GB2388868A

GB2388868A - Safety device for ladders

Info

Publication number: GB2388868A
Application number: GB0211652A
Authority: GB
Inventors: Colin David Shipp
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-21
Filing date: 2002-05-21
Publication date: 2003-11-26
Also published as: GB0211652D0

Abstract

A safety device for ladders 1 comprises two spirit levels 3, 4 which may be linked by a frangible connection (7, figure 3). The first spirit level 3 is arranged so as to indicate when the ladder is positioned at a safe angle for usage and the second spirit level 4 is arranged to indicate when the device 1 is positioned correctly in relation to the ladder. The device 1 has fixing means for attaching it to a ladder. The device may also provide a visual or audible indication when it is in a particular orientation relative to the horizontal. Alternative level indicators may be used such as a plumb-line, a sphere in a graduated tube or a pivoted see-saw. A method of attaching a safety device to a ladder is also disclosed.

Description

(. Safety Device for Ladders The present invention relates to devices

which facilitate the safe operation of ladders, in particular devices which ensure that a ladder is operated at a safe angle.

A particular hazard in the operation of ladders is the use of a ladder which is positioned at an inappropriate angle against a vertical surface. A ladder which is angled too steeply is liable topple backwards whilst a ladder which is angled too shallowly may slide backwards from its base. In either case, there is a risk of injury to the user.

5 Various devices have been employed to address this problem. US2,845,719 describes a ladder which has a device attached to a side-rail which comprises an air bubble tube such that the air bubble is centered when the device is at a safe angle. The device has an annular to flange with various marked positions. The air bubble tube can be rotated between these positions so that the safe angle can be altered depending the frictional properties of surface on which the ladder is placed.

25 US3118234 describes a plumb-line arrangement contained within a housing which is attachable to the side rail of a ladder to indicate when ladder is safely angled.

US4,554,994 describes a ladder which has an air bubble 30 tube fixed to a side rail to indicate when the ladder is at a safe angle relative to the vertical and a second indicator at the foot of the ladder which indicates when the ladder is safely angled relative to a sloping support surface.

Indicator devices such as described above must be attached or built into to the ladder with some precision to ensure that they are in the correct orientation relative to the ladder to indicate the safe angle of 5 operation of the ladder. This level of precision may present some difficulties for the user, particularly in a domestic situation.

The present invention relates to a ladder safety device lo which can be placed on a ladder in the correct orientation quickly and easily.

A first aspect of the present invention provides a safety device for a ladder comprising; 15 a first level indicator positionable in a first angular arrangement relative to the ladder such that the first level indicator indicates when the ladder is at a safe angle for operation, wherein; 20 the device further comprises a second level indicator which indicates when the first level indicator is positioned in said first angular arrangement.

The second level indicator indicates when the device is 25 at a first orientation relative to the horizontal (for example, horizontal or vertical). A device in the first orientation may be fixed to a ladder which is at a second orientation relative to the horizontal (conveniently horizontal or vertical). When the device is so fixed, the 30 first level indicator is positioned in said first angular arrangement relative to the ladder.

The second level indicator thus allows the first level indicator to be positioned so it indicates the safe operational angle of the ladder.

5 The device may be fixed to a ladder, in particular to the side rail of a ladder, at any convenient point. The device can thus be positioned in accordance with the physique or preference of a particular user. For example, a tall person may prefer to position the device higher up 10 the ladder than a shorter person.

In will be understood that the designation of an orientation of the device as horizontal, vertical or otherwise will depend on the shape and configuration of 15 the device. The first orientation as determined by the second level indicator may be any orientation which positions the first level indicator in a first angular arrangement relative to the ladder, as described herein.

to Preferably the second orientation of the ladder is selected so as to be easy to determine, for example vertical or horizontal.

In some embodiments, the device may be fixed to a ladder 25 which is in the same orientation relative to the horizontal (conveniently, for example, both device and ladder may be parallel to the horizontal) or the device and ladder may be in different orientations (e.g. the device may be vertical, and the ladder horizontal or vice 30 versa).

Orientation or angular arrangement of a ladder as described herein refers to the angle of the principal

( axis of the ladder relative to the vertical or the horizontal. The first and second level indicators may, for example, 5 be arranged on the device such that when the second level indicator indicates that the device is in a first orientation relative to the horizontal (for example parallel to the horizontal), the first level indicator is itself orientated so as to indicate when the device is at lo an angle which is safe for the operation of a ladder.

The device may thus be fixed to a suitably orientated ladder using the second level indicator and the ladder then operated using the first level indicator to determine the safe angle of operation.

The safe angle of operation may be determined relative to the horizontal. Conventional safety standards indicate that the base of a ladder is located a distance from so the vertical which is equal to one fourth the working height of the ladder. This provides for a safe angle of operation of about 76 relative to the horizontal i.e. 14 relative to the vertical. Factors such as the slope and frictional resistance of the supporting base will also Is influence the safe angle of operation of a ladder.

