GB2068547A - Inclinometers - Google Patents

Abstract

An inclinometer for indicating whether a ladder is safely positioned comprises a pivotally mounted 16 loaded disk 18 having an aperture 22 which moves over coloured markings 24-28 on the ladder or a back-plate attached to the ladder, in another embodiment, the disk may comprise pointers movable over coloured markings. Alternatively the inclinometer may comprise a ball rolling in and visible through windows in a curved tube, or a liquid where meniscus is compared against a scale. <IMAGE>

Description

SPECIFICATION Inclinometer device The invention relates to an inclinometer useful particularly but not exclusively as a safety indicator device for a ladder, and also to a ladder incorporating such a device.

It is a general rule for safe use of ladders, that the ladder shall make an angle of substantially 750 with the supporting surface, assumed to be horizontal, and consequently an angle of substantially 1 50 with a surface, assumed to be vertical, on which its upper end rests. It is not always easy to assess this angle with sufficient accuracy for safety to be ensured, particularly where work is being done on overhanging or recessed parts of a building.

The invention is accordingly concerned with the provision of an inclinometer capable of use as a safety indicator device, and a ladder incorporating such a device, whereby a safe angle of the ladder is reliably and conveniently indicated. The inclinometer, suitably calibrated as with a scale of degrees, can be used instead for example for measurement of the inclination of a floor or other part of a structure.

The invention accordingly provides an inclinometer device comprising a gravitationallybiassed member movable with respect to means providing a predetermined marking to indicate the inclination of the device. The marking can comprise a scale or marking specifically to indicate whether or not the angle of inclination of a ladder to which the device is secured is within a safe range.

The gravitationally-biassed movable member can be for example a weighted disc or pointer mounted to pivot on a transverse axis of the ladder, and cooperable with a degree scale marked on the ladder or on a cooperating member which can be fixed to the ladder, so as to secure the device in place. Alternatively, the gravitationally-biassed member can comprise a body of liquid having a meniscus movable within a marked or calibrated transparent container, or a ball or roller movable in a curved, preferably arcuate, track which may be constituted by a closed-end tube, the track being marked to indicate the positions of the ball or roller which corresponds to an inclination which may be read from the markings, or to a safe and/or a dangerous inclination of the ladder.

The device of the invention is preferably located on a ladder at an inner side of one of the stiles, so as to be protected from damage and may be advantageously recessed into the stile.

Conveniently, the device is located at d position from the lower end of the ladder corresponding to normal eye level.

The device is preferably arranged to operate correctly regardless of which side of the ladder is laid uppermost. The device can be so arranged that a correct indication will be given regardless of which way up it is set up on a ladder.

The device is further described below, by way of example, with reference to the accompanying drawings in which: Figure 1 is a front view of a first inclinometer device embodying the invention; and Figures 2, 3, 4 and 5 are like views of second, third, fourth and fifth such embodiments respectively.

The inclinometer device 1 of Figure 1 comprises a backing plate 12 of generally square configuration except for upper and lower lugs 14, each apertured to receive a fastener by means of which the device is secured to a ladder stile 1 5 for use as a ladder safety indicator device. A pivot pin 16 extends outwardly from the centre of the backing plate 12 and a weighted disc 18 is freely journalled on this pin at its centre. The disc 18 is weighted by the securement to the outer side thereof, of a mass 20, of lead or the like. The diameter 21 of the disc 18 which passes through the gravitational centre of the mass 20 is symmetrically straddled by a window or aperture 22 in the disc, located on the side of the pivot pin 1 6 remote from the mass.

Along an arcuate track centred on the axis of the pivot pin 1 6 and registering with the aperture 22 of the disc 1 8, the free surface of the backing plate 12 is provided with a multi-coloured strip, comprising an inner portion 24, and two outer portions 26, all coloured red, the inner and outer portions being separated by two intermediate portions 28 coloured green. The median line of the inner portion 24 has along the centre line 25 of the backing plate 12, which extends along the centre line of the stile 1 5 in use. The shape and arcuate extent of the green portions 28 preferably corresponds to that of the aperture 22. The green portions 28 are positioned with their median lines angularly spaced by 300 on either side of the centre line 25.

