WO2003080984A1

WO2003080984A1 - Improvements in or relating to ladders

Info

Publication number: WO2003080984A1
Application number: PCT/GB2003/001191
Authority: WO
Inventors: Roy Jones
Original assignee: Roy Jones
Priority date: 2002-03-19
Filing date: 2003-03-19
Publication date: 2003-10-02
Also published as: GB2402701A; AU2003229869A1; GB2402701B; GB0422923D0; GB0206438D0

Abstract

A safety device for use with a ladder (1) comprises a pair of support legs (6,7) pivotally connected to the stiles (2,3) of the ladder (1) and a pair of chains (16,17) extending between the support legs (6,7) and the ladder (1). The chains (16,17) are connected to each other via a fail-safe device operable if one of the chains breaks to maintain the support leg connected to the other chain operable. The pivotal connection of the support legs (6,7) may be provided through a hollow rung (4b) of the ladder (1) and the fail-safe device may connect the chains (16,17) through another hollow rung (4a) of the ladder (1).

Description

IMPROVEMENTS IN OR RELATING TO LADDERS

This invention concerns improvements in or relating to ladders. In particular, the invention concerns a safety device for supporting a ladder in use to prevent the ladder slipping.

According to a first aspect of the invention there is provided a ladder comprising a pair of stiles, a plurality of rungs extending between the stiles, a respective support leg pivotally connected to each stile and an elongate flexible retaining member connected to both legs and extending between the legs and the ladder for restricting pivotal movement of the legs relative to the ladder in use.

In use, the stiles, support legs and retaining member form a triangular structure in an operative position of the support legs in which both stiles and the support legs rest on the ground or other surface on which the ladder is placed to prevent the ladder from slipping.

Preferably, the retaining member is adjustable so that the operative position of the support legs can be adjusted to vary the inclination relative to the stiles according to the position of the ladder in use.

Advantageously, the retaining member comprises a pair of chains extending between the stiles and the support legs and linked by a fail-safe device operable if one of the chains breaks .

In one arrangement, the fail-safe device comprises a rigid rod located in a tube extending between the stiles and a pair of chains connected by the rod with each chain extending to a respective one of the support legs. With this arrangement, if one of the chains breaks, the rod is caused to jam in the tube by the force applied to the rod by the other chain.

The tube may comprise a hollow rung of the ladder and the support legs are preferably pivotally connected to the ladder via another hollow rung of the ladder. In this way, the safety device can be easily fitted to a ladder having hollow rungs, for example an aluminium ladder.

In another arrangement, the fail-safe device comprises a pair of eyebolts connected to each other and to the chains. The eyebolts may be connected to each other through a hollow rung of the ladder. With this arrangement, if one of the chains breaks, the eyebolts are prevented from passing through the hollow rung by the force applied by the other chain.

Preferably, each chain is releasably connectable to the associated support leg whereby the length of the chain can be adjusted to vary the maximum permitted angular movement of the support leg. In this way, the operative position of each support leg can be set according to the position of the ladder.

Advantageously, the safety device includes a lost motion connection.

Preferably, the support legs are pivotally connected to the ladder via a hollow rung of the ladder and each support leg is preferably pivotal between a stored position adjacent the stiles to an operative position extending at an angle to the stiles.

Advantageously, each support leg is provided with a support arm, the support legs and support arms being operable to restrain movement of the ladder in mutually perpendicular directions. Each support arm may be foldable from a stored position to an operative position and is braced and retained in the operative position by a strut extending between the support arm and the support leg.

According to a second aspect of the invention there is provided a safety device for use with a ladder, the device comprising at least two legs connectable to the ladder through a hollow rung of the ladder for pivotal movement relative to the ladder and an elongate flexible retaining member connected to the legs and arranged, in use, to be passed through another hollow rung of the ladder.