A level indicator provides a visual or audible indication of angular orientation relative to the horizontal (or vertical) plane. In particular, a level indicator may JO provide an indication when it is in a particular orientation relative to the horizontal (or level) plane, in particular when it is either perpendicular to or parallel to the horizontal plane.

( Suitable level indicators for providing indication when perpendicular to the horizontal plane include a plumb-

line. This is a free hanging member (for example, a 5 weighted line) which aligns under gravity with the vertical plane.

Suitable level indicators for providing indication when parallel to the horizontal plane include spirit levels. A lo spirit level is a sealed chamber (for example a slightly curved transparent tube) partially filled with liquid which is set so that an air bubble within the liquid is positioned between two graduated marks when the spirit level is horizontal. Other suitable level indicators for 15 providing indication when parallel to the horizontal plane may comprise a sphere (for example, a steel ball or bearing) in a graduated tube or a pivoted see-saw (i.e. an elongate member pivotally connected at a central point to the ladder).

Other suitable level indicators are well known to those of skill in the art and may be used in accordance with the present invention.

25 In some embodiments, the first and second level indicators may be arranged so as to provide indication of the angle of the device at a first position and at a second position, the angular difference between the first and second positions being equal to the safe angle of so operation (i.e. about 76 ).

The first and second level indicators may be of the same type (for example, two plumb lines or two spirit levels),

! or may be of different types (for example a plumb line and a spirit level). In preferred embodiments, one or, more preferably, both of said first and second level indicators are spirit levels.

In embodiments in which the first and second level indicators are spirit levels, the first spirit level may be orientated with respect to the second spirit level at a angle which is 180 minus the safe angle of operation.

lo A suitable angle may be between 100 and 130 , more preferably between 110 and 120 and most preferably about 114 . This arrangement provides for the second level indicator to indicate the device is correctly aligned with a horizontal ladder and the first level indicator to indicate a safe angle for operation of a ladder as described herein.

Alternatively, the first spirit level may be orientated with respect to the second spirit level at an angle which so is 90 minus the safe angle of operation. This arrangement provides for the second level indicator to indicate that the device is correctly aligned with a vertical ladder and the first level indicator to indicate a safe angle for operation of a ladder as described herein.

A safety device may comprise fixings for attachment to a ladder, most preferably to the side rail of a ladder. A suitable fixing prevents the rotational movement of the device relative to the ladder once attached. A variety of So suitable fixings are known in the art and include plastics material or metal cable ties, screws, bolts, adhesives or adhesive patches or tapes, hook and loop

( fastenings (e.g. Velcrotm), clips, dowels (wood, metal, plastics material) nails or staples.

Fixings may be releasable or non-releasable. For example, s a device may be fixed permanently to a ladder or may be removed after use, for example to prevent theft or damage during transport or storage. Preferably, a releasable fixing comprises a first component which remains permanently fixed to the ladder and a second component lo which is reversibly attachable to the first component, the device being attached to the second component. This allows the device to be removed and replaced on the ladder without the need for repositioning. Suitable first and second components include the hook and loop portions, 15 respectively, of a hook and loop fastening, a magnet and a body magnetically attracted thereto or a bracket and a member which engages therein.

Said first and second level indicators may be mounted on 20 a body. A suitable body may be of essentially planar rectangular shape and made of metal, wood or a plastics material. A body of the device may comprise holes to facilitate attachment as described above, for example using cable ties, screws or bolts.

The first level indicator may be graduated to provide indication of the actual angle of the ladder relative to the safe angle of operation, for example to indicate when the ladder is at an unsafe angle. The allows the so convenient adjustment of the angle of the ladder during operation.

( The first and second level indicators may be linked by a frangible connection. For example, the body may comprise a line of weakness which separates the first and second level indicators. The second level indicator may thus be 5 removed once the device has been attached to the ladder in the correct orientation.

In some embodiments, the safety device may comprise a third level indicator which is perpendicular to the first lo and second level indicators (i.e. perpendicular to the plane which is defined by the first and second level indicators). The third level indicator shows the orientation of the ladder relative to the plane perpendicular to the wall or surface against which the IS ladder is leaning (i.e. whether one leg or side rail of the ladder is higher than the other such that the rungs are not horizontal). The user can thus determine whether the ladder is straight relative to the wall or other surface. Further aspects of the present invention relate to methods for the operation of a safety device as described herein. For example, a method for fixing a safety device comprising first and second level indicators to a ladder 25 may comprise, positioning the ladder in a second orientation relative to the horizontal, positioning the said device in a first orientation indicated by a second level indicator of said device, so attaching said orientated device to said orientated ladder, such that the first level indicator of said device is orientated relative to the ladder to indicate when the ladder is at a safe angle for operation.

( As described above, the first and second orientations may he horizontal.

5 Aspects of the present invention will now be illustrated with reference to the accompanying figures described already above and experimental exemplification, by way of example and not limitation. Further aspects and embodiments will be apparent to those of ordinary skill lo in the art.

