GB2432394A

GB2432394A - A ladder safety device

Info

Publication number: GB2432394A
Application number: GB0622884A
Authority: GB
Inventors: Michael John Stephens; Christopher Price; Terence James Scarfe
Original assignee: Forest Safety Products Ltd
Current assignee: Forest Safety Products Ltd
Priority date: 2005-11-17
Filing date: 2006-11-16
Publication date: 2007-05-23
Also published as: GB0523425D0; GB0622884D0

Abstract

A ladder safety device 10 for securing a ladder 50 to a structure against which the ladder is placed comprises a means 20 for securing the device to the structure and means for restraining the movement of the ladder 50 at least in one direction relative to the structure, the restraining means includes at least one member 30 which is displaceable between an in operative position and an operative position where it prevents the movement of the ladder. The invention seeks to prevent the ladder twisting or slipping in use. A further embodiment discloses the automatic engagement of the restraining means when the ladder is placed against it.

Description

I

A LADDER SAFETY DEVICE

The present invention relates generally to a ladder safely device.

Although ladders are widely used for access to elevated locations there continue to be safety problems due primarily to the risk of slipping at the foot, outwards away from the structure against which the ladder is placed, with accompanying sliding of the top of the ladder down the structure. A secondary problem occurs with potential lateral displacement of the top of the ladder, especially when a user is stretching to reach sideways to a remote location. Other problems arise when the feet of the ladder are not placed firmly on secure ground, allowing a measure of : twisting to occur if one foot, for example, is held spaced from sloping ground or uneven terrain.

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* Despite the awareness of these risks a number of accidents continue to occur, *..* * . resulting in more or less serious injuries. Health and Safety Regulations governing the use of ladders are likely to be made more stringent in the future with the increasing reluctance to place employees at risk. Even when ladders have been positioned relatively securely, accidents can still happen where workers have their attention elsewhere, perhaps because they are carrying a load or concentrating on the tasks with which they are occupied. All of these risks result from the fact that ladders are generally simply placed against the structure to which they are used for gaining access so that both the foot and the top of the ladder are unrestrained and capable of displacement.

Previous attempts to increase ladder safety have concentrated on the foot. It is known to provide stabiliser legs attachable to the lower part of the ladder stile and projecting laterally and forwardly away from the stile to provide a further support.

It is also known to place wedges under the feet of ladders placed on sloping or uneven terrain. Although these devices are available they have the drawback that they must all be fitted and used carefully and their function monitored. Even when available such devices are sometimes not employed simply because the ladder user is too busily occupied with the tasks in hand for which the ladder is simply an adjunct allowing access to be gained to the location at which the task is to be undertaken. * S. * . S *5*S

The present invention makes a new approach to this problem by providing means, which can improve ladder safety without requiring conscious actions by the user.

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* Moreover, where in the prior art attention has been concentrated at the foot of the *5 * ladder, the present invention is based on the realisation that action taken at the top * . of the ladder can provide equal safety and has substantial advantages in terms of ease of use and certainty of engagement. Security provisions made at the top of a ladder (or, more precisely, in the upper region of the ladder since it may not be precisely at the very top) still allow the ladder to be used on sloping or uneven terrain with equal safety although if one stile is entirely spaced from sloping or uneven ground it may be appropriate to fit wedges in position to help to prevent ladder twisting movements as the user stands on the lower rungs.

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In one aspect, the invention provides a ladder safety device for securing a ladder to a structure against which the ladder is placed having means for securing the device to the structure and means for restraining the movement of the ladder at least in one direction relative to the structure, said means including at least one member which is displaceable between an operative position in which it restrains the movement of the ladder and an inoperative position.