The safety device can be fitted to a ladder having hollow rungs without modifying the ladder. The safety device can be supplied fitted to a ladder or it can be supplied separately for retro-fitting to a ladder. The safety device can be fitted in a very simple manner without special tools or skills, for example by a non-skilled person such as a DIY enthusiast.

According to a third aspect of the invention, there is provided a safety device for use with a ladder, the device comprising a pair of support legs connectable to respective stiles of the ladder adjacent to a lower end of the ladder for pivotal movement relative to the ladder between operative and inoperative positions and elongate flexible retaining members extending between the support legs and the stiles to secure the support legs in the operative position.

Other features and advantages of the invention will be apparent from the following description of an embodiment of the invention given, by way of example only with reference to the accompanying drawings, in which:- Figure 1 shows a side view of a ladder according to a first embodiment of the invention, in use, with the safety device in an operative position;

Figure 2 shows a perspective view of a lower portion of the ladder of Figure 1 ;

Figure 3 shows an enlarged side view of a lower portion of the ladder of Figure 1 ;

Figure 4 shows a retaining member of the safety device shown in Figures 1 to 3;

Figure 5 shows a pivotal attachment means of the safety device shown in Figures 1 to 3;

Figure 6 shows a perspective view of a ladder according to a second embodiment of the invention, in use, with the safety device in an operative position;

Figure 7 shows the retaining member of the safety device shown in Figure 6;

Figure 8 shows a modification to the safety device shown in Figure 6; and

Figure 9 shows a perspective view of a ladder according to a third embodiment of the invention, in use, with the safety device in an operative position. With reference to Figures 1 to 5 of the accompanying drawings, a ladder 1 according to a first embodiment of the invention is shown comprising a pair of stiles 2, 3 extending parallel to each other and a plurality of hollow rungs 4 extending between the stiles 2, 3.

In this embodiment the stiles 2, 3 and rungs 4 are made of aluminium, but it will be understood that the stiles 2, 3 and rungs 4 can be made of any other suitable material. The rungs 4 are integrally connected to the stiles 2, 3 such that the hollow interior of the rungs 4 is accessible from the outwardly directed sides of the stiles 2, 3.

A safety device 5 for the ladder 1 comprises a pair of support legs 6 and 7 attached in a pivotal manner to the stiles 2 and 3 respectively by attachment means 8 and a retaining member 9 extending between the legs 6 and 7 through the first rung 4a of the ladder 1. The legs 6 and 7 are made of aluminium, but it will be understood that any other suitable material may be used.

The attachment means 8 comprises a bolt 13 having threaded ends and nuts 14 having clover shaped heads. The bolt 13 passes through the second rung 4b of the ladder 1 and the threaded ends are received in through bores in the upper ends of the legs 6 and 7. The nuts 14 screw onto the ends of the bolt 13 to secure the legs 6 and 7 to the ladder 1. The nuts 14 can be tightened by hand.

In a modification (not shown) , the length of the bolt 13 may be adjustable for connecting the legs 6, 7 to ladders of different width. For example, the bolt 13 may comprise threaded end portions engageable with an internally threaded centre sleeve whereby the projecting length of the end portions can be adjusted according to the width of the ladder. Alternatively, one end portion may have a threaded socket engaged by the other end portion whereby the length of the bolt can be adjusted.

The retaining member 9 consists of two chains 15, 16 connected by a metal rod 17. Each chain 15, 16 is provided at the free end with a clip 18, 19 respectively. In a different arrangement (not shown) the chains 15, 16 are replaced with a flexible strap.

The rod 17 is positioned in the first rung 4a of the ladder 1 and the chains 15 and 16 extend from opposite ends of the rung 4a and are connected to the legs 6, 7. Each chain 15 and 16 passes through a respective loop 20 secured to the legs 6, 7 to extend back upon itself such that clip 18 or 19 can be hooked onto a link of the chain 15 or 16 respectively.

