GB2548130A

GB2548130A - Levelling device for a ladder

Info

Publication number: GB2548130A
Application number: GB1604064.4A
Authority: GB
Inventors: Radford Alan; Wedlake Ian
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-03-09
Filing date: 2016-03-09
Publication date: 2017-09-13
Also published as: GB201604064D0

Abstract

A levelling device 1 has a base member 2 comprising an arcuate guide-rail extending between a pair of support feet 3, 4. A pair of roller assemblies 5, 6 are coupled to the lower ends of the ladder side rails S1, S2 such that they can move along the guide-rail. Locking means 7, 8 secure to at least one roller assembly to releasably secure it at a desired position. The device may include box portions for receiving the side rails of the ladder. The roller assemblies may include a pair of arms located on opposite sides of the guide-rail. The locking means may include means for drawing the side arms into clamping arrangement with the guide rail and may optionally include a pin extending between said side arms.

Description

LEVELLING DEVICE FORA LADDER

TECHNICAL FIELD OF THE INVENTION

This invention relates to a device for levelling a ladder to attain a stable condition when the ladder is used on an uneven surface.

BACKGROUND

Ladder levelling devices of the kind by which one or both side rails of a multi-rung ladder can be extended at their lower ends to stabilise the ladder on a sloping, irregular or uneven surface are well known. It is also known to provide additional stabilising legs which extend outwards and downwards at the bottom end of the ladder to provide lateral support against sideways movement and increase stability. Such known ladder levelling devices generally require manual manipulation of the devices while the ladder is in a vertical position. The process by which correct adjustment is arrived at often involves a great deal of trial and error which is both tedious and time consuming, and there is a risk that users who are in a hurry may accept a condition which is considered to be "near enough", with a possibility of disastrous consequences.

The present invention seeks to provide a new and inventive form of ladder levelling device which is quick and simple to adjust whilst at the same time providing enhanced stability.

SUMMARY OF THE INVENTION

The present invention proposes a levelling device for a ladder having rungs extending between a pair of side rails with respective lower ends, said device comprising: - an base member incorporating a guide-rail of arcuate shape extending between a pair of support feet to rest on a surface; - a pair of roller assemblies coupled one to each of the lower ends of the ladder side rails such that the roller assemblies can move longitudinally along the guide-rail whereby the rungs of the ladder can be adjusted to a substantially level condition; and - locking means for releasably securing at least one of said roller assemblies to the guide-rail when the ladder has been adjusted to the desired condition.

The invention also provides a ladder levelling device with roller assemblies which include box portions for receiving the side rails of the ladder.

The invention also provides a ladder levelling device with roller assemblies which include a pair of side arms located on opposite sides of a guide-rail.

The invention also provides a ladder levelling device with locking means which includes means for drawing side arms into clamping engagement with a guide-rail.

The invention also provides a ladder levelling device with a roller assembly which includes a pin which extends between side arms.

The invention also provides a ladder levelling device with a pin which carries a cam operated by a locking lever.

The invention also provides a ladder levelling device with a pin which carries at least one rotatable roller to move along a guide-rail.

The invention also provides a ladder levelling device with a guide-rail which has a pair of parallel runners separated by an rib.

The invention also provides a ladder levelling device with a pin which carries a pair of rotatable rollers arranged to move along runners on opposite sides of a rib.

The invention also provides a ladder levelling device with arms having projections which locate beneath runners.

The invention also provides a ladder levelling device with support feet which have ball connections with a guide-rail.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a general view of a ladder levelling device;

Figure 2 is a side view of the base member of the ladder levelling device;

Figure 3 is a cross-section through the base member taken on the plane A-A of Fig. 2;

Figure 4 is a further cross-section through the base member, including one of the roller assemblies of Fig. 1;

Figure 5 is a side view of the roller assembly and part of the base member;

Figure 6 is a general view of a housing of the roller assembly; and

Figure 7 is a schematic side view of the ladder levelling device to demonstrate how the device adapts to sloping or uneven ground.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig. 1, the ladder levelling device 1 is intended for use at the lower end of a ladder L having rungs R extending between a pair of side rails, or styles, SI and S2. The levelling device includes a base member 2 with a pair of support feet 3 and 4, and a pair of roller assemblies 5 and 6, provided with locking levers 7 and 8, supporting the lower ends of the respective side rails SI and S2.

Referring to Fig. 2, the base member 2 includes a guide-rail 10 which is formed on a curve, preferably a part-circular arc, provided at both ends with socket blocks 11 and 12 in which the respective support feet 3 and 4 are mounted. Referring to Fig. 3, the guide-rail 10 is of uniform cross-section, being of cruciform shape with a pair of side runners 14 and 15 extending on opposite sides of a bottom strengthening limb 16 and a guide rib 17 projecting upwardly between the runners. The support feet 3 and 4 may be of circular profile, each having a bottom layer 23 which has a textured or friction-grip undersurface. The top of each foot has a central mounting spigot 24 for reception in the respective socket block 11, 12. The spigot 24 may incorporate a ball joint to enable the underside of each foot to better adapt to the contour of a surface on which it stands, thereby ensuring an even better grip.

