partially within an adjacent hollow rung. 13

7. A ladder assembly comprising: a ladder having a pair of side uprights and at least two hollow rungs; and at least one levelling apparatus comprising: a continuous tubular housing attachable to and spaced from said ladder, said tubular housing having a hollow interior of a length at least as long as a distance separating two adjacent ladder rungs; (11) an inner member telescopically movable within the hollow interior of said housing and securable at a desired position relative to said housing, whereby in use, said inner member telescopically moves parallel in relation to the side uprights of said ladder; (111) an aperture located on the inner member; inrbe (IV) a mating securing pin located on the housing and insertable in the aperture in association with a spring providing bias on the 15 securing pin in a direction of insertion thereof; a spacer attached to the housing and locatable adjacent to a hollow rung of the ladder; and (VI) a threaded attachment member for attaching the housing to the ladder, S 20 wherein the threaded attachment member is capable of extending through the spacer and completely through an adjacent hollow rung of said ladder and is releaseably engaged to said housing.

8. The ladder assembly of claim 7 comprising a plurality of apertures located on the inner member.

9. The ladder assembly of claim 7 wherein the threaded attachment member is insertable through the housing.

The ladder assembly of claim 7 comprising two attachment members.

11. The ladder assembly of claim 7 further comprising a stabiliser that extends only partially within an adjacent hollow rung. 14

12. The ladder assembly as claimed in claim 7 comprising a pair of said levelling apparatus.

13. A levelling apparatus for a ladder substantially as herein described with reference to the accompanying drawings.

14. A ladder assembly as herein described with reference to the accompanying drawings. 0 000 o* o* o o* *0 o* o *oo oooo*,* o *oo