The said one direction may be laterally of the ladder or downwards, and it is preferred that the restraining means acts to restrain the movement of an upper part of the ladder laterally in a direction generally parallel with the ground. With such an arrangement, even if the foot of the ladder is placed on inadequately secure ground and may be liable to slip, the fact that the top of the ladder is restrained : ::: against lateral movement will mean that such slippage of the foot of the ladder and S....' consequential twisting and/or sideways movement of the ladder will not take place * : 15 and the ladder will be secure in position against the structure. Such an arrangement also prevents a ladder from moving laterally caused by a user leaning out sideways, possibly in an effort to reach something, and over-balancing.

The restraining means may, however, act to restrain turning movement of an upper part of the ladder rather than linear displacement, and this will have substantially the same effect since outward slipping at the foot of a ladder has to be accompanied not only by downward movement of the top of the ladder, but also rotation of each part of the ladder about a horizontal axis. By preventing such rotation the potential slippage at the foot and top of the ladder can likewise also be resisted.

Although the device has been described above with regard to a ladder lying at an angle to the structure against which it is placed the ladder could equally lie parallel to the structure such that, for example, in use with a scaffold it lies substantially vertically. Further, the ladder does not have to have one end resting on the ground.

Rather, the ladder could be secured to the scaffold at the upper end and hang free at the lower end. Alternatively, another device could be used to secure the lower end to the scaffold.

In one embodiment of the invention the at least one member is substantially linearly displaceable between its operative and inoperative positions. This could take the form of the member sliding with respect to the device such that in the IS operative position the at least one member is extended with respect to the device * and in the inoperative position the at least one member is retracted with respect to S. S * . the device. S* * * S S * S.

The retracted position of the movable member allows the ladder to be placed in position, or removed. When the movable member is displaced to its operative position, however, it acts to restrain the movement of the ladder in one or more ways as discussed above.

Alternatively, the at least one member may be displaced from its inoperative to its operative position, and vice-versa, by rotary motion, such rotary motion involving turning of the member about an axis in order to vary its orientation, or turning movement about an axis spaced from the at least one member such that it S effectively orbits, at least partially, about the axis around which it turns. The rotary movement has the effect that in the operative position the at least one member protrudes from the device and in the inoperative position it lies substantially within the device.

In a preferred embodiment of the invention the device is adapted to fit between the stiles of a ladder such that in the operative position the at least one member lies transversely across the at least one stile such that the at least one stile is trapped :.:::. between the at least one member and the structure against which the ladder is placed. The body of the device may itself also act to restrain the stile against movement in certain directions, particularly laterally.

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: * . In one embodiment the at least one member is adapted to move from its operative

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: position to its inoperative position by the pressure of the ladder stile against it.

In a preferred embodiment the at least one member is rigid.

Once the ladder has been placed in position with the device, the member is moved to its operative position such that the movement of the ladder is restrained. The member may be biased towards its operative position to aid the operation of the device such that once a ladder has been positioned in the correct place the member automatically moves to its operative position. This may be achieved by resilient means, such as a spring, by the effect of gravity on the member, or by means of a counterweight and pivot.

An additional feature, which the device may have incorporated, is the means for locking the member in either or both of its inoperative and operative positions.

This means could take the simple form of holes in the housing of the device being aligned with corresponding holes in the member such that a bolt or padlock may be placed through the aligned holes to restrain the movement of the member with respect to the housing and thus hold it in either the operative and/or inoperative positions. * *. * * . S... *5S*

To improve the ease with which the device may be used it could further include means for attaching it to structures against which it will be placed. For instance, if * * for use with scaffolding the device could incorporate scaffold clamps. However, S. S :: although scaffolds have been discussed it should be understood that the device * . could be used with any structure to which it could be securely attached, for instance, trees, walls, window frames or ledges, towers, pylons etc. In each case the means of attachment may have to be adapted to suit the conditions.

In one embodiment, the device includes an upper surface and scaffold clamps located on the back wall. The position of the clamps relative to the upper surface is selected so that, in use, the upper surface is positioned at substantially the same

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horizontal level as the upper surface of an adjacent deck board supported, at least in part, by the section of scaffolding to which the device is attached.