It will be evident that the diameter 21 of the disc 1 8 will remain always vertical, by rotation of the disc about the pivot pin 1 6. When the ladder is at a correct inclination, that is, at 750 to the horizontal, the aperture 22 will register precisely with one or other of the green portions 28. When it is at a greater angle to the horizontal, at least part of the central red portion 24 will appear in the aperture 22, and if inclined at a smaller angle than 750, at least a part of one or other of the extreme red portions 26 will be seen in the aperture.

The aperture 22 thus aiways provides a clear visual indication as to whether or not the inclination of the ladder is one that can be employed with safety. Any appearance of red within the aperture indicates that the position of the ladder should be adjusted for maximum security until only a green portion can be seen.

The backing plate 12 is arranged to be symmetrical about a line through the pin 16 and perpendicular to the line 25, so that it can be mounted on the ladder either way up. Thus the red.

and green markings 24, 26 and 28 are repeated at diametrically opposed positions, as shown in the lower part of Figure 1.

The green marking portions 28 need not correspond to the aperture 22 in arcuate extent, but may be greater, to indicate a range of safety on either side of the strict 750 inclination. The outer red portions 26 can extend away from the green portions 28 to any extent considered appropriate.

The device 1 is preferably mounted on the inner side of one stile of the ladder so as to be protected to some extent from damage, at a position from the foot corresponding to normal eye level, so as to be easily read by the user. Where incorporated in a ladder at the manufacturing stage, the device can be at least partially recessed into the stile. A transparent cover can be provided to enclose the disc 1 8 if desired.

It will be evident that the shape and markings of the disc 18 and the backing plate 12 can be widely varied. For example, the aperture 22 could be replaced by a notch or recess at the edge of the disc 18, or the disc could be replaced by a triangular member with a pointer at the apex opposite a weighted base. The markings could additionally indicate the ladder inclination in degrees, or such indication could replace the colour coded markings when the device would be capable of wider application. The backing plate 12 can be constituted by the stile of the ladder itself on which the markings are stencilled or otherwise applied. If constituted as a separate item, the backing plate need be no larger than is necessary to provide the markings.It can then be arranged to be fixed in place, and the disc 1 8 assembled with it after fixing, so that the disc covers the fastenings. It is however advantageous, when the device is supplied as a separate item, to provide the backing plate with parallel sides, to facilitate correct alignment of the device with the ladder stile.

In the second embodiment of the invention, illustrated in Figure 2, the gravitationally biassed member is constituted by a ball 30, which is free to roll along an arcuate track. The track is defined by an arcuate tube 32, fixed to an arcuate backing plate 34. The plate 34 extends at either end beyond the tube 32 to provide apertured portions for fixing the device to the stile of a ladder. The device is secured so as to be intersected by the main axis 35 of the stile, so that the ball 30 occupies a position on this axis, as shown on Figure 2, when the ladder is accurately vertical.

When tilted from the vertical, the ball 30 will roll towards one or other end of the tube 32, and will take up a rest position spaced from its neutral position by an extent dependent on the inclination of the ladder. To indicate a safe inclination, the tube 32 is provided with a pair of windows 36 positioned so that the ball 30 will register with one of them only when the ladder is inclined at 750 to the horizontal.

The device of Figure 2 can of course be modified in various ways. For example, the tube 32 can be transparent throughout its length, the safe positions of the ladder being indicated by markings at appropriate positions along its length.

The tube may be calibrated, so that the ball 30 indicates the actual angle of inclination, and if it is desired to make the device symmetrical, the tube can be continued to form a complete circle, provided with four of the windows 36, or functionally equivalent markings, of which only one of the lower two will be operative at any given time.

In place of a rolling ball, a roller or other shaped mass capable of movement along any suitable kind of arcuate track can be employed in modifications of the Figure 2 embodiment.