In this way, the length of the chains 15, 16 between the stiles 2, 3 and the legs 6, 7 is adjustable. The length of the chains 15 and 16 defines the operative position of the legs 6, 7 in use and is adjustable to ensure both legs 6, 7 rest on the ground or similar surface on which the ladder is placed so that the legs 6, 7 are inclined in the opposite direction to the stiles 2, 3.

In a different arrangement (not shown) , the loops 20 and clips 18 and 19 are replaced by toggles attached to the legs 6,7 and the chains 15 and 16 have links attachable to the toggles such that their lengths are adjustable.

In use, the safety device 5 prevents the ends of the stiles 2 and 3 from slipping in the direction of arrow A away from a wall 21 or the like against which the upper end of the ladder is placed. Thus, a downwards force in the direction of arrow B produced by a person on the ladder that tends to cause the stiles 2, 3 to slip in the direction of arrow A will be resisted by pivotal movement of the legs 6, 7 in the direction of arrow C to tension the chains 15 and 16. The legs 6 and 7, stiles 2 and 3 and retaining member 9 therefore form a rigid triangular structure preventing any further movement of the stiles 2 and 3 in the direction of arrow A.

If one of the chains 15 or 16 breaks, the metal rod 17 is twisted and frictionally engages the interior walls of the hollow rung 4a in response to the force applied to it by the other chain. In this way, the safety device remains operative on one side of the ladder in a fail-safe manner to prevent the ladder slipping if one of the chains 15 or 16 breaks.

The safety device 5 may be set up to leave a small amount of slack or play in the chains 15, 16 so that movement of a person up and down the ladder in normal use does not create high loads on the chains 15,16. In this way, the risk of the chains 15, 16 breaking, for example due to normal flexing (bounce) of the ladder, is reduced but, if the ladder 1 starts to slip, the slack or play is taken up and the chains 15,16 tensioned to lock the legs 6,7 in position. As a result, the ladder 1 is prevented from slipping.

In a modification (not shown) , the retaining member 9 may be protected by a lost motion connection that compensates for normal flexing (bounce) of the ladder 1 in use. For example, the rod 17 may comprise two parts spring loaded to a retracted position that allows the length of the rod 17 to increase under axial loading such as when the chains are subjected to a tension force.

In this way, the safety device 5 can be set up with the rod 17 in the retracted position and loads applied to the chains 15,16 during normal use as a person moves up and down the ladder 1 are taken up by the spring loading of the rod 17. If the applied load exceeds the permitted increase in length of the rod 17, for example if the ladder 1 starts to slip, the chains 15,16 are tensioned to lock the legs 6,7 in position. As a result, the ladder 1 is prevented from slipping.

It will be understood that other arrangements for providing lost motion may be provided to protect the chains 15,16. For example, the clips 18,19 and/or the loops 20 for securing the ends of the retaining member 9 may incorporate spring loading that compensates for flexing (bounce) of the ladder 1 during normal use.

The safety device 5 can be provided as a kit separate from the ladder 1 such that it can be retro-fitted to existing ladders 1 having hollow rungs 4. Assembly of the safety device 5 is easy as there is no need to modify the existing ladder 1 and no special tools or skills are required to fit the safety device 5.

As will be appreciated, by providing the retaining member as an elongate flexible member connectable at opposite ends to both support legs and passing a centre section through a hollow member associated with the ladder, installation and set-up of the safety device is simplified.

Referring now to Figures 6 and 7 of the accompanying drawings, a ladder according to a second embodiment of the invention is shown. For convenience like reference numerals in the series 100 are used to indicate parts corresponding to the first embodiment.

In this embodiment, the rodl7 connecting the chains 115, 116 is replaced by male and female eye bolts 130, 131. The male eye bolt 130 has an externally threaded shank 132 and the female eye bolt 131 has a matching internally threaded sleeve 133 for screw threaded engagement of the shank 132.

Each bolt 130, 131 has a retainer ring 134, 135 respectively at one end and an adjacent annular washer 136,137 respectively. The chains 115, 116 are connected at one end to the retainer rings 134, 135 respectively and the other end is passed through a loop 120 on the associated support leg 106,107 and back on itself to be secured to a link of the chain 115,116 or to the retainer ring 134, 135.