In another aspect, the invention provides a method of retaining a ladder in a working position placed against a fixed structure by restraining the movement of the ladder by at least one member.

In a further aspect, the invention provides a ladder safety device having means for restraining the ladder against displacement in at least one direction, in which engagement of the restraining means is effected automatically upon placement of the ladder there against.

The present invention also comprehends a method of securing a ladder in a working position placed against a fixed structure by restraining the movement of the upper part of the ladder by releasable retainer means. * * ** *

: * ** In a yet further aspect therefore, the invention provides a method comprising the S. S * .: steps of placing the ladder in position against a structure in engagement with a housing which restrains lateral movement of the ladder, positioning at least one rigid restraining member over one and preferably both stiles in a position such as to restrain movement of the ladder away from the said structure, and repositioning the foot of the ladder to take up any clearance between the ladder stile or stiles and the restraining member.

Various embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of one embodiment of the device; Figure 2 is a cross-section through Figure 1 along line fl-il; Figure 3 is a plan view of a different embodiment of the device; Figure 4 is a cut-away side view of the device of Figure 3 in the operative position; Figure 5 is the same view as Figure 4 but with the device in the inoperative position; Figure 6 is a plan view of the device of Figure 3 with a ladder being placed in position; Figure 7 is a plan view of the device of Figure 4 with the ladder fully in I..' position; Figure 8 is a side view of the device of either embodiment in use with SI...

* * scaffolding; Figure 9 is a side view of another embodiment of the device; and

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: Figure 10 is a side view of the device of the embodiment of Figure 9 in use with scaffolding; The device 10 in Figure 1 is seen from above with the upper surface 12 in place.

Accordingly, the internal parts are shown in broken lines. The device is generally box shape having a front wall 14, a back wall 16 and two side walls 18. The upper surface 12 does not extend across the entire area defined by the front, back and side walls. Rather, there are two slots 17, open in the same plane as the front wall 14, one at either end of the device 10 defined by the side walls 18, the back wall 16 and the extent of the upper surface 12. These slots will be explained in more detail below.

At the rear of the device attached to the back wall 16 are two clamps 20. These clamps are capable of receiving a scaffolding bar 22 as shown by the broken line such that the device 10 may be clamped to the scaffold bar in a particular orientation (typically horizontal).

Each slot 17 is sized to accommodate the stile of a ladder 50 such that in use the device fits between the two stiles of a ladder (so that each stile is either side of the : .. device in the horizontal plane) and also so that the device fits between adjacent *s..

rungs 52 of the ladder (so that one adjacent rung is substantially above the device and the other adjacent rung is substantially below the device). At the open end of each slot, which lies in the same plane as the front wall 14, a moveable member 30 is located. These movable members are in the form of rods 30 which are S. S *. .: connected to shafts 36 (which act as pivots) at one end. The other end of each rod moves into, and out of, a respective slot in each side wall 18 as the rod turns about the pivot formed by the respective shaft 36. These slots cannot be seen in Figure 1 due to the angle of view, however, an equivalent slot is shown in Figure 9 referenced 255.

A lug 31, or tab, is provided on each shaft 36 substantially radially opposite the rod 30. Although in Figure 1 the lugs 31 are positioned axially adjacent each rod they may be located axially spaced from each rod 30. The purpose of the lugs 31 will be described in more detail below Each shaft 36 extends through holes in the front 14 and back walls 16 to support them so that they lie substantially in the same plane as the upper surface 12. Each rod 30 rotates about the longitudinal axis of each shaft 36, as shown by reference "A" in Figure 1. A cord, or chain, 40 is connected between each lug 31. The device 10 will be further explained below with regard to Figure 2 which is a cross-sectional side view along line fi as shown inFigurel.