The third inclinometer embodying the invention, shown in Figure 3, comprises a circular backing plate 42 and a generally semicircular weight 48 which may be for example a metal plate. The weight 42 is rotatably connected to the plate at the common centre by a pivot pin 46. An indicator bar 44 extends along the diametral edge of the weight 48 to provide outwardly projecting pointers 50 at its ends which overlie a circular scale or track 52 on the plate 42. For use on the stile of a ladder having a main axis 45, the track 52 can have four portions 54 marked green the remainder being red. The latter is at a safe inclination only when the pointers 50 register with a diametrically opposed pair of the portions 54.

The track 52 can instead or as well carry a scale of degrees.

The fourth inclinometer of the invention, shown in Figure 4, also comprises a generally semicircular weight 61 rotatably suspended, at a pivot position 66 midway along the diametral edge of the weight, on a backing plate 62 or directly on the stile of a ladder having a main axis 65. A central cut-out or recess 67 extends upwardly from the curved lower edge of the weight. In the safe angular position of the ladder, the recess 67 registers with one or other of a pair of messages "SAFE" marked on the backing plate 62, the messages being partially or completely obscured by the weight in other positions. The message projects beyond the periphery of the weight as an indication of their existence in such other positions.

The fifth inclinometer of the invention shown in Figure 5 has as its gravitationaily-biassed movable member a body of liquid 72 contained in a flat circular container 74 having a back plate carrying markings and a transparent front plate. The liquid may be of any kind but is preferably rather dense and may be transparent or opaque. The container 74 is half full with the liquid 72 so its meniscus 78 extends along a diameter of the container if its front and back plates are vertical. The back plate of the container can be marked with a scale, but if the inclinometer is for use on the stile of a ladder having a main axis 75, two diameters 76 can be marked as indicated, so that the ladder is at a safe inclination when the liquid meniscus is aligned with one of them.

It will be understood that certain features of some of the embodiments can be applied to others, for example, the annular marking track of Figure 3 can be carried by the container of Figure 4 or the backing plate of Figure 5 in the place of or as well as the markings shown.

The markings can be arranged to indicate only a single safe position of the ladder, where it is intended that the inclinometer shall have only a single appropriate position of use on the ladder.

Claims (14)

1. An inclinometer in combination with a ladder, the inclinometer comprising a gravitationally-biassed element movable in response to movement of the ladder between safe and unsafe attitudes of use thereof, and marking means co-operable with the element to provide a visual indication of the relationship of the attitude of the member to the safe attitude.

2. An inclinometer as claimed in c!aim 1 wherein the element is mounted directly on the ladder which carries the marking means.

3. An inclinometer as claimed in claim 1 wherein the element is mounted as a backing plate carrying the marking means, the backing plate being secured to the ladder.

4. An inclinometer as claimed in claim 3 wherein the marking means permit the backing plate to be secured in place in either of two positions angularly spaced by 1 800.

5. An inclinometer as claimed in any preceding claim wherein the marking means comprise words and/or coloured areas and/or a scale of degrees.

6. An inclinometer as claimed in any preceding claim wherein the element includes pointer means registering with a marking of the marking means indicating the safe and/or unsafe attitude of the ladder.

7. An inclinometer as claimed in any preceding claim wherein the element is apertured or recessed to reveal a marking of the marking means indicating the safe and/or unsafe attitude of the ladder.

8. An inclinometer as claimed in any preceding claim wherein the element comprises a generally semicircular plate pivoted substantially at the mid point of its diametral edge.

9. An inclinometer as claimed in claim 8 as dependent on claim 6 wherein the element comprises pointer means extending along the diametral edge.

10. An inclinometer as claimed in any one of claims 1 to 7 wherein the element comprises a generally circular plate weighted at its periphery and rotatable about its axis.

11. An inclinometer as claimed in any one of claims 1 to 5 wherein the element comprises a body of liquid within a closed container.

12. An inclinometer as claimed in any one of claims 1 to 5 wherein the element comprises a solid body movable along a track within predetermined limits.

13. An inclinometer as claimed in any preceding claim.

14. An inclinometer as claimed in any preceding claim wherein the inclinometer is mounted approximately at the eye level.

1 5. An inclinometer as claimed in any preceding claim arranged to indicate a safe attitude of the ladder when the ladder is inclined at substantially 150 to the vertical.

1 6. An inclinometer substantially as herein described with reference to any one Figure of the accompanying drawings.