In use, the eye bolts 130, 131 are inserted into opposite ends of a hollow rung 104a of the ladder 101 and the shank 132 of the male bolt 130 screwed into the sleeve 133 of the female bolt 131 until the washers 136,137 locate against the outer faces of the stiles 102, 103. In a modification (not shown) , a pair of male eyebolts may screw into opposite ends of a threaded sleeve between the stiles .

The support legs 106,107 are pivotally attached to the stiles 102, 103 as described previously and the chains 115, 116 secured to permit pivotal between an inoperative stored position adjacent to the stiles 102,103 and an operative position extending at an angle to the stiles 102, 103 as shown in Figure 6. The length of the chains may be adjustable as described previously to allow the operative position of each support leg 106, 107 to be adjusted independently according to the position of the ladder 101.

In use, if one of the chains 115,116 breaks, the washers 136, 137 prevent the eye-bolts 130, 131 being pulled through the rung 104a by tension in the other chain and the associated support leg remain operable in a fail- safe manner to prevent the ladder 101 slipping in the direction of arrow A away from the wall 121.

The safety device may be set-up with limited slack in the chains 11 ,116 to compensate for normal flexing (bounce) of the ladder in use. Alternatively, a lost motion connection may be incorporated for this purpose as described previously.

As will be appreciated, the safety device of Figures 6 and 7 can be fitted to a ladder during manufacture or provided as a kit to be retro-fitted to a ladder with hollow rungs in similar manner to the first embodiment and the eye bolts 130, 131 enable the safety device to be fitted to different widths of ladder 101.

Referring now to Figure 8, there is shown a modification to the security device of Figures 6 and 7. For convenience, like reference numerals in the series 200 are used to indicate corresponding parts.

In this embodiment, the support legs 206,207 are provided with stabilising arms 240,241 respectively to prevent sideways movement of the ladder 201. The arms 240,241 are foldable from a stored position (not shown) alongside the support legs 206,207 to an operative position as shown in which the arms 240,241 extend substantially normal to the support legs 206,207 on either side of the ladder 201. The arms 240,241 are releasably secured in the operative position by struts 242,243 that are attached at one end to the arms 240,241 and clip to the support legs 206,207 at the other end to brace and retain the arms 240,241 in the operative position. In use, the support arms 240,241 resist sideways movement of the ladder 201. In this way, the safety device secures the bottom end of the ladder 201 against movement in the direction of arrow A away from the wall 221 and the direction of arrow D substantially parallel to the wall 221.

Referring now to Figure 9 of the accompanying drawings, there is shown a ladder according to a third embodiment of the invention. For convenience, like reference numerals in the series 300 are used to indicate corresponding parts.

In this embodiment, the ladder 301 is made of wood and the support legs 306,307 are mounted on the stiles 302,303 by drilling aligned holes in each stile 302,303 and pivotally connecting the legs 306,307 to the stiles through the holes. Alternatively, the legs 306,307 may be attached to opposite ends of a rod extending between the stiles 302,303. The rod may be housed in a hollow tube extending between the stiles 302,303.

Each leg 306,307 is pivotal between a stored position (not shown) adjacent to the stiles 302,303 and an operative position extending at an angle to the stiles 302,303 as shown. The legs 306,307 are retained in the operative position by chains 315,316 extending through holes 350,351 respectively in the legs 306,307 and secured to separate eyebolts 352 (one only shown) attached to the stiles 302,303.

In use, if one of the chains 315,316 breaks, the support leg connected to the other chain remains operable to prevent the ladder 301 slipping in the direction of arrow A as described previously.

In a modification (not shown) , the separate eyebolts 352 are replaced by the male and female eyebolts shown in Figure 7 and aligned holes are drilled in the stiles 302,303 to allow the male and female eyebolts to be connected together. Alternatively, an internally threaded sleeve may be provided between the stiles 302,303 and a pair of male eyebolts screwed into opposite ends of the sleeve through the stiles.