Each rod 30 is shown in solid lines and in broken lines. The rods shown in solid :.. lines are in the operative position. In other words the rods 30 are in such a position that they obstruct the open end of the slots 17. To orientate a ladder with the device 10 therefore, the rods 30 need to be moved to the inoperative positions such that they do not obstruct the slots 17 (best seen in Figure 1). This is effected by *. S * -pulling the cord, or chain, 40 so that the two rods pivot about the shafts 36. The

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two rods pivot until they reach the inoperative positions shown in broken lines. At this point it will be seen that the two slots 17 are unobstructed such that a ladder 50 may be presented to and placed inside each slot 17. The rods are then moved back to the operative position (shown in solid lines). This is effected merely by releasing the cord or chain 40 such that the weight of the rods move under the force of gravity. Other means for returning the rods to their active positions could also be utilised such as biasing means in the form of springs.

Also shown in Figure 2 are two locking tabs with holes 39. These tabs are connected to each rod 30 axially from the shaft 36 end of each rod 30. The holes align with corresponding holes in the front wall 14 such that a bolt or padlock etc. may be placed through them to lock the rods 30 in either the inoperative or operative positions.

The device 110 in Figure 3 is another embodiment which comprises a box shape housing having an upper surfhce 12 (refer to Figure 4), a bottom surface or base plate 13, a front wall 14, a back wall 16 and two sidewalls 118. The upper surface is shown removed to improve the clarity of the drawing. However, this surface could have a friction coating or be formed with a pattern of raised shapes (for instance in the well known Durbar (RTM) format) to improve its grip. *... * a

The device may be made from sheet steel for improved life expectancy. S..., * .

Attached to the rear wall 16 of the device 110 are two clamps 20. These clamps are capable of receiving a scaffolding bar 22 as shown by the broken line such that the device 110 may be clamped to the scaffold bar in a particular orientation.

Within the device 110 are two movable members 30, one at each end of the device, which in the operative positions project outwardly through the side walls 118.

Each member 30 has an arm 34 and a counterweight 38 which extend at right angles to each other. The member is pivoted about pivot point 136 with the arm 34 and the counterweight 38 on opposite sides thereof. The member may rotate about the axis, as shown by reference "B" in the figure, of the pivot point 136. At the free end of arm 34 is a wedge shape member 32. These members 32 are wedge shape in that their thickness (as measured in the direction from the front waIl 14 to the back waIl 16 of the device) diminishes in a direction from the centre of the housing towards the side walls 118, in a plane parallel to the base plate 13. The slope of the wedge shape members 32 is on the front face, the rear face being parallel with the rear wall 16 of the device 110. The counterweight 38 located on the opposite side of the pivot point 136 from the arm 34 acts as a counterbalance weight, as will be explained in more detail below, and remains inside the housing of the device 110. * ** * * . ***

Figure 4 is a side view of device 110 shown in Figure 3 as seen along arrow LV.

The device 110 is shown in position with and against a scaffold bar 22. A ladder I.....

* 15 50 is shown with one stile on each side of the device adjacent to side walls 118.

The clamps 20 are not shown for the sake of clarity. Further, the device 110 is * shown in a cut-away format such that the parts may be more clearly seen within the interior of the device. The members 30 are pivoted about pivot point 136 such that the wedge shape members 32 may move downwards, with respect to the drawing. This downward movement of the wedge shape members 32, located at the outer ends of arms 34, is accompanied by a corresponding upward movement of the counterweights 38. One way of moving the assemblies 30 in this manner is by pulling a cord or chain 40 away from the housing of the device. This cord is attached to each arm 34 and is guided by various pullies 42 through a hole 46 in the base plate 13.

In the arms 34, holes 39 are provided. These holes align with corresponding holes (not shown) in the housing of the device 110 (for instance in the front waIl 14 or back wall 16) when in the two extreme positions (fully extended and fully retracted). In this manner, a padlock or bolt may be positioned through the corresponding holes such that the arms are secured in place and with respect to the housing. In this manner, and especially if a padlock is used, the assemblies could be locked in the position such that the wedge shape members 32 are fully extended so that a ladder could be secured. In this way only the key holder may remove the : ** ladder. This has the advantage that the device may be used as a security device to ** prevent theft or other unauthorised removal.