Turning now to Fig.s 4 to 6, each of the roller assemblies 5, 6 incorporates a roller assembly housing 30 having an open-topped box section 31 dimensioned to closely receive the bottom end of a respective side rail SI or S2. A pair of side plates 32 and 33 depend from opposite sides of the box section 31 ending in in-turned flanges 34 and 35. A headed pin 36 extends through the side plates 32 and 33 to rotatably receive a pair of rollers 37 and 38 separated by a spacer 39. The guide-rail 10 is received between the side plates 32 and 33. The flanges 34 and 35 locate beneath the runners 14 and 15 to retain the assembly on the guide-rail 10. The rollers 37 and 38 rest on the runners 14 and 15 on opposite sides of the guide rib 17. A projecting end of each pin 36 is pivotably connected to a respective locking lever, 7 or 8, and each locking lever has a cam face 42 opposed to one of the side plates 33. When each locking lever is in a lowered (released) position as shown in Fig. 1 the rollers are free to rotate allowing the whole roller assembly to travel smoothly along the guide-rail 10. However, when the levers are moved to a raised (locked) position as in Fig. 4 the side plates 32 and 33 are drawn slightly together causing them to grip the outer faces of the runners 14 and 15, firmly clamping the roller assemblies to the guide-rail 10. When the side plates are drawn together they may also act on the rollers 37 and 38 causing them to frictionally engage the side plates and the central rib 17, further reducing the risk of movement along the guide-rail.

As advantage of arranging the locking levers 7 and 8 to lock the rollers when raised is that an additional latch (not shown) can be provided to hold the lever to the adjacent side plate 33, thereby providing an additionai safeguard against accidentai reiease. It wiii however be appreciated that the ievers couid be arranged to iock in any convenient rotationai position.

Aithough it wouid be possibie for the side raiis SI and S2 to be a ioose fit in the box sections 31 of the roiier assembiies, for safety and generai convenience it is preferred to attach the roiier assembiies to the side raiis, e.g. by means of boits 45 and 46.

Fig. 7 iiiustrates schematicaiiy how the ieveiiing device allows a ladder to be placed stably on sloping or uneven ground with one of the feet 3, 4 higher than the other. By moving the locking levers 7 and 8 to their reieased position the roller assemblies can be moved smoothiy aiong the guide-rail 10 until the side rails SI and S2 become vertical. At least one of the levers, and preferably both, are then pivoted into a iocked position so that the ladder cannot move along the guide-rail. With a iittie practice the locking levers could easily be operated by foot leaving the users hands free to hoid and manipuiate the iadder.

Typicaiiy, for a 600 mm iong base member 2 with a height of about 120 mm, the device can accommodate a height difference h of up to 120 mm between the feet 3 and 4, which is ample for safe conditions of use. Since the spacing between the feet 3 and 4 is greater than between the side raiis of the iadder the setup is inherentiy more stabie than using a iadder on its own, even on ievei ground.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

Claims

1. A levelling device for a ladder having rungs extending between a pair of side rails with respective lower ends, said device comprising: - an base member incorporating a guide-rail of arcuate shape extending between a pair of support feet to rest on a surface; - a pair of roller assemblies coupled one to each of the lower ends of the ladder side rails such that the roller assemblies can move longitudinally along the guide-rail whereby the rungs of the ladder can be adjusted to a substantially level condition; and - locking means for releasably securing at least one of said roller assemblies to the guide-rail when the ladder has been adjusted to the desired condition.

2. A levelling device according to Claim 1 in which the roller assemblies include box portions for receiving the side rails of the ladder.

3. A levelling device according to Claim 1 or 2 in which the roller assemblies include a pair of side arms located on opposite sides of the guide-rail.

4. A levelling device according to Claim 3 in which the locking means includes means for drawing the side arms into clamping engagement with the guide-rail.

5. A levelling device according to Claim 3 or 4 in which each roller assembly includes a pin which extends between the side arms.

6. A levelling device according to Claim 5 in which the pin carries a cam operated by a locking lever.

7. A levelling device according to Claim 5 or 6 in which each pin carries at least one rotatable roller to move along the guide-rail.

8. A levelling device according to any preceding claim in which the guide-rail has a pair of parallel runners separated by a rib.

9. A levelling device according to Claim 5 and 8 in which the pin carries a pair of rotatable rollers to move along the runners on opposite sides of the rib.

10. A levelling device according to Claims 3 and 8 in which the arms have projections which locate beneath the runners.

11. A levelling device according to any preceding claim in which the support feet have ball connections with the guide-rail.

12. A levelling device substantially as described with reference to the drawings.