In another modification (not shown) , aligned holes are drilled in the stiles 302,303 to receive a hollow tube extending between the stiles 302,303 and the chains 315,316 are connected to each other via a rod located in the tube. This arrangement operates in similar manner to the first embodiment with the rod becoming jammed in the tube if one of the chains breaks so that the support leg connected to the other chain remains operable to prevent the ladder slipping.

It will be understood that the invention is not limited to the above-described embodiments and that various modifications and improvements can be made within the scope of the invention described herein.

For example, where the ladder has hollow rungs, the safety device may be fitted to the ladder using the bottom two rungs as described or any other combination of the rungs. The safety device may be adjustable for mounting the device on ladders of different width. In this way, the safety device may have universal application to a range of ladder types and sizes.

Although the safety device has particular application for ladders with hollow rungs, it will be appreciated that the safety device can be fitted to ladders with solid rungs by employing opposed holes in the ladder stiles to mount the device. The support legs may be separate from each other and pivotal independently as described and illustrated. Alternatively, the support legs may be interconnected and pivotal together. In this arrangement, the failsafe device will operate to maintain the position of both legs if one chain breaks.

Furthermore, it will be understood that features of any of the embodiments may be combined with features of any other embodiment and the invention includes all combinations of any features described herein.

Claims

1. A ladder comprising a pair of stiles, a plurality of rungs extending between the stiles, a respective support leg pivotally connected to each stile and an elongate flexible retaining member connected to both legs and extending between the legs and the ladder for restricting pivotal movement of the legs relative to the ladder in use.

2. A ladder according to claim 1 wherein, in use, the stiles, support legs and retaining member form a triangular structure in which both stiles and the support legs rest on the ground or other surface on which the ladder is placed to prevent the ladder from slipping.

3. A ladder according to claim 2 wherein, the retaining member is adjustable so that inclination of the support legs relative to the stiles can be adjusted according to the position of the ladder in use.

4. A ladder according to any one of the preceding claims wherein, the retaining member comprises a pair of chains extending between the stiles and the support legs and linked by a fail-safe device operable if one of the chains breaks.

5. A ladder according to claim 4 wherein, the fail-safe device comprises a rod located in a hollow tube between the stiles and connected at opposite ends to the chains such that, in use, if one of the chains breaks, the rod is caused to jam in the tube by the force applied to the rod by the other chain.

6. A ladder according to claim 5 wherein the tube comprises a hollow rung of the ladder

7. A ladder according to any one of claims 3 to 6 wherein, each chain is releasably connectable to the associated support leg whereby the length of the chain can be adjusted to vary the maximum permitted angular movement of the support leg.

8. A ladder according to claim 4 wherein the fail-safe device comprises a pair of eyebolts connected to each other and to the chains.

9. A ladder according to claim 8 wherein the eyebolts are connected to each other through a hollow rung of the ladder.

10. A ladder according to any one of claims 4 to 9 wherein the safety device includes a lost motion connection.

11. A ladder according to any one of the preceding claims wherein the support legs are pivotally connected to the ladder via a hollow rung of the ladder

12. A ladder according to any one of the preceding claims wherein each support leg is pivotal between a stored position adjacent the stiles to an operative position extending at an angle to the stiles.

13. A ladder according to any one of the preceding claims wherein each support leg is provided with a support arm, the support legs and support arms being operable to restrain movement of the ladder in mutually perpendicular directions.

14. A ladder according to claim 13 wherein each support arm is foldable from a stored position to an operative position and is braced and retained in the operative position by a strut extending between the support arm and the support leg.

15. A safety device for use with a ladder, the device comprising at least two legs connectable to the ladder through a hollow rung of the ladder for pivotal movement relative to the ladder and an elongate flexible retaining member connected to the legs and arranged, in use, to be passed through another hollow rung of the ladder.