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By pulling on the cord 40, it may be seen from Figure 5 that the two members 30 have rotated around pivot points 136 such that the two wedge shape members 32 at *. ,. the end of each arm 34 are fully retracted with respect to the housing of the device 110. By releasing the cord 40, the rigid movable assemblies will return to the extended positions. This may be achieved by counterweights 38 or by resilient means (such as a spring) not shown. Instead of a cord 40, a chain or other more bardwearing structure could be employed.

Another way of moving the assemblies 30 is shown in Figure 6 which is another plan view of the device 110. In this figure a ladder 50 is shown being placed against the device 110. It is seen that the stiles 50 are pushed against the wedge shape members 32 at the end of arms 34 towards the back wall 16 of the device 110. This pressure causes the wedge shape members 32 to slide past the stiles of the ladder 50 and rotate into the housing about pivot points 136, the rotation indicated by reference "B" in the figure. By retracting into the device, the ladder may be positioned so that the stiles will pass behind the wedge shape members 32.

This position is shown in Figure 7 where it may be seen that with the ladder stiles in the fully located position the wedge shape members 32 have returned to their fully extended position, with respect to device 110. This is because the stiles have moved beyond the point where they are providing lateral pressure on the wedge shape members 32. As discussed above, this return movement is caused by : .: counterweights 38 or resilient means (not shown). In this manner, the stiles of the a...

S..... ladder 50 are trapped between the scaffold bar 22 and the rear surface of the wedge shape members 32. Since the wedge shape members 32 only have a sloping **5*I * . 15 surface on the front side they effectively allow the ladder to pass only one-way * : * * with respect to them. Further, since the housing of the device 110 lies between two a. . * . rungs 52 of the ladder it inhibits movement of the ladder laterally (i.e. sideways) and also up and down.

In Figure 8, the device is shown in use in two slightly different positions with regards to scaffolding 60. The scaffolding 60 is placed against a structure such as a house 70. The scaffolding 60 comprises uprights 62 and cross members 63 to provide rigidity. Further, cross members 64 (which may lie perpendicularly to the cross members 63) are present. The device 110 may be attached to one of these cross members 64. Alternatively, or additionally, an additional cross member 66 may be attached to the scaffolding 60 and the device 110 attached to that. As may be seen, the device 110 and ladder 50 may be positioned so that they are either outside of the scaffolding 60 or such that they are substantially within the frame created by the scaffolding 60. In this manner, the ladder is held at its upper end so that it may not move sideways, backwards or forwards. Further, the ladder is substantially held so that it will not move upwards or downwards. Although the device is referenced as 110 it could equally be the device 10 of the first described embodiment.

A further embodiment of the invention is shown from the side in Figure 9. This : .. comprises a device 210 one side wall 218 of which can be seen to have an S...

approximately right-angled triangular shape. At the top, as viewed in the Figure, *: the device has an upper surface 212. A back wall 216 is shown to the left, and a iS front wall 214 to the right, as viewed in Figure 9. The device 210 operates in substantially the same way as described with regard to the first embodiment shown S. .: in Figures 1 and 2. In other words, movable members, or rods, 230 are provided within the device 210 for retaining ladder stiles in slots. Within the side wall 218 of this embodiment a slot 255 is provided. Another slot 255 is provided in the other side waIl 218, not shown. These slots 255 receive the free end of each rod 230 when the rods are moved to their operative positions.

This embodiment could also operate in substantially the same way as described with regard to the second embodiment shown in Figures 3 107 In this embodiment the back wall is substantially taller than the front wall 214.

Clamps 220 for attaching the device 210 to scaffolding are secured, for example by welding, on the back wall 216. Other means of attaching the device 210 to other structures are of course possible. However, in this embodiment, the clamps 220 are positioned towards the lower end of the back wall 216, as shown in Figure 9.