All documents mentioned in this specification are hereby

incorporated herein by reference.

15 Figure 1 shows a safety device (1) according to one embodiment of the present invention. Spirit levels are shown shaded with air bubble in white.

Figure 2 shows a safety device (1) with a graduated first so level indicator according to another embodiment of the present invention.

Figure 3 shows a safety device (1) with a frangible connection between the first and second level indicators 25 according to another embodiment of the present invention.

A substantially planar body (2) comprised of a plastics material has four sides A, B. C and D. Sides A and C are essentially parallel and are cm apart. Side D is at 30 right angles to sides A and C. Side B is angled at about 114 C relative to side A and at 76 relative to side C, such that side C is cm longer than side A. Lengths and are arranged such that ratio alp is 4.

( A first spirit level (3) and a second spirit level (4) are mounted on the body adjacent and parallel to sides A and B of the body (2) such that the angle between the s first and second spirit levels (3,4) is 114 .

The body (2) also has fixing holes (5) which allow the device (1) to be attached to the side wall of a ladder (not shown) by means of ties or screws.

In use, the device (4) is orientated horizontally using the second spirit level (4), which provides visual indication when the device is horizontal. A ladder to which the device is to be attached is also orientated 15 horizontally, conveniently by resting it flat on the ground. The horizontally aligned device (1) is then attached, by means of the fixings (5), to the side wall of the horizontal ladder. Sides A and C of the body (2) are thus parallel to the side walls of the ladder and JO side D is perpendicular thereto. Side B. upon which the first spirit level (3) is mounted, describes an angle of 76 relative to the side walls of the ladder.

When the ladder is used, an end is raised to contact a 25 substantially vertical surface. The first spirit level (3) is essentially horizontal and the air bubble therein centered when the ladder is at an angle of about 76 relative to the ground. This is a safe angle for operation and minimises the risk of the top of the ladder So toppling backwards or the bottom sliding backwards. The first spirit level thus provides a visual indication to the user of when the ladder is positioned safely for use.

( Figure 2 shows a safety device according to another embodiment. The first spirit level (3) comprises graduations (6) which indicate when the angle of the ladder is not safe for operation or requires further s adjustment. For example, when the air bubble of the spirit level (3) is in a proximal zone, the ladder may need fine adjustment, but when the air bubble is in a distal zone, the ladder is unsafe for use.

lo Figure 3 shows a safety device according to another embodiment. The body (2) of the device comprises a line of weakness (7) in the form of a series of perforations which separates the first and second spirit levels (3, 4). Once the device is attached to a ladder using fixings 15 (5), the body (2) is snapped or broken manually along the line of weakness (7) to remove the second spirit level, which is largely redundant once the device has been permanently attached to a ladder. This leaves the first spirit level fixed in place to determine safe operation to of the ladder.

Claims

( _laims: 1 A safety device for a ladder comprising; 5 a first level

indicator positionable in a first angular arrangement relative to the ladder such that the first level indicator indicates when the ladder is at a safe angle for operation, wherein; the device further comprises a second level lo indicator which indicates when the first level indicator is positioned in said first angular arrangement.
2. A safety device according to claim 1, wherein; the second level indicator indicates when the device 15 is at a first orientation relative to the horizontal which is suitable for fixing the device to a ladder at a second orientation relative to the horizontal, the first indicator being positioned in said first angular arrangement relative to the ladder when the 20 device is so fixed.
3. A safety device according to claim 2 wherein said both first and second orientations are parallel to the horizontal.
4. A safety device according to any one of the preceding claims wherein one or both of said first and second level indicators are spirit levels lo
5 A safety device according to claim 4 wherein both of said first and second indicators are spirit levels.

(
6 A safety device according to claim 5 wherein said first spirit level is orientated with respect to the second spirit level at a angle which is 180 minus the safe angle of operation.

s
7. A safety device according to claim 6 wherein said first spirit level is orientated with respect to the second spirit level at an angle between 100 and 130 lo
8. A safety device according to any one of the preceding claims wherein said safe angle of operation is about 76 relative to the ground.
9. A safety device according to claim 8 wherein said first spirit level is orientated with respect to the second spirit level at about 114 C.
10. A safety device according to any one of the preceding claims comprising fixings for attachment to a 2 o ladder.
11. A safety device according to any one of the preceding claims wherein said first and second level indicators are mounted on a body
12. A safety device according to any one of the preceding claims wherein said first level indicator is graduated to indicate the angle of the ladder relative to the safe angle of operation.
13. A safety device according to any one of the preceding claims wherein the first and second level indicators are linked by a frangible connection.
14. A safety device for a ladder substantially as described herein and shown in the accompanying figures.

5
15. A method of attaching a safety device to a ladder comprising, positioning the ladder in a first orientation, positioning the said device in a second orientation by means of a second level indicator, lo attaching said orientated device to said orientated ladder, such that the first level indicator is orientated relative to the ladder so as to indicate when the ladder is at a safe angle for operation.