This position is selected so that when the device 220 is attached to a horizontal scaffold tube by means of the clamps 220 there is a predetermined gap between the top of the scaffold tube and the upper surface 212. This gap is selected to be approximately the same as the thickness of a standard deck board so that when such a deck board is placed on, and supported by, the scaffolding tube to which the ::::. device 210 is attached, its upper surface is substantially at the same horizontal S...

level as the upper surface 212 of the device 210. This provides a substantially continuous level surface for personnel so that when a user climbs the ladder he * : 15 may step off the upper surface 212 of the device 210 onto a deck board, or walkway, which is at the same level. This aspect improves safety as it removes a *:. triphazard.

A better understanding of this concept may be realised from Figure 10 where the deck board is referenced 276. The scaffolding structure 260 has uprights 262 and horizontal cross-bracing 263, 264, to one of which the device 210 is attached by means of the clamps 220. A ladder 250 is shown in position and locked into place by the device 210. The upper surface 212 of the device 210 is substantially level with the upper surface of the deck board 276.

Claims

CLAIMS

1. A ladder safety device for securing a ladder to a structure against which the ladder is placed having means for securing the device to the structure and means for restraining the movement of the ladder at least in one direction relative to the structure, said means including at least one member which is displaceable between an operative position in which it restrains the movement of the ladder and an inoperative position.

2. A ladder safety device according to claim 1, wherein the member is substantially linearly displaceable between its operative and inoperative : *. positions. U... * * *.*

* * 3. A ladder safety device according to claim 2, wherein in the operative * 15 position the at least one member is extended with respect to the device and *** in the inoperative position the at least one member is retracted with respect *. . * * * * to the device.

4. A ladder safety device according to claim 1, wherein the rigid movable member is displaced from its inoperative to its operative position by rotary motion.

5. A ladder safety device according to claim 4, wherein in the operative position the at least one member protrudes from the device and in the inoperative position the at least one member lies substantially within the device.

6. A ladder safety device according to any preceding claim, adapted to fit between the stiles of a ladder such that in the operative position the at least one member lies transversely across the at least one stile such that the at least one stile is trapped between the at least one member and the structure against which the ladder is placed.

7. A ladder safety device according to any preceding claim, wherein the at least one member is adapted to move from its operative position to its : *. inoperative position by the pressure of the ladder stile against it. "I * S *5**

8. A ladder safety device according to any preceding claim, wherein the at S..... . * 15 least one member is rigid. S. S * S S * S

9. A ladder safety device according to any preceding claim, wherein the member is biased towards its operative position.

10. A ladder safety device according to any preceding claim, wherein the device further includes means for attaching it to scaffolding.

11. A ladder safety device according to claim 10, wherein the means for attaching the device to scaffolding are so positioned that, in use, an upper surface of the device is positioned at substantially the same horizontal level as the upper surface of an adjacent deck board supported, at least in part, by the section of scaffolding to which the device is attached.

12. A ladder safety device according to any preceding claim, including means for locking the member in either or both of its inoperative and operative positions.

13. A method of retaining a ladder in a working position placed against a fixed structure by restraining the movement of the ladder by at least one member.

14. A ladder safety device having means for restraining the ladder against displacement in at least one direction, in which engagement of the * restraining means is effected automatically upon placement of the ladder S..,..

* . 15 there against. 5* 5 U. * * . *. U

U 15. A method of securing a ladder in a working position comprising the steps of placing the ladder in position against a structure in engagement with a housing which restrains lateral movement of the ladder, positioning at least one restraining member over one and preferably both stiles in a position such as to restrain movement of the ladder away from the said structure, and repositioning the foot of the ladder to take up any clearance between the ladder stile or stiles and the restraining member.

16. A ladder safety device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

17. A method of securing a ladder in a working position substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings. * ** ** S S... S.. * S